A

AAMA: American Architectural Manufacturers Association

ACI: American Concrete Institute

ACIL: American Council of Independent Laboratories

AFA: American Fiberboard Association

AGC: Associated General Contractors of America

AHA: American Hardboard Association

AIA: American Institute of Architects

ANSI: American National Standards Institute.

APA: American Plywood Association.

APC: American Plastics Council.

APP: Please see Atactic polypropylene.

APC/SPFA: American Plastics Council/Spray Polyurethane Foam Alliance.

ARMA: Asphalt Roofing Manufacturers Association

ASA: American Subcontractors Association

ASC: Associated Specialty Contractors

ASHI: American Society of Home Inspectors

ASHRAE: American Society of Heating, Refrigerating & Air-Conditioning Engineers, Inc.

ASTM: American Society for Testing and Materials

AWPA: American Wood Preservatives Association

AWS: American Welding Society

Abrasion resistance: The capability to withstand erosion caused by moving surfaces is crucial for the longevity of materials. This resilience is essential for preserving structural integrity in urban infrastructure as well as common everyday items. Gaining insights into how materials respond to wear can boost their functional lifespan and enhance performance across a range of environments.

Absorption: Different materials exhibit varying capacities to soak up gases or liquids, including moisture. Accelerated weathering tests provide a means to replicate long-term weathering conditions in a compressed timespan, enabling scientists to assess material durability under exposure to sunlight, humidity, and fluctuating temperatures, thus yielding valuable performance insights without requiring extensive natural exposure.

Acid etch: In the context of waterproofing, a strong acid can erode the surface layer of concrete, unveiling the aggregate and improving bonding for subsequent treatments. This method necessitates meticulous adherence to safety protocols and desired effects to bolster both durability and performance across different settings.

Acrylic coating: A type of liquid coating that relies on an acrylic resin. Typically, it is a latex-based system that cures through air drying.

Acrylic resin: Polymers derived from acrylic or methacrylic monomers. Frequently utilized as a latex base in various coating systems.

Active: A material that will corrode when exposed to moisture or noble metals.

Active metal (anodic): A type of metal or substance reluctant to maintain its electrons when in the presence of a cathodic (noble) material. (See anodic.) This type of metal experiences corrosion in moisture-rich conditions when it is in contact with noble metals.

Adhere: The process in which one surface sticks to another, either at a molecular level or through other means.

Adhesion: A stable or firm attachment between materials.

Adhesive bond break: A material feature that allows movement between two units that would otherwise be bonded.

Aggregate: (1) Crushed stone, slag, or naturally-rounded gravel utilized in roofing surface layers; (2) Any form of granular substance.

Aged R-value: A value representing thermal resistance obtained through artificial conditioning techniques over a set timeframe.

Air Blown Asphalt: This type of asphalt is produced by introducing air into molten asphalt maintained at elevated temperatures, a process used to alter the asphalt’s properties.

Air leakage: The unintentional transfer of air from a confined space to another area.

Algae: A form of fungus found on rooftops, known to leave dark stains on roofing materials.

Alligatoring: A form of cracking that occurs in the surface layer of bitumen on a roofing system, resulting in a pattern that resembles alligator skin; the cracks might not traverse entirely through the material.

Aluminized steel: Steel sheets covered with a thin layer of aluminum for enhanced resistance to weathering.

Aluminum: A lightweight, malleable metal that does not corrode easily and is often used in roofing and flashing applications.

Anodic: When two different metals are interconnected within an electrolyte, they create a galvanic cell, where the more reactive metal becomes the anode, leading to oxidation and generating an electrical current that shields the cathode from corrosion.

Ambient Temperature: The temperature of the surrounding air.

Angled fasteners: Roofing nails and staples driven into base materials at angles that aren’t parallel to the surface.

Anticapillary hem: A special hem introduced in a metal panel seam to minimize the potential for water movement.

Application rate: The average amount (measured in mass, volume, or thickness) of the applied material per unit area.

Apron flashing: A term referring to flashing positioned at the junction between the top of a pitched roof and vertical structures like walls or chimneys.

Architectural Shingle: A type of shingle designed to provide a dimensional appearance, also known as Dimensional Shingle.

Area Divider: A flashing assembly that typically rises above the roof surface and is anchored to the deck. It is utilized to alleviate thermal strain in roof systems that do not require an expansion joint or to divide extensive roof areas.

Asbestos: An inorganic, fibrous mineral made of magnesium silicate that was previously used for its fireproofing qualities and, on occasion, as reinforcement in roofing materials.

Asphalt: A byproduct remaining after the evaporation or other processing of crude oil or petroleum. It can be refined to meet different roofing grade specifications.

Dead-Level Asphalt: Asphalt conforming to ASTM Specification D 312, Type I, designated for roof structures that do not exceed a slope of 2%.

Flat Asphalt: Asphalt conforming to ASTM Specification D 312, Type II, intended for roofing with a maximum slope of 4%.

Steep Asphalt: Asphalt that meets the requirements outlined in ASTM Specification D 312, Type III, for roofs with a slope not exceeding 25%.

Special Steep Asphalt: Asphalt adhering to ASTM Specification D 312, Type IV, applicable for roofs with slopes up to 50%.

Asphalt concrete primer: An asphalt-based primer used for prepping concrete and metal surfaces prior to applying an asphalt sealant.

Asphalt Emulsion: A blend of asphalt particles and an emulsifying agent such as bentonite clay and water.

Asphalt Felt: A material that has been saturated and/or coated with asphalt, typically in felt form. (See also Felt.)

Asphalt plastic cement: A type of asphalt-based sealant that meets ASTM D4586 Type I or II standards, employed to adhere roofing materials.

Asphalt Primer: Refer to Primer.

Asphalt Roof Cement: Officially known as Plastic Cement and Flashing Cement, this compound consists of solvent-based bitumen, mineral stabilizers, and various fibers (asbestos may be included). It is categorized by ASTM standard D 2822-91 (1997) or, for non-asbestos variants, ASTM standard D 4586-93.

Asphalt Shingles: Asphalt shingles, made from a blend of asphalt, fiberglass, and mineral granules, are popular for being budget-friendly and easy to install. Their durability, variety of styles, and aesthetic appeal make them a practical choice for roofing solutions in the construction industry.

Attic: The space found above a ceiling and directly beneath the roof deck on a steep-sloped roof.

Atactic Polypropylene: A classification of high molecular weight polymers formed via the polymerization of propylene.

B

BOCA: Building Officials and Code Administrators International, Inc.

BOMA: Building Owners & Managers Association International.

Back-nailing: Also termed “Blind-nailing,” this technique entails securing the rear portion of a roofing ply or steep roofing unit carefully covered by the next immediate ply to avoid exposure to the elements.

Back-Surfacing: A mineral coating on the underside of roofing materials like roll roofing to prevent them from sticking together during packaging.

Ballast: Materials such as aggregates or precast pavers that utilize their weight and gravitational force to hold single-ply roofing membranes securely in position.

Bar joist: Referred to as Steel joist.

Barrel vault: A building profile characterized by a rounded roof on the short axis, devoid of angle changes along the long axis.

Barrier board: A nonflammable board material with low thermal conductivity placed between two elements of a roof structure.

Base flashing: Strips or plies of roofing membrane material employed to seal a rooftop at horizontal-to-vertical intersections, such as where a roof meets a wall. Membrane base flashing conceals the edge of the field membrane. (See Flashing.)

Base ply: The foundational or first ply in a built-up roof membrane when additional plies are intended to be applied afterward.

Base sheet: A felt that has been impregnated, saturated, or coated, often serving as the initial ply in some low-slope roofing systems.

Batten: (1) A cover or cap; (2) In metal roofing, a closure that covers the joint between adjacent metal panels; (3) In wood roofing, a piece of wood utilized to elevate and/or secure primary roofing materials like tiles to the structural deck; (4) In single-ply membrane roofing, a slender plastic, wood, or metal bar used to hold in position or fasten the membrane and/or base flashing.

Batten seam: A metal panel profile attached to and formed around a beveled wood or metal batten.

Bentonite: A porous form of clay that expands up to six times its original volume when exposed to water.

Bermuda seam: A metal panel profile that features a step-down construction running perpendicular to the slope of the roof.

Bird bath: Trivial, incidental collections of residual water on a roofing membrane.

Bird Screen: Wire mesh positioned above openings to prevent birds from accessing buildings or roof cavities.

Bitumen: (1) An amorphous class of dark-colored, cementitious substances, either natural or manufactured, primarily composed of high molecular weight hydrocarbons that dissolve in carbon disulfide, found in asphalts, tars, pitches, and asphaltenes; (2) A general term signifying any substance mainly made up of bitumen, typically asphalt or coal tar.

Bitumen-stop: Refer to Envelope or Bleed-sheet.

Bituminous emulsion: A water suspension containing minuscule particles of bituminous material.

Blackberry: Also known as “Blueberry” or “Tar-boil,” this term describes a small bubble or blister that forms in the surface layer of an aggregate-surfaced built-up roof membrane.

Blanket insulation: Compressible fibrous insulation—like glass fiber—available primarily in roll form.

Bleed-sheet: A material sheet employed to keep bitumen from migrating.

Bleeder strip: See Rake-starter.

Blind-nailing: Using fasteners that will not be exposed in the final roofing assembly.

Blister: An air pocket trapped between impermeable layers of felt or membrane or between the membrane and the substrate, which may also contain water or solvent vapor.

Blistering: The formation of bubbles or pimples on roofing materials, generally related to moisture. In shingles, blisters may stem from moisture existing beneath or within the material.

Blocking: Wooden pieces embedded in roof structures providing reinforcement around openings, supporting curbs, or serving as nailers for fastening membranes or flashings.

Blow-offs: The phenomenon where shingles are dislodged from the roof deck due to high winds.

Blown Asphalt: See Air Blown Asphalt.

Blueberry: A small bubble in the surface layer of an aggregate-surfaced built-up roof. See also Tar Boil.

Bond: The forces that securely bind two components together.

Bonding Agent: A chemical used to form bonds between two layers.

Boot: A preformed piece of material designed to protect roof penetrations from moisture and dirt.

Brake: Equipment used to shape metal.

Bridging: When a membrane lacks support at a junction.

British Thermal Unit (BTU): The heat energy required to increase the temperature of one pound of water by one degree Fahrenheit—equivalent to a joule.

Brooming: The process of using a broom, squeegee, or other tool to embed a ply of roofing material into hot bitumen or adhesive, ensuring a complete seal and eliminating voids.

Buckle: A long, tented deformation occurring in the roof membrane, typically over insulation and deck seams.

Buckling: A condition where shingles or their underlayments exhibit ripples or wrinkles.

Built-Up Roof Membrane: A roofing assembly comprising layers of bitumen that function as the waterproofing substance, with reinforcement fabrics integrated within each layer. Generally topped with a surfacing applied, which may consist of asphalt, aggregate, emulsion, or a granule-surfaced cap sheet.

Bulb-Tee: A steel component used in constructing pre-stressed, poured gypsum decks, encased by the poured gypsum for support.

Bundle: An individual package of shingles or shakes.

BUR: An acronym for Built-Up Roof. See Built-Up Roof.

Butadiene: A colorless, highly flammable hydrocarbon (C4H6) derived from petroleum, utilized in synthetic rubber production.

Butt Joint: The meeting point where two individual, adjacent materials abut each other.

Butyl: A rubber-like hydrocarbon radical (C4H9) formed from the copolymerization of isobutylene and isoprene, predominantly used in adhesives and sealants.

Butyl Rubber: A synthetic elastomer derived from butyl.

Butyl Tape: A sealant tape commonly employed in various sealing applications, like joining sheet metal segments.

C

CABO: Council of American Building Officials.

CCF: An acronym representing 100 cubic feet.

Calender: (1) To press between rollers or plates to smooth or glaze; (2) Equipment used for calendering.

Calendering: A specific method often used in manufacturing certain membranes, including PVC.

Camber: A slight arching or curvature observed in objects such as beams, roadways, or roof decks.

Canopy: a projecting structure, often a roof, that typically hangs over entrances or doors.

Cant: a beveled foam application at horizontal and vertical roofing joints in SPF-based systems to enhance durability and facilitate water drainage.

Cant strip: a sloped strip positioned beneath flashings to adjust the angle where roofing or waterproofing membranes meet vertical structures.

Cap flashing: (1) typically made of metal, this element protects the upper edges of membrane base flashing or wall flashing; (2) a protective covering for the tops of various building features, such as parapets or columns.

Cap sheet: a granule-top sheet serving as the upper layer in built-up or modified bitumen roof membranes and flashings.

Capacitance meter: a tool that detects moisture or damp materials within roof systems by assessing the change in potential difference between two conductive elements separated by a non-conductive medium.

Capillary action: (1) the process where the surface of a liquid interacts with a solid, causing elevation or depression based on the molecular attraction of the liquid and solid; (2) the absorption of liquid into the space between two neighboring surfaces.

Catalyst: a substance that triggers a chemical reaction or accelerates the rate of a reaction when mixed with another chemical.

Cathodic: a metal or substance that effectively attracts electrons from another electrochemical material when an electrolyte is present (refer to Galvanic Series).

Caulk: an elastic compound composed of vehicle and pigment for sealing joints or gaps at ambient temperatures, maintaining its pliability post-application.

Caulking: (1) the act of sealing a joint or connection; (2) the process of filling joints, seams, or gaps between adjacent surfaces to create a weather-tight seal with a sealant.

Cavitation: the development of a partial vacuum or void in a liquid.

Cavity wall: a masonry exterior wall featuring an outer and inner withe separated by a continuous air gap and connected by wire or sheet-metal ties.

C-channel: a structural support member shaped in a channel form.

Cellular glass insulation: a rigid insulation board composed of recycled glass and hydrogen sulfide gas, characterized by a closed-cell structure.

Cellulose: a complex carbohydrate, (C6H10O5)n, made of glucose units that forms the primary component of plant cell walls, utilized in producing organic roofing materials.

Cementitious waterproofing: heavy cement-based mixtures combined with various additives, supplied in dry form, which are then mixed with water and liquid bonding agents to reach a workable, concrete-like consistency.

Centipoise: a measure of absolute viscosity, where one centipoise represents the viscosity of water, with lower values indicating less viscous materials.

Centistoke: a viscosity unit representing the ratio of a liquid’s absolute viscosity to its density.

CERL: Construction Engineering Research Laboratory.

Certified GAF Roofing Contractor: A “certified GAF roofer” is a roofing professional endorsed by GAF, indicating they meet specific quality standards through training and assessments. Hiring one ensures skilled installation of GAF systems, maintaining roofing integrity and enhancing investment value while providing homeowners peace of mind.

Chalk: a powdery residue left on a material’s surface.

Chalk Line: (1) a string wound on a reel, encased in a container holding chalk; (2) a line marked by tautly pulling a chalk-coated string and snapping it.

Channel Flashing: a flashing type that has an integrated channel for drainage; typically used where roof planes converge with vertical surfaces.

Chemical Resistance: the capability of a material to maintain its properties upon exposure to specific chemicals.

Chlorinated Polyethylene (CPE): a flexible material known for its high tear resistance, effective chemical resistance, and UV stability. Due to its high chlorine content (around 30%), it is challenging to ignite but releases hydrogen chloride when burned. It exhibits extremely high gas permeability, with good mineral chemical resistance but improved resistance to hydrocarbons as chlorine content increases. This material is largely utilized as an impact modifier for PVC and, to a smaller extent, for LDPE and HDPE films.

Chlorosulfonated Polyethylene: a synthetic, rubber-like thermoset polymer based on high molecular weight polyethylene and suphonyl chloride, often formulated to yield a self-vulcanizing membrane. Commonly known as Hypalon™, it was originally developed by DuPont in 1951.

Chopped Glass and Emulsion (CG&E): a roofing coating made from asphalt or clay emulsion combined with short glass fibers. These fibers, initially in rope form, are mechanically chopped and mixed with the emulsion just before application to ensure thorough integration by the time it reaches the roof. The standard formulation consists of 9 gallons of emulsion and 3 pounds of glass fiber for every 100 square feet (or 36.5 liters of emulsion and 1.5 kg of glass for each 10 square meters), typically topped with a fibered aluminum coating at a rate of 1.5 gallons per 100 square feet (6 liters per 10 square meters).

Cladding: material used to cover the outer wall surface of a structure.

Cleat: a continuous metal strip that secures two or more components of a metal roof together, frequently used alongside coping or gravel stops on tall buildings.

Clerestory (Clearstory): a space that rises above a neighboring roof section in a building.

Clip: a minor cleat, as defined by Cleat.

Clipped Gable: a gable that’s truncated at the ridge, forming a compact hip shape.

Closed-Cut Valley: a technique for valley installation where shingles from one side extend over the valley and those from the opposite side are laid over them, trimmed back approximately 2 inches from the middle of the valley.

Closure Strip: a component utilized to seal gaps created when joining metal panels or sheets and flashings.

Coal Tar Bitumen: a specific trade name for Type III coal tar utilized in flat or low-slope built-up roofing systems, not suitable for roofs with slopes exceeding _” in 12” (2%).

Coal Tar Pitch: a form of coal tar intended for dead-level or low-slope built-up roofs, similarly restricted from use in slopes exceeding _” in 12” (2%).

Coal Tar Felt: a roofing layer soaked in refined coal tar.

Coal Tar Roof Cement: a trowel-applied mixture comprising processed coal tar, solvents, mineral fillers, and/or fibers.

Coarse Orange Peel Surface Texture: a textured surface marked by nodules and valleys of similar size and shape, generally deemed suitable for applying protective coatings.

Coated Base Sheet: an asphalt-saturated base sheet membrane layered with a tougher, more viscous asphalt to enhance moisture impermeability.

Coated Felt: an asphalt-saturated ply sheet additionally coated on both sides with a denser, more viscous asphalt.

Coating: a protective or decorative layer applied over a surface through spraying, rolling, or brushing.

Cohesion: the intrinsic force that holds together the elements or particles within a body or material.

Coil Coating: the process of applying a finish to a coil of metal or another substance.

Cold Forming: the technique of shaping metal into desired designs at room temperature.

Cold Process Built-Up Roof: a roofing system comprising multiple layers of felts bonded with adhesives that do not require heating, coming directly out of a can or barrel.

Collector Head: A component designed to channel water from a through-wall scupper to a downspout, also referred to as a Conductor Head.

Column: A vertical structural element placed on a footing or foundation that supports horizontal components of a building above ground.

Combing Ridge: A term referring to the installation of finishing slate at the apex of a roof, where slates on one side extend beyond to meet at the top.

Combustible: Capable of catching fire and burning.

Composition Shingle: A type of shingle utilized in steep-slope roofing, typically made from weathering-grade asphalt, a fiberglass reinforcing mat, an adhesive strip, and mineral granules.

Compounded Thermoplastics: Roofing membranes created by blending thermoplastic resins with plasticizers, modifiers, stabilizers, flame retardants, UV blockers, fungicides, and other proprietary materials, combined with unique organic polymers. Examples of membranes in this category include CPA, EIP, NBP, and TPA.

Concealed-Nail Method: A technique for installing asphalt roll roofing where all nails or fasteners are driven into the base roofing and concealed by an overlapping layer.

Condensate: The liquid formed from condensation.

Condensation: The transformation of water vapor into liquid when warm air comes into contact with a colder surface. (Refer also to Dew Point.)

Conduction: The process of transmitting something through a medium, particularly the transfer of electric charge or heat through a conducting medium without noticeable movement of the medium itself.

Conductor Head: A device that directs water from a through-wall scupper to a downspout, also known as a Collector Head.

Construction Joint: A constructed joint where two successive pours of concrete meet.

Contact Cements: Adhesives used to bond roofing components together.

Coping: A protective material placed on top of a wall to shield it from weather conditions, which can be made from metal, masonry, or stone.

Copper: A reddish-brown metal known for its excellent heat and electricity conductivity, frequently utilized as a primary roofing material and in flashing. Over time, copper will develop a greenish patina when exposed to the elements.

Cornice: A horizontal overhanging feature that crowns the top of a building wall.

Corrosion: The deterioration of roofing metals due to rust, decay, or aging.

Counter Batten: Vertically installed wooden strips on sloped roofs, upon which horizontal battens are fastened.

Counterflashing: Metal sheeting affixed to walls, curbs, or other surfaces to shield the upper edge of base flashings from weather exposure.

Course: (1) The term denoting each row of roofing material constituting the roofing or flashing system; (2) One of multiple layers of material applied to a surface. For instance, a three-course flashing involves a layer of mesh or reinforcing material sandwiched between two layers of roofing cement.

Cove: In roofing, a substantial bead of sealant applied at the junction of vertical and horizontal planes to eliminate the sharp angle. See also Fillet.

Cover Plate: A metal strip often placed over the joint between formed metal pieces.

Coverage: The total area that a material covers.

CPA: Copolymer Alloy.

CPE: Chlorinated Polyethylene.

Crack: A separation or fracture occurring in a material. (Refer also to Split.)

Cream Time: The duration in seconds at a specific temperature during which the A and B (isocyanate and resin) components of SPF will start to expand after being combined.

Creep: The movement of the roof membrane that leads to deformation of the roofing system.

Cricket: A roofing element designed to divert water away from curbs, platforms, chimneys, walls, or other roof projections. Refer to Saddle for more details.

Cross Ventilation: The movement of air through a roof cavity between vents.

CRREL: Cold Regions Research and Engineering Laboratory.

Crow’s Nest: See Cupola.

CSI: Construction Specifications Institute.

CSM: ASTM designation for Chlorosulfonated polyethylene. (Refer to CSPE.)

CSPE: Chlorosulfonated polyethylene.

Cupola: A small roofed structure placed atop the ridge of a main roofing area, also known as a Crow’s Nest.

Cupping: A condition where shingles are improperly installed over an existing roof or are over-exposed, causing them to curl or form a cup shape.

Curb: (1) A raised element designed to support skylights, HVAC units, exhaust fans, hatches, or other mechanical equipment above the roof surface, with a minimum height of eight inches (8”); (2) A low raised perimeter around the roof.

Cure: The process by which a material forms permanent molecular connections through exposure to chemicals, heat, pressure, and/or weathering.

Cure Time: The duration needed for the curing process to take effect.

Curing Agent: An additive that modifies the chemical interactions between components, thus altering the rate of curing.

Curing Compound: A liquid applied to newly placed concrete to mitigate water loss during curing.

Cutback: Bitumen that has been diluted with solvents and is utilized in cold-process roofing adhesives, roof cements, and coatings.

Cutoff: A permanent detail designed to prevent lateral water movement within an insulation system, allowing for isolation of roofing sections. (Note: A cutoff differs from a tie-in, which can be temporary or permanent; see Tie-In.)

Cutout: The open sections of a strip shingle between the tabs, sometimes called a keyway.

D

Dampproofing: The process of treating a surface or structure to impede water penetration in the absence of hydrostatic pressure.

Dead level: Completely horizontal with no slope. (Refer to Slope.)

Dead-level asphalt: See Asphalt.

Dead loads: The inherent weight of a structure, encompassing the weight of any fixtures or equipment permanently attached.

Deck: The primary structural component of a roof, which must safely support the designated dead and live loads while providing a substrate for roofing or waterproofing systems. Decks can be either non-combustible (e.g., corrugated metal, concrete, or gypsum) or combustible (e.g., wood plank or plywood).

Deflection (bowing, sagging): (1) The deformation that occurs in a structural member due to the impact of loads; (2) Any shift in a body from its original position or from a defined direction or plane due to applied forces.

Degradation: A detrimental alteration in the chemical composition, physical properties, or appearance of a material due to natural or artificial influences (e.g., exposure to radiation, moisture, heat, freezing, wind, ozone, oxygen, etc.).

Degree days: A unit for estimating the fuel consumption of a building, calculated based on the degree difference from a predefined temperature over a 24-hour period; in the U.S.A., the base temperature is typically recognized as 65° F (18.3° C).

Delamination: The separation of laminated layers within a component or system.

Design loads: The cumulative load that a structural system is designed to endure under the most extreme combination of forces and loads.

Design Your Roof Software: Roof design applications enable users to create detailed roofing plans with 3D visuals, material choices, and customizable templates. These tools enhance efficiency and accuracy, improve collaboration among stakeholders, and transform the planning and execution of roofing projects.

Dew-point temperature: The temperature at which air reaches saturation with water vapor, effectively achieving a relative humidity of 100%.

Diaphragm: A structural element, such as a floor slab, metal wall panel, or roof panel, possessing significant in-plane shear stiffness and sufficient strength to transfer horizontal forces to supporting systems.

Diffusion: The process of water vapor movement from areas of high concentration (elevated water vapor pressure) to regions of lower concentration.

Dimensional shingle: A shingle type that features texture, overlay, or lamination, crafted to create a three-dimensional visual effect. (Refer also to Laminated shingle and Architectural shingle.)

Dimensional stability: The ability of a material to retain its original dimensions despite variations in temperature and humidity.

DOE: U.S. Department of Energy.

Dome: A roof characterized by a partially spherical shape.

Dormer: A structure protruding from a sloping roof, typically housing a window or ventilating louver.

Double coverage: The application of asphalt, slate, or wood roofing such that the overlapping section is at least 2 inches (50 mm) wider than the visible portion, resulting in two layers of roofing material atop the deck.

Double Graveling: The process of applying one layer of gravel within a flood coat of hot bitumen, removing excess gravel, and then adding a second layer of gravel in another flood coat of hot bitumen.

Double lock standing seam: In metal roofing, a standing seam that utilizes a double overlapping interlock between two metal panels. (Refer to Standing seam.)

Double pour: The application of two layers or flood coats of bitumen and aggregate onto a built-up roof.

Downspout: A vertical pipe or conduit responsible for channeling runoff water from a scupper, conductor head, or gutter down to a lower roof level or the ground/stormwater drainage system.

Drag load: The external force (for example, from accumulated ice and snow) acting on a steep-slope roof component, pushing it down the slope.

Drain: A device or outlet utilized for collecting and directing runoff water from a roofing area.

Drip edge: A flashing or protruding metal component designed to manage water dripping and protect underlying building elements.

Dry: Largely free from liquid, particularly water; (2) to remove water or moisture content from a surface.

Dry bulb temperature: the air temperature as indicated by a conventional thermometer.

Dry film thickness: the thickness of a cured coating or mastic, measured in mils. For context, refer to Wet film thickness.

Dry-In: (1) The installation process of underlayment in steep-slope roofing; (2) The action of making a low-slope roof watertight, which does not necessarily require all the specified layers to be installed.

Dry Rot: A type of wood decay caused by specific fungi. This condition may arise from condensation accumulation, unresolved roof leaks, or other issues. The spread of dry rot is often unpredictable and can damage any timber in contact with the affected area.

Drying time: the duration needed for volatile substances to dissipate, ensuring that the material is no longer negatively impacted by weather conditions such as dew, rain, or frost.

Dual level drain: a waterproofing feature designed with drainage capabilities at both the upper surface and waterproof membrane levels, facilitating the collection and redirection of runoff from a horizontal slab.

Dynamic load: any non-static load, such as wind force or moving live loads.

E

Eave: the lower edge of a sloped roof, where the roof extends beyond the wall.

Eave height: the vertical distance from the finished grade to the eave.

Eave-trough: see Gutter.

ECH: polyepichlorohydrin, commonly known as epichlorohydrin. (Refer to Epichlorohydrin for more details.)

Edge stripping: membrane flashing strips tailored to specific widths utilized for sealing perimeter edge metal and incorporating roofing membranes, often involving felt strips narrower than the standard roll width to cover the joint between metal perimeter flashing and built-up roofing.

Edge venting: the method of creating regularly spaced or continuously shielded openings along a roof’s edge, integrated into a ventilation system designed to expel heat and moisture vapor.

Efflorescence: a white, encrusted deposit of soluble salts found on the surfaces of stone, brick, plaster, or mortar, typically a result of free alkalies leached from mortar or nearby concrete as moisture permeates it.

EIP: ethylene interpolymer.

Elasticity: a characteristic of a material that allows it to revert to its original form following deformation (such as stretching, compression, or torsion).

Elastomer: a macromolecular substance that quickly returns to its nearly original dimensions and shape after significant deformation caused by a light stress and the subsequent removal of that stress.

Elastomeric: the qualities of a material enabling it to return to its original shape after being stretched.

Elastomeric coating: a versatile coating capable of being stretched to at least double its initial length (100 percent elongation) and regaining its original dimensions.

Elongation: the proportion of extension of a material relative to its length before stretching.

Embedment: In roofing, the uniform pressing of one material into another, such as aggregate into bitumen or roofing felt into bitumen.

Emergency Roof Repair: This involves urgent repairs due to sudden damage, like leaks from storms or falling branches, necessitating quick intervention by a roofing contractor to prevent further interior damage, typically requiring a 24/7 service to temporarily cover leaks until full repairs can be completed.

Emulsion: fine particles suspended within a liquid medium. Refer to Asphalt Emulsion and Bituminous Emulsion for more insights.

End Lap: the segment of one material’s component extending past the end of an adjacent piece.

Envelope: a continuous sealing mechanism that prevents bitumen from leaking down into or off a structure. This involves extending the base sheet or other non-porous felt layers beyond the edge of the primary layers, which is then folded back and adhered.

EPDM: Ethylene Propylene Diene Monomer.

Epichlorohydrin (ECH): a synthetic rubber that resembles EPDM but offers greater resistance to animal fats and oils.

Epoxy: a form of synthetic, thermosetting resin that produces robust, durable, and chemically resistant coatings and adhesives.

Equipment Screen: a non-structural enclosure or partition surrounding rooftop apparatus like HVAC units, designed to enhance the aesthetic appeal of the structure.

Equiviscous Temperature (EVT): the specific temperature at which a bitumen achieves the appropriate viscosity for built-up roofing. Typically, a variance of twenty-five degrees Fahrenheit (25° F) is allowed above and below the recommended EVT. This measurement is typically taken in application equipment immediately before use with a standard thermometer or shortly after with a laser thermometer.

Ethylene Propylene Diene Monomer (EPDM): a thermoplastic rubber characterized by high tear resistance, which can be cross-linked using both peroxides and sulfur.

EVT: Equiviscous Temperature.

Exhaust Vent: a mechanism installed on or near the higher portions of a roof, such as the ridge, used to expel air from the roof cavity.

Exotherm: the heat produced by a chemical reaction.

Expansion cleat: a fastening device that allows for thermal movement of metal roof panels.

Expansion joint: a structural separation allowing autonomous movement between two components, preventing damage to the roofing or waterproofing system.

Exposed-nail method: a technique of applying asphalt roll roofing where all nails are inserted into the adhered, overlapping roofing layer, leaving the nails exposed to the elements.

Exposure: (1) the horizontal dimension of a roofing element or component not overlapped by an adjacent element in the roof covering. For example, the exposure of any ply in a built-up roof membrane can be calculated by subtracting 2 inches (51 mm) from the felt width and then dividing by the number of shingled plies; thus, the exposure of a 36-inch (914 mm) wide felt in a four-ply shingled membrane is roughly 8.5 inches (216 mm). (See Figure 8); (2) the portion of a sidewall or roofing material that isn’t covered or overlapped by the upslope course of the component. Typically, the exposure for a standard-sized three-tab shingle is 5 inches (127 mm), though this can vary by manufacturer standards.

Extrusion: a technique where heated or unheated material is forced through a shaping orifice (die) into a continuous form, such as film, sheet, rod, or tubing.

Eyebrow: a small dormer characterized by a roofline that arches over the upright face, forming a reverse curve at either end, or a minor shed roof extending from the gable.

F

FHA: The Federal Housing Authority. This organization establishes construction standards across the U.S.

Fabric: a woven material made of organic or inorganic fibers or threads utilized for reinforcement in certain membranes and flashings.

Factory Mutual Research (FMR): commonly referred to as “FM,” a research and testing organization that evaluates roofing components and assemblies for their fire resistance, traffic capability, impact (hail) resistance, durability, and wind-uplift resistance on behalf of four major insurance companies in the United States.

Factory seam: a joint fabricated by the manufacturer during the assembly of material sections into larger sheets or panels.

Fading: the process of lightening initial colors.

Fallback: a decrease in the softening point of bitumen, sometimes due to overheating or refluxing in a relatively confined container. (Refer to Softening Point Drift for further information.)

Fascia: (1) in steep-slope roofing, a board affixed to the ends of roof rafters, which may also support a gutter; (2) in low-slope roofing, the vertical or steeply sloped trim located at the building’s perimeter, typically serving as a border for the low-slope roofing system.

Fastener: any various mechanical securing devices and assemblies, including nails, staples, screws, cleats, clips, and bolts, used to attach diverse components of a roofing assembly.

Feathering strips: tapered wooden strips placed at the butt ends of aged wood shingles to achieve a smoother surface when re-roofing over existing shingles. These are referred to in some regions as “horse feathers” or leveling strips.

Felt: a pliable sheet produced by interlocking fibers, bound together by a binder or through a combination of moisture, heat, and mechanical work. Felt is primarily made from wood pulp and vegetable fibers (organic felts), asbestos fibers (asbestos felts), glass fibers (glass fiber felts or ply sheets), or polyester fibers.

Felt machine (Felt Layer): a mechanical apparatus used for the simultaneous application of bitumen and roofing felt or ply sheet.

Ferrule: a metallic sleeve inserted into a gutter’s top. A spike or screw is driven through the gutter’s face and ferrule into the fascia board, securing the gutter in place and acting as a spacer to retain its structure.

Fiberglass Insulation: insulation made from glass fibers, utilized in wall and roof applications. This can come in rigid board format or as blanket insulation.

Fiberglass mat: fibers compressed into durable, resilient mats used in roofing applications.

Field of the Roof: references the central area of a roof, away from its edges.

Field Seam: a non-manufactured joint created by joining overlapping seams using adhesives, heat welding, or alternative methods.

Filler: a non-reactive material added to roofing products to modify their physical properties.

Fillet: a sealing material applied at horizontal and vertical junctions to smooth out 90° angles.

Film: a membrane or sheet material with a thickness of 10 mils or less.

Film Thickness: the measurement of a membrane or coating’s thickness expressed in mils (thousandths of an inch). See also Wet Film Thickness and Dry Film Thickness.

Fin: a pointed projection found in roof decking that poses the risk of damaging roofing components.

Fine Mineral-Surfacing: a very fine mineral layer applied to roofing materials to prevent surface adhesion. At least 50% of this material must pass through a sieve with holes measuring 1/35” in size (#35 sieve).

Fishmouth: an opening along the exposed edge of an installed felt ply, resulting from misalignment during installation. Repair involves cutting along the length of the opening and overlapping two layers of felt over the fishmouth to ensure at least one foot of coverage all around.

Flaking: occurs when a coating loses its adhesion.

Flame Retardant: a material utilized to reduce a substance’s likelihood of igniting or combusting.

Flame Spread: a measure evaluating the relative combustibility of a material, rated against asbestos cement board (flame spread = 0) and red oak flooring (flame spread = 100).

Flammability: the propensity of a substance to ignite or catch fire.

Flange: a projecting edge of a roof element, such as flashings, frames for skylights, pre-manufactured curbs, etc. It generally refers to the part that rests on the roof.

Flash: v. To apply flashing components.

Flash Point: the lowest temperature at which a liquid will ignite when exposed to air.

Flashing: elements utilized to seal the roofing system where interruptions or terminations occur, such as with pipes, curbs, and walls. When correctly installed, flashing effectively prevents moisture intrusion into the roof system or building.

Flashing Cement: a trowelable blend of solvent-based bitumen mixed with mineral stabilizers.

Flashing: elements utilized to seal the roofing system where interruptions or terminations occur, such as with pipes, curbs, and walls. When correctly installed, flashing effectively prevents moisture intrusion into the roof system or building.

Flashing Cement: a trowelable blend of solvent-based bitumen mixed with mineral stabilizers. Flashing cement that may contain asbestos stabilizers is categorized by ASTM standard D 2822-91 (1997) or, for non-asbestos varieties, ASTM standard D 4586-93. Flashing Cement refers to Asphalt Roof Cement applicable for vertical surfaces, characterized by a high softening point, low ductility, and compliance with ASTM Specification D 312, Types II or III; or Specification D 449, Type III. See also Asphalt Roof Cement and Plastic Cement.

Flashing Collar: a flashing component designed to seal soil pipe vents, hot stacks, or other penetrations in the roof.

Flat Lock: a method of interlocking two separate metal panels by folding one panel over itself and then tucking the other underneath, securing the panels together.

Flat Roof Installation: Flat roof installation involves applying a waterproof barrier, usually rubber or PVC, over a nearly horizontal surface. Key steps include removing old materials, preparing the deck, installing insulation, and sealing seams. Effective drainage is crucial to prevent water pooling, necessitating careful planning and material selection based on climate and design.

Fleece: mats or felts composed of fibers often employed as backing for membranes.

Flood (pour) coat: the outer layer of bitumen into which surfacing aggregate is embedded on an aggregate-surfaced built-up roof.

Flood test: a process wherein a controlled volume of water is temporarily held over a horizontal area to evaluate the effectiveness of the waterproofing system.

Fluid-applied elastomer: a liquid elastomeric substance that cures post-application to establish a seamless waterproofing membrane.

Fly-in: an application method for roll materials where the dry sheet is positioned into the bitumen or adhesive spread on the roof surface.

FM: see Factory Mutual Research (FMR).

Foam Roof Installation: Spray polyurethane foam is a versatile roofing solution that expands upon application, sealing cracks and gaps for a water-resistant barrier. It enhances insulation and durability against water intrusion, ensuring long-term performance and energy efficiency while minimizing potential leaks with seamless coverage. Proper application is crucial for optimal benefits.

Foam stop: the finishing treatment at the roof edge where SPF is concluded.

Force: a strength or energy applied or exerted; a catalyst for motion or change.

FPL: Forest Products Laboratory.

Framed Opening: a framed structural gap within a roof designed for the installation of large items like HVAC units, skylights, or ventilators.

Froth pack: a term referring to small, disposable aerosol cans that contain SPF components, available in two-component varieties for minor repairs on sprayed polyurethane foam roofs.

G

G-90: a designation for galvanized metal sheets, indicating a coating of 0.90 ounces (26 g) of zinc per square foot, measured on both sides.

Gable: the vertical triangular portion at the end of a building featuring a double-sloping roof, extending from the eaves to the roof ridge.

Gable roof: a single-ridge roof that concludes at one or both gable ends.

Gable-On-Hip Roof: a roofing arrangement featuring hips originating from the eave corners, culminating in a gable roof.

GAF: GAF, or General Aniline & Film, is a leading manufacturer of roofing and waterproofing materials in the U.S. One in four roofs are built with materials from GAF.

Galvalume: a brand name for a metal alloy coating comprised of aluminum, zinc, and silicone.

Galvanic action: an electrochemical phenomenon that produces electrical current between two metals with differing electrode potentials.

Galvanic series: a compilation of metals and alloys ordered by their relative electrolytic potentials in a specific environment.

Galvanize: to coat iron or steel with zinc.

Galvanized steel: steel that has been coated with zinc to prevent corrosion.

Gambrel: a roofing style featuring two distinct slopes on each side, where the upper portion has a shallower incline compared to the lower areas.

Gauge: a measurement for metal thickness.

Geocomposite: a prefabricated drainage solution used to alleviate hydrostatic pressure against waterproofing and facilitate drainage.

Geodesic Dome: a structure that employs a configuration of self-supporting triangles to offer optimal structural benefits while minimizing material usage. A “geodesic” line is defined as the shortest path between any two points on a sphere, with the first modern examples recorded from Walter Bauersfeld during the early 20th century.

Geotextile: a densely woven material designed to prevent the passage of fine soil particles and other contaminants while allowing water to flow freely; utilized to protect drainage systems from becoming clogged.

Girt: A horizontal support beam designed to hold wall cladding in position between columns.

Glass fiber insulation: Insulation material available in blanket or rigid board form, made from interconnected glass fibers with a binding agent. It can be faced or unfaced and is used to insulate roofs and walls.

Glass felt: A composite of glass fibers bonded with resin into sheets, which can be treated with asphalt for producing bituminous waterproofing products, including roofing membranes and shingles.

Glass mat: A lightweight mat created from glass fibers, available with or without a binding agent.

Glaze coat: (1) The uppermost layer of asphalt in a smoothly surfaced built-up roofing membrane; (2) A thin protective layer of bitumen applied to the lower layers or top layer of a built-up roof membrane if additional felts or the flood coat and aggregate surfacing cannot be immediately applied. (see also Flood coat.)

Gloss: The visual quality of sheen, shine, or luster seen on a dried coating.

Grain: A unit of measurement in the imperial system; 7,000 grains is equivalent to 1 pound; typically used to quantify moisture weight in the atmosphere.

Granule: Also known as mineral or ceramic granule, these are opaque, naturally or synthetically colored aggregates frequently employed to surface cap sheets, shingles, and various other granule-finished roofing materials.

Gravel: A coarse aggregate created from the natural weathering of rock.

Gravel stop: A flanged device, often metallic, designed to prevent the loss of loose aggregate from the roof and to provide a consistent finished edge for roofing.

Groundwater level: The depth below the surface at a specific location, where the subsoil and rock are saturated with water.

Grout: A blend of cement, sand, and water utilized to fill voids and cracks in masonry.

Gusset: A broad, flat piece of metal, wider than the valley, situated at the base of the valley in a steep-slope roofing system to mitigate accumulation from debris or ice dams.

Gutter: A channeling component installed along the downslope edge of a roof that directs runoff water to drainage leaders or downspouts.

Gypsum board panels: Cement-based board materials containing a noncombustible gypsum core, typically used as a thermal barrier or cover board within roofing assemblies.

H

HVAC: Abbreviation for Heating, Ventilation, and Air Conditioning.

Half Gable Roof: Refer to Shed Roof.

Hand-sealing: A technique employed to ensure the sealing of shingles on steep slopes, in high-wind environments, or when installing under cold conditions.

Hand-tabbing: A method of applying asphalt-based adhesive in specific spots to secure shingles and improve resistance against wind.

Hatch: A structural unit facilitating access to a roof from within a building.

Headlap: The overlap distance measured from the highest ply or course to where it overlaps the lowest ply or course.

Heat flow: The rate at which heat is transferred to or from a system over a specified period.

Heat seaming: The technique of joining thermoplastic films, membranes, or sheets through heat application followed by pressure to merge the materials.

Heat transfer: The process of thermal energy moving from a higher temperature area to one of lower temperature, occurring via conduction, convection, or radiation.

Heat welding: A technique for melting and joining overlapping edges of different sections of polymer-modified bitumen, thermoplastics, or uncured thermoset roofing membranes by applying heat and pressure. (see Heat seaming.)

Hem: The folded edge created by turning metal back upon itself.

High nailing: The practice of fastening shingles above the manufacturer’s specified nail placement.

Hip: The sloped external angle created by the convergence of two inclined roof planes.

Hip legs: The down-sloping edges on hip roofs.

Hip roof: A roofing structure with inclined planes merging to form one or more hips.

Hoist: A mechanical device used for lifting.

Holiday: An area where a liquid-applied material is absent or lacks coverage.

Homeowners Roof Insurance: Homeowners’ roof coverage is vital for financial support in case of damage from insured hazards. This insurance protects a key part of your home, providing peace of mind and ensuring your investment is safe from unexpected events.

Honeycomb: Cavities found in concrete caused by mortar inadequately filling spaces among coarse aggregate particles.

Hot or Hot Stuff: A colloquial term used by roofing workers to refer to hot bitumen.

How to Find a Roof Leak: Identifying moisture entry points on your roof is vital for a safe home. Look for interior water stains, damp attic insulation, or wet roof patches, which indicate roofing issues. Addressing these signs promptly can prevent further damage and ensure your roof continues to protect your home effectively.

Hue: The subjective characteristic of color perception, such as red, yellow, green, blue, or purple; colors like white, black, or gray do not have a hue.

Humidity: The atmospheric condition regarding the presence of water vapor; see relative humidity. HVAC refers to heating, ventilating, and air conditioning systems.

Hybrid roof covering: The integration of multiple distinct roof membranes, such as three-ply smooth BUR combined with a modified bitumen cap.

Hydration: The chemical reaction where a substance, like Portland cement, combines with water, releasing heat and creating a crystalline structure as it sets and hardens.

Hydrocarbon: An organic chemical compound mainly consisting of carbon and hydrogen.

Hydrostatic pressure: The pressure exerted on a surface by a column of water at a specified height.

Hydrostatic pressure relief system: A network of perimeter and/or subsurface drains designed to manage hydrostatic pressure around below-grade structures.

Hygroscopic: Having the ability to attract, absorb, and retain moisture from the atmosphere.

Hypalon™: Registered trademark of E.I. du Pont de Nemours & Co. for chlorosulfonated polyethylene (CSPE). (see Chlorosulfonated polyethylene.)

I

ICBO: The International Conference of Building Officials.

IRWC: The Institute of Roofing and Waterproofing Consultants.

Ice dam: A build-up of ice formed at the transition between warm and cold roof surfaces, often created by the refreezing of meltwater at roof overhangs, which can lead to water backing up beneath roofing materials.

Ice dam protection membrane: A continuous membrane installed under steep-slope roofing systems in areas vulnerable to ice dam formation, which prevents water that penetrates the roof covering from entering the structure and seals the fasteners passing through it.

Ignition temperature: The minimum temperature at which a material will ignite spontaneously under particular conditions.

IKO Roofing Products: IKO, founded in Canada in 1951, specializes in asphalt shingles and is a significant player in the international roofing market. The company focuses on quality, sustainability, and innovation through a vertically integrated manufacturing system, maintaining a strong reputation with its notable “Cambridge” architectural shingles.

Impact resistance: The ability to withstand fracture when subjected to sudden force.

Impregnate: In the manufacturing of roofing materials, to entirely encase the fibers in a felt or mat with bitumen, partially or fully filling the spaces between fibers without forming a continuous exterior layer of bitumen.

Infrared thermography: The method of visualizing differences in apparent temperatures across an object’s surface by measuring variations in infrared radiation.

Infrared Thermography: The application of an infrared camera to identify moisture within roofing insulation.

Inorganic: Composed of materials that are not hydrocarbons or derivatives thereof, or matter that is not of plant or animal origin.

Insect screen: A mesh barrier utilized to prevent insects from entering buildings through vents, louvers, or other openings.

In-service R-value: The thermal resistance value determined under actual installed conditions and assessed over the expected lifespan of the material.

Insulation: a diverse range of materials intended to minimize heat transfer, whether entering or leaving a building. (refer to Thermal insulation for further details).

Insurance Claim Process: Here is a summary of how the insurance claim process works after calling your homeowners insurance. 1. Claim specialist will evaluate the extent of the damage. 2. Review your insurance policy. 3. Take detailed notes and photos of the damage. 4. Inform your insurance provider about the situation. 5. Reach out to a roofing contractor. 6. Submit your insurance claim.

Intake ventilation: the process by which fresh air is introduced into a passive ventilation system via vents generally situated in the soffit or eave areas of a roof.

Interlayment: a felt, metal, or membrane-like material placed between layers of steep-slope roofing to enhance its ability to shed water and withstand weather during windy, rainy conditions. Commonly used with wood shakes.

Interlocking shingles: individual shingles that lock together mechanically to enhance resistance to wind without depending on sealing strips.

Internal Pressure: the prevailing atmospheric pressure within a structure that relates to the quantity and distribution of openings and airflow leaks.

Inverted roof membrane assembly (IRMA™): a unique, patented variation of the conventional “protected membrane roof assembly” where Styrofoam® insulation and ballast are positioned atop the roof membrane. IRMA™ and Styrofoam® are registered trademarks of the Dow Chemical Company.

IRA (Inflation Reduction Act): The Inflation Reduction Act (IRA) is a US federal law that combats climate change by providing tax credits for clean energy technologies. This could increase demand for “cool roofs” and green roofing options, enabling roofers to offer new services to clients seeking tax benefits and a reduced carbon footprint.

ISANTA: International Staple, Nail & Tool Association.

Isocyanate: an extremely reactive organic compound characterized by the presence of one or more isocyanate (-N=C=0) groups, fundamental to systems based on SPF and select polyurethane coatings.

Isolation sheet: refer to slip sheet.

J

Joint Tape: adhesive tape used for sealing joints between insulation boards.

Joist: small beams, either wooden or metal, arranged parallel to one another and spanning from wall to wall to support the building’s floor, ceiling, or roof.

Joule: a measurement unit of energy or work; defined as the work done by a force of 1 newton acting over a distance of 1 meter in the direction of the force.

K

K or K-Value: a measure of thermal conductivity; quantified as the rate of heat transfer through a unit area of a material in a direction perpendicular to isothermal planes under a unit temperature gradient. In English units, it refers to the number of BTUs that cross through a 1-inch thickness of a 1-square-foot sample of material in an hour when there is a 1°F temperature difference across its surfaces. Expressed as Btu·inch/h·ft2·°F.

Kerf: (1) a slit or notch made by a saw or cutting torch; (2) the breadth of the cut made by such tools.

Kesternich test: evaluates rust and corrosion properties by reproducing acid rain conditions through exposure to a sulfur dioxide environment, coupled with condensed moisture.

Knee cap: a metal trim piece utilized to cover a panel rib post-cut and bending.

Knee joints: refer to Knuckle.

Knuckle: a metal closure, either factory-made or custom-fabricated, used over the cut seam of a continuous metal roof panel at the juncture of a steep-slope roof and a vertical component like a wall.

L

“L” flashing: a continuous metal flashing comprised of several feet of metal, commonly bent to form an “L” shape, employed at horizontal wall intersections.

Laitance: a fragile layer of cement and fine aggregates found on a concrete surface, often resulting from an excessively wet mixture, overworking, improper finishing, or a combination of these factors.

Laminate: the method of applying layers of materials together through fusion; a technique of joining material layers using adhesive methods.

Laminated shingles: refer to Dimensional shingles or Architectural shingles.

Lap: the component of roofing, waterproofing, or flashing that overlaps or conceals part of the same or an adjacent component.

Lap cement: a specialized asphalt-based roofing cement designed for bonding overlapping plies or asphalt roll roofing.

Lap seam: the point where overlapping materials are joined, sealed, or otherwise fastened.

Latex: a stable dispersion of polymeric materials within an essentially water-based medium.

Lead: a dense, malleable metal with a low melting point and a high thermal expansion coefficient.

Leader head: refer to Conductor head.

Leader Pipe: a conduit responsible for transporting water from gutters, scuppers, drop outlets, or other drainage units from the roof down to the ground level. Also referred to as a Downspout.

Lift: the resultant polyurethane foam generated from a specific pass. It typically consists of a designated pass thickness with a structured makeup of a bottom layer, central mass, and upper skin.

Liquid-applied: refers to the application of bituminous cements, adhesives, or coatings that are applied at room temperature or slightly elevated temperatures.

Liquid-applied built-up roof: a seamless, semi-flexible roofing membrane formed from multiple layers of felts, mats, or fabrics adhered together with alternating layers of roofing cement and topped with a liquid-applied coating, possibly with aggregate surfacing.

Live loads: temporary forces that a roof structure is engineered to withstand, as specified by applicable building codes. These loads are typically dynamic or environmental, such as people, equipment, snow, ice, or rainfall.

Loose-laid membrane: a ballasted roofing membrane that is adhered to the substrate solely at its edges and at points where it penetrates the roof.

Low-slope roofs: a classification of roofs that generally involves weatherproof membrane roof systems installed at slopes of 3:12 (14 degrees) or less.

Low temperature flexibility: the capacity of a membrane or material to avoid cracking when bent after being cooled to a lower temperature.

M

Material Safety Data Sheets (MSDS): documentation detailing the chemical composition of a product, provided by the manufacturer, including necessary safety protocols and emergency procedures.

MBMA: Metal Building Manufacturers Association.

MCA: Metal Construction Association.

Malarkey Roofing: Malarkey Roofing Products is a family-owned company that manufactures asphalt shingles and various roofing products. They offer eco-friendly, durable shingles in styles like architectural, designer, and 3-tab, made from recycled materials.

Mansard: a decorative roof feature characterized by steep slopes along a building’s perimeter.

Mansard roof: a roof with a pronounced steep pitch that transitions into a flat section at its peak.

Masonry: a construction method involving the use of natural stone or manufactured materials, such as brick, concrete blocks, adobe, glass blocks, tile, engineered stone, or gypsum blocks, typically joined with mortar.

Mastic: a thick adhesive substance utilized as a cementing agent for securing waterproofing membranes in place (refer to Asphalt roof cement).

Mat: a thin layer composed of woven, non-woven, or knitted fibers, functioning as reinforcement for materials or membranes.

Mat slab: a reinforced concrete slab designed to withstand uplift forces generated by hydrostatic pressure.

Mechanical damage: in relation to SPF-based roofing, physical harm to a completed SPF roof system excluding ordinary wear and tear.

Mechanical Fasteners: devices such as screws, plates, battens, nails, or other components used to secure roofing materials in place.

Mechanically fastened membranes: generally describes membranes attached at specified intervals to the underlying substrate.

Membrane: a flexible or semi-flexible roofing or waterproofing cover whose primary role is to prevent water ingress.

Metal: a category of materials that are generally opaque, ductile, fusible, and often shiny; known for their efficiency in conducting heat and electricity.

Metal Flashing: components made from sheet metal used to delineate the outer limits of the roofing membrane or material along the roof’s edges, also relevant around roof penetrations.

Meter: the metric unit measuring length, equivalent to 39.37 inches.

Mil: a unit measuring thickness equal to 0.001 inches (1/1000 inch), commonly used to specify the gauge of a roofing membrane.

Mildew: a superficial layer or staining of organic substances caused by fungi, especially prevalent in damp conditions.

Millimeter: a metric unit of measurement equal to one thousandth of a meter, or approximately 0.03937 inches.

MIMA: Mineral Insulation Manufacturers Association.

Mineral Fiber: inorganic fibers made from glass or rock materials.

Mineral Granules: see Granules.

Miter: a joint formed by the intersection of two diagonally cut pieces.

Model Codes: a compilation of accepted codes and standards recognized by multiple building code regulatory bodies, including SBCCI, BOCA, and ICBO.

Modified Bitumen: a type of bitumen that has been altered through the addition of one or more polymers, such as Atactic Polypropylene (APP) or styrene butadiene styrene (SBS).

Moisture Relief Vent: a vent incorporated into the roofing membrane to alleviate trapped moisture vapor pressure within the roofing system.

Moisture Scan: an evaluation process for detecting moisture levels in a roof, utilizing devices like capacitance meters, infrared cameras, and nuclear scanners. Infrared scans can be performed from above or directly on the roof surface, with nuclear scans being noted as particularly accurate.

Mole Run: a term used to describe an irregular ridge in a roof membrane not attributable to misaligned decking or insulation joints.

Monsoon Season: In Arizona, the monsoon season from June to September brings humidity, thunderstorms, and intense rainfall, significantly impacting the local ecosystem and hydrology. This period is vital for restoring water sources and promoting wildflower growth, highlighting the need for effective disaster preparedness and resource management.

Monolithic: describes materials or structures formed from a single continuous entity without seams.

Monomer: a basic molecule capable of bonding with other molecules to create a polymer.

Mop-and-flop: a roofing application technique where elements such as insulation boards or felt are first laid upside down near their final placement, coated with adhesive or bitumen, and then flipped over for proper adherence to the substrate.

Mopping: the technique of applying hot bitumen to a substrate or layers of a bituminous membrane using a mop or mechanical applicator, with four distinct methods:
– Solid mopping: applying a continuous layer of bitumen.
– Spot mopping: bitumen is applied in circular patches, leaving uncoated sections in a grid pattern.
– Sprinkle mopping: bitumen is randomly shaken onto the substrate using a broom or mop.
– Strip mopping: bitumen is layered in uniform parallel bands.

Mortar: a composite of sand, gravel, limestone, and water used to bond bricks in chimney construction.

Mud cracking: surface fissures resembling a dried mud flat.

Mud slab: a concrete layer, usually between 2 inches (50 mm) and 6 inches (150 mm) thick, serving as a foundational substrate for waterproofing membranes.

Multiple Coats: The application of more than one layer of coating to a surface.

N

NAHB: National Association of Home Builders.

Nail-guide-line: A painted mark on laminated shingles, facilitating proper fastener placement.

Nailing Pattern: A specific technique indicating how nails are to be applied, such as in base sheets on plywood roofs, where it may be described as “Nine and Eighteen”; meaning one row of nails positioned 9 inches on center along the edge, with two additional rows at the center spaced 18 inches on center.

Nail-pop: An occurrence where a nail is insufficiently driven, causing it to protrude above the roof deck.

Nailer: Sometimes known as blocking, refers to segments of lumber or plywood secured to structural decks or walls, providing a base for attaching membranes or flashings with fasteners.

NBP: Acrylonitrile butadiene polymer blend. One common proprietary NBP membrane is recognized as nitrile butadiene copolymer.

Negative side waterproofing: A waterproofing application where the system and the hydrostatic pressure source are directed opposite each other.

Neoprene: A synthetic rubber (polychloroprene) used in both liquid and sheet-applied elastomeric roof membranes and flashings.

Nesting: (1) Installing a new metal roof deck atop an existing one; (2) a reroofing technique where new asphalt shingles are laid over existing ones, aligning the new shingle’s top edge with the bottom of the existing shingle.

Net free vent area: The total area (in square inches) open to unrestricted airflow, used to gauge relative vent performance; calculated as the vent opening area minus any space occupied by screening materials.

Newton (N): The standard unit of measurement for force in the International System of Units.

Night seal (or night tie-in): A method or material for temporarily sealing the edge of a membrane during construction to safeguard the roofing assembly from water infiltration. Typically removed when work resumes.

NICA: National Insulation Contractors Association.

NIST: National Institute of Standards and Technology.

Ninety-Pound: Roofing material, including granule-surfaced, fiberglass, or organic felt roll, weighing approximately 90 pounds per 100 square feet.

Nitrile alloy: A synthetic elastomer created from non-vulcanizing polymers.

Nitrile rubber: A membrane primarily composed of synthetic rubber produced through the polymerization of acrylonitrile and butadiene.

Noble metal: A metal that readily gains electrons from a counterpart anodic metal (refer to the Galvanic series).

No-cutout shingles: Shingles that are made from a single solid strip, lacking cutouts.

Non-Breathing Membrane: A type of membrane that does not allow the passage of water vapor or air.

Nondestructive testing (NDT): Techniques used to assess the properties, structural integrity, or composition of materials or systems without inflicting damage. Commonly employed to measure moisture levels in roofing structures, utilizing methods such as electrical capacitance, infrared thermography, and nuclear backscatter.

Nonflammable: A material that is difficult to ignite and does not burn rapidly once ignited.

Nonfriable: A substance that cannot be easily crumbled, powdered, or pulverized by manual pressure when dry.

Nonoxidizing: A material that is resistant to oxidation in external exposure or accelerated weathering conditions.

Non-traffic bearing: A waterproofing membrane system that necessitates a form of protective barrier and surface wearing for its integrity.

Nonvolatile content: The portion of a coating that remains after drying or curing under specified conditions, consisting of the binder and, if applicable, the pigment. To determine the percent volatile content, subtract the nonvolatile content from 100.

Nonwoven fabric: A textile structure formed by bonding or interlocking fibers through mechanical, chemical, thermal, or solvent methods.

Nosing: Metal flashing bent at a 90-degree angle, installed around roof edges, curbs, platforms, etc., to safeguard the roofing system’s edge. Not intended to replace drip edge.

NRCA: National Roofing Contractors Association.

NTRMA: National Tile Roofing Manufacturers Association.

Nuclear hydrogen detection (NHD) meter: A device with a radioactive source that emits high-velocity neutrons into roofing systems; reflected neutrons are measured to detect hydrogen, with quantities linked to water pressure.

Nylon: A generic term for a category of polyamide polymers often employed as a scrim in certain fabric-reinforced sheeting.

O

Off-ratio foam: Spray Foam (SPF) that contains an excess of isocyanate or resin, which may not exhibit the full physical characteristics of standard SPF.

Open time: The time interval after an adhesive is applied and allowed to dry, during which an effective bond can still form by joining two surfaces.

Open valley: A valley construction technique where steep-slope roofing on both sides is trimmed along the valley, revealing the metal valley flashing.

Orange peel surface texture: In SPF roofing, a condition characterized by a fine-textured surface resembling that of an orange skin, acceptable for receiving protective coatings.

Organic: Comprising hydrocarbons or their derivatives, or materials derived from plant or animal origins.

Organic felt: An asphalt roofing base material made from cellulose fibers.

Organic mat: A material fabricated from recycled wood pulp and paper.

Organic shingle: An asphalt shingle reinforced with cellulose fiber material.

ORNL: Oak Ridge National Laboratory.

OSB: Oriented Strand Board, often selected as an alternative to plywood for roof sheathing.

Osmosis: The movement of a solvent through a semipermeable membrane into a solution with a higher solute concentration, aimed at equalizing solute concentrations on either side of the membrane.

Overflow drainage: A component in a roof drainage system designed to mitigate damage from water loads due to a blocked primary drainage system, such as an overflow scupper or interior drain.

Over-driven: A term for fasteners that have been pushed through roofing materials with excessive force, compromising their integrity.

Over-exposed: The installation of shingle courses higher than the intended exposure level.

Overlay: Refer to Re-Cover.

Overspray: Unwanted deposits resulting from airborne spray.

Overspray surface texture: A condition in SPF roofing where the foam exhibits a linear coarse texture or a pebbled finish, typically occurring downwind from the sprayed polyurethane path and, if pronounced, may hinder proper coating coverage and protection.

Owens Corning: Owens Corning is a leading American company producing roofing solutions and insulation materials. Known for reliability and innovation, it impacts the entire supply chain, fostering trust among contractors. The diverse product line adapts to market demands, enhancing the construction landscape and benefiting a broad network of clients.

Owens Corning Pick Your Shingles Roof Visualizer: A roof visualizer allows you to preview how a new roof will look on your home. You can choose colors and compare different shingle styles to make the best decision.

Ozone: A triatomic oxygen form, it appears as a bluish gas with a pungent smell, formed naturally in the upper atmosphere through photochemical reactions involving solar ultraviolet radiation.

Ozone resistance: The capacity of a material to withstand the damaging effects of ozone exposure.

P

Pallet: A typically wooden platform utilized for storing and transporting materials.

Pan: The flat, lower section of a roofing panel situated between its ribs.

Pan former: Equipment used for power roll-forming that shapes metal roofing panels from flat sheets.

Pan Flashing: A sheet metal flashing covering an equipment platform, designed to counter-flash the base flashings surrounding the platform.

Parapet wall: A portion of a wall that rises above the level of the roof.

Parge: In masonry, a cement mortar coating applied to rough masonry surfaces, earth-side foundation, and basement walls.

Partially attached: A roofing assembly where the membrane is secured in spots to a substrate, commonly with adhesives or mechanical devices.

Parting agent: A substance applied to one or both surfaces of a sheet to prevent sticking or blocking.

Pascal: A unit in the International System of Units representing force per unit area; 1 Pa = 1 N/m².

Pass: (1) A layer of material applied using a spray method, allowed to cure before subsequent layers are added; (2) Refers to the action of the foam gun during SPF application, where the speed of the motion governs the thickness of the foam.

Pass line: The intersection where two passes of SPF meet, marked by the top skin of the bottom pass and the adhering next layer.

Pedestal: A support base for rooftop components such as pavers, pipes, and small rooftop units.

Peel strength: The average load required to progressively detach a flexible component from a rigid or another flexible member per unit width.

Penetration: (1) Any structure (e.g., pipes, conduits, HVAC supports) that passes through the roof; (2) The degree to which a standard needle penetrates vertically into a sample of bituminous material under specified conditions, expressed in tenths of a millimeter (0.1 mm).

Percent Elongation: The maximum extent a material can be stretched before breaking, expressed as a percentage of its original length.

Perlite: An aggregate used in lightweight insulating concrete and preformed perlitic insulation boards, created by heating and expanding siliceous volcanic glass.

Perm: See Permeance.

Permeability: (1) The ability of a porous material to conduct or transmit fluids; (2) The rate at which vapor passes through a flat material at a defined thickness when subjected to a vapor pressure difference between two surfaces, under given temperature and humidity conditions. Measured in English units as gr/hr·ft²·(in. Hg/in.), commonly referred to as “perm·inch.”

Permeance: (1) The rate of water vapor transmission per unit area at a steady state through a material, membrane, or assembly; (2) The time rate of water vapor transmission through unit area of flat material or construction induced by a vapor pressure difference, measured under specific conditions. In English units, it is expressed in gr/h·ft²·in. Hg, referred to as “perm” units.

pH: A value indicating the acidity or alkalinity of a solution, with a neutral value of 7, lower values representing increasingly acidic conditions, and higher values indicating increasing alkalinity.

Phasing: A method involving the installation of roofing components in different time intervals. For example, laying a base sheet and then applying two roofing plies on one day, before returning to install two additional plies at a later time.

Phased application: The separate application of roofing or waterproofing system components over multiple intervals or days. Generally, surfacing applied at staggered times isn’t considered phased application. This reflects installing a roofing system without continuity.

Picture Framing: Rectangular shapes visible on a roof created by buckles or ridges in the roofing or dips in the underlying substrate.

PIMA: Polyisocyanurate Insulation Manufacturers Association.

Pinhole: A minute hole in coatings, foils, membranes, or other roofing materials.

Pipe Boot: A prefabricated flashing that seals around circular pipe penetrations, also termed a Roof Jack.

Pitch: A term referring to the angle of a roof slope, and also a shorthand for Coal Tar Pitch.

Pitch Pocket (or Pitch Pan): A flashing material encircling irregular roof penetrations, filled with grout and a pourable sealer to prevent moisture entry. Vulnerable to leaks, pitch pockets should be minimized.

Pittsburgh Lock Seam: A technique for securely interconnecting two distinct metal pieces.

Plastic Cement: Refers to Type I asphalt roof cement; avoid application on vertical surfaces. See also Asphalt Roof Cement and Flashing Cement.

Plastic Film: A malleable sheet created through the extrusion of thermoplastic resins.

Plasticizers: Substances added to rubber and plastic to enhance their flexibility and ease of use.

Plenum: An enclosed area where air or gas pressure exceeds that of the external atmosphere.

Plumbing Vents: Pipes extending through the roof plane for plumbing purposes, also known as vent stacks.

Ply: A layer of felt or a reinforcement material within a roofing system.

PMR: Refer to Protected Membrane Roof.

Polyester: A category of synthetic polymers formed primarily from the reaction of dibasic acids and dihydric alcohols, mainly used for their lightweight, strong, and weather-resistant properties. In roofing, polyester serves to reinforce fabrics.

Polyglass LS MAX Self Adhered Membrane: Polyglass is a self-adhered waterproofing membrane with a polyester reinforced surface. It features a dual compound self-adhesive system, allowing for easy application and quick watertight bonding. This flexible membrane can be used alone or as part of a multi-ply system with specific coatings for enhanced performance.

Polymer: A broad class of natural and synthetic compounds, typically of high molecular weight, made up of numerous repeated linked units, each a relatively small and simple molecule.

Polymer Modified Bitumen: See Modified Bitumen.

Polymeric Methylene Diphenyl Diisocyanate (PMDI): The “A” component in SPF systems; when combined with “B,” it generates polyurethane. PMDI is an organic compound containing two reactive isocyanate (-N=C=O) groups.

Polymerization: The process of linking monomers to create polymers.

Polypropylene: A variety of thermoplastic resins that are polymers of propylene, known for their toughness and rigidity, used in making molded products and fibers.

Polyurethane Foam Roof Installation: Polyurethane foam roofing is sprayed onto a roof, creating a thermal insulator and waterproof barrier. This method enhances energy efficiency, roof longevity, and requires minimal disruption. Its seamless application prevents leaks, providing a durable, eco-friendly solution that secures roof integrity in various weather conditions.

Polyvinyl Chloride (PVC): A thermoplastic polymer that is adaptable into either flexible or rigid forms with the help of plasticizers, stabilizers, fillers, and other modifiers; rigid forms are utilized in piping, while flexible forms are employed in sheeting and roofing membrane production.

Ponding: The excessive gathering of water in low-lying areas on a roof that persists for over 48 hours after rainfall under favorable drying conditions.

Pop Rivet: A small-headed pin designed to join light gauge sheet metal through an expandable head.

Popcorn Surface Texture: In SPF roofing, it refers to a coarse surface texture of foam where valleys form sharp angles, considered inadequate for proper coating and protection.

Positive Drainage: A drainage condition ensured during design, accounting for all loading deflections of the deck, with additional roof slope included to facilitate drainage within 48 hours following rainfall when conditions are favorable for drying.

Positive Side Waterproofing: An application where both the waterproofing system and the source of hydrostatic pressure are on the same side of a structural element.

Pot Life (Working Life): The timeframe during which a reactive mixture remains suitable for its intended processing after the introduction of initiating agents.

Pourable Sealer: A sealant, typically supplied in two parts, used at challenging-to-flash penetrations, often in conjunction with pitch pockets to establish a watertight seal.

Power Vents: Electrically-driven fans designed to expel air from attics and other structures.

Press Brake: A tool used for the cold-forming of sheet metal or strips into specific profiles.

Prestressed Concrete: Concrete in which reinforcing cables, wires, or rods are tensioned prior to loading, thereby maintaining the concrete in a compressed state for enhanced strength.

Pre-Tinning: The act of applying a coating of solder or tin alloy on metal before the soldering or brazing process.

Prevailing Wind: The most frequently occurring wind direction in a given area.

Preventing Roof Damage During Monsoon: Prevent roof damage during Tucson’s monsoon season by inspecting for weaknesses, trimming overhanging branches, and considering emergency repairs. Use durable tarps on vulnerable areas.

Primer: (1) A thin, solvent-based liquid bitumen applied to surfaces to improve the adhesion of subsequent bitumen applications; (2) A material sometimes utilized in seaming single-ply membranes to prepare surfaces and increase splice strength; (3) A thin liquid-applied substance that enhances the adhesion of following SPVF protective coatings.

Proportioner: The fundamental pumping unit for SPF or two-component coating systems, consisting of dual positive displacement pumps that dispense two components at a precisely controlled mix ratio.

Protection Course: A sacrificial layer used to protect a waterproofing material from detrimental external forces.

Protection Mat: A sacrificial layer that shields one component of a roofing system from another.

Protected Membrane Roof (PMR): An insulated and ballasted roofing solution where insulation and ballast are situated atop the membrane, often referred to as an “inverted roof assembly.”

Psychrometer: An instrument designed to gauge humidity in the atmosphere utilizing two similar thermometers; one with a wet bulb and the other dry.

Psychrometric Chart: A chart illustrating the correlation between dew point temperature, dry bulb temperature, wet bulb temperature, and relative humidity.

Puncture Resistance: The capacity of a material to endure the impact of a piercing or puncturing entity.

Purlin: A horizontal secondary structural element that conveys loads from the primary structural framework.

PVC: Polyvinyl Chloride.

Q

Nothing Here click here to scroll to top of page.

R

R-value: See Thermal Resistance.

Racking: A method of applying asphalt shingles, known as the straight-up method, whereby shingle courses are installed vertically rather than laterally.

Rafter: The structural component extending from the downslope edge of a roof to its ridge or hip, designed to support the roof deck and system elements.

Raggle: A groove cut into the side of a vertical surface, such as a wall or chimney, for inserting a flashing element like a reglet or counterflashing.

Rake: The angled perimeter edge of a roof that extends from the eaves to the ridge, typically perpendicular to both.

Rake Edge: The vertical edge of roofs styled gable.

Rake-Starter: A starter strip positioned along rake edges for asphalt shingle roofing applications. See also Bleeder Strip.

RCI: Roof Consultants Institute.

RCMA: Roof Coatings Manufacturers Association.

RDCA: Roof Deck Contractors Association.

Re-Cover (Overlay): The act of placing a new roofing system over an existing system without removing the old one.

Recycled Asphalt Shingles: A sustainable asphalt shingle lifecycle is crucial for reducing environmental impacts. Certain roofing manufacturers are leading innovations in recycling, transforming discarded shingles into new materials, minimizing waste, conserving resources, and lowering emissions. Continued advancements in recycling technology and consumer awareness are vital for a greener future in roofing.

Reglet: A sheet metal component that serves as a receiver for counterflashings, which can be surface-mounted, set in a raggle, or integrated into wall assemblies.

Reinforced Membrane: A roofing membrane enhanced by the inclusion of polyester scrims or mats, glass fibers, or other materials.

Relative Humidity: The ratio of water vapor present in the air to the maximum amount that can be held at a specified temperature. For instance, a relative humidity of 50% indicates the air holds half of the moisture it could potentially accommodate at that temperature.

Release Film: The plastic sheet on the back of Weather Watch® and StormGuard® underlayments, used for packaging and handling; must be removed prior to installation.

Remove and Reinstall: The process of detaching a component for reuse through reinstallation.

Remove and Replace: The act of taking out a component and substituting it with a new, similar component.

Re-Roofing: The process of installing a new roofing system.

Resin: The “B” component in SPF that combines with the “A” component to create polyurethane. Resin comprises a catalyst, fire retardants, a blowing agent, Polyol, and a surface active agent.

Ridge: The highest point on the roof where two sloping surfaces meet, extending the entire length of the roof.

Ridge Cap: Material installed over the ridge or hip of a roof for protection.

Ridge Course: The concluding layer of roofing that covers the intersection areas of multiple roof planes.

Ridge Vent: Exhaust venting apparatus positioned at the roof ridge, designed to work alongside a starter or under eave soffit vent to ventilate attics. Proper function requires a 1:1 installation ratio with starter or soffit vents.

Ridging: The creation of a buckle in roofing material.

RIEI: Roofing Industry Educational Institute.

Rigid Vent: Durable plastic ridge vent material.

RMA: Rubber Manufacturers Association.

Roof Assembly: A coordinated collection of roofing elements, including the roof deck, vapor retarder (if applicable), insulation, and roofing covering.

Roof Cement: See Asphalt Roof Cement or Coal Tar Roof Cement.

Roof Covering: The external layer of the roof assembly, made up of membranes, panels, sheets, shingles, tiles, etc.

Roof Curb: An elevated frame to support mechanical units (like air conditioning or exhaust fans), skylights, etc., on the roof.

Roof Donation: Contributions to roofing projects can come from contractors, charities, and nonprofits, providing materials, labor, and volunteer hours. These donations foster community support and resilience, turning sustainable practices into collective efforts that uplift those facing housing challenges.

Roof Leak: Water penetration occurs when damaged areas on your roof let water in, often seen as stains on ceilings or walls. Causes include damaged shingles, faulty flashing, clogged gutters, cracked valleys, or weather events like hailstorms.

Roof Louvers: Rectangular vents located on the roof, also known as box vents, mushroom vents, airhawks, or soldier vents.

Roof Jack: A metal or wooden bracket used to hold toe-boards in place on steep-slope roofs. (See also Flashing Collar.)

Roof Overhang: The portion of the roof that extends beyond the main exterior walls of a building.

Roof Plane: A defined section of roofing with four distinct edges, characteristic of gable, hip, or mansard roofs.

Roof ROI (Return on Investment): ROI, or return on investment, measures the gain or loss from an investment relative to its cost, expressed as a percentage. For a new roof, ROI can range from 48.9% to 68.2%, with homeowners recouping about 60% to 70% when selling their home.

Roof Seamer: (1) A machine that crimp neighboring metal roof panels together; (2) A machine that welds membrane sheet overlaps using heat, solvent, or dielectric energy.

Roof Slope: The angle formed between a roof surface and the horizontal plane, expressed as a ratio of vertical rise to horizontal run (sometimes referenced as run). In English measurements, dimensions in inches can be represented as a rise-to-run ratio, e.g., 4:12, or as an angle.

Roof System: A collection of interrelated roofing components, typically including a membrane or primary roof covering and roof insulation (excluding the roof deck), engineered to be weather-resistant and potentially enhance the building’s thermal performance.

Roofer: A professional specializing in the installation of roof systems and materials.

Rosin Paper: Specifically, Rosin-sized sheathing paper; a non-asphalt based sheet utilized as sheathing paper or slip sheet in specific roofing systems.

Rubber: A versatile material that can rapidly recover from significant deformations.

Run: The horizontal dimension of a slope.

Rust Blush: The initial stage of rust, marked by a reddish or orange tint.

S

Sawteeth: The visible section of dual-thickness on Timberline® Series shingles, designed to emulate the appearance of wood shake roofing.

SDI: Steel Deck Institute.

Saddle: A small tapered or sloped roofing structure that directs surface water toward drains, commonly found in valleys. This structure resembles a small hip roof or pyramid with a diamond-shaped base. (See also Cricket.)

Sag: An undesirable phenomenon where material excessively flows post-application onto a surface.

Saturated Felt: A type of felt that has been saturated in hot bitumen, absorbing as much as it can under processing conditions while remaining porous.

SBCCI: Southern Building Code Congress International, Inc.

SBS: See Styrene Butadiene Styrene.

Scarfed: Shaped through the grinding process.

Screeding: The technique of removing excess concrete to achieve the desired surface finish and level.

Screen Wall: A non-structural partition built around roof units or curbs, with framing typically consisting of girts and a wood or metal covering.

Scrim: A woven, nonwoven, or knitted textile made of continuous material strands, used for reinforcing or strengthening membranes.

Scupper: A drainage feature that allows water to exit through a wall, parapet wall, or elevated roof edge, usually lined with a soldered sheet metal sleeve.

Scuttle: A hatch granting access to the roof from within the building.

Sealant: A general term encompassing various materials used to seal joints or seams against moisture or weather intrusion.

Sealer: A coating formulated to prevent bleed-out or bleed-through.

Seam: A line, ridge, or groove formed from the joining, fitting, or lapping of two sections.

Self-Adhering Membrane: A membrane whose underside adheres to a substrate without the need for additional adhesive.

Self-Drilling Screw: A screw equipped with a drill-bit-like tip, capable of drilling its own hole and negating the necessity for pre-drilling.

Self-Sealant: Sealant incorporated onto shingles that activates after installation through heat and sun exposure, bonding the shingles together.

Self-Sealing Shingle: Asphalt shingles featuring adhesive strips that soften and bond to the subsequent layer when heated by sunlight, aimed at preventing wind uplift.

Self-Tapping Screws: Fasteners designed to create their own threads when driven into a hole.

Self-Vulcanizing Membrane: A type of membrane that starts as thermoplastic and cures after installation.

Selvage: The area on rolled roofing that is not exposed, left granule-free for nail placement and sealant application.

Selvage Edge: The portion of a granule-surfaced membrane intended to overlap with the adjacent membrane course, typically measured at two, four, or nineteen inches wide.

Shark Fin: A curled edge or overlap in a membrane.

Shed Roof: A roof consisting of a single sloping plane, also referred to as a Half Gable.

Shelf Life: The duration between a material’s manufacturing and when it ceases to be suitable for use.

Shiner: A term describing an exposed nail that remains uncovered by the next layer of roofing material.

Shingle: (1) A singular piece of prepared roofing material, either asphalt or wood, utilized in steep slope roofing systems; (2) The action of installing a wood or asphalt shingle roof system.

Shingle Roof Installation: Installing a shingle roof involves covering a structure with flat, rectangular shingles made from materials like asphalt or composites. Consider aesthetics, durability, and maintenance needs. Engaging professionals ensures the best materials for your climate and helps avoid DIY pitfalls, enhancing both curb appeal and protection against the elements.

Shingle Fashion: Pertains to the method of overlapping identical materials to achieve layered coverage.

Shrinkage: The process resulting in a decrease in size; contraction.

Shrinkage Crack: A fissure that develops due to material contraction. This may stem from thermal expansion/contraction, material failure, or curing processes.

SI: The international measurement system (metric). Système International [d’Unites].

Side Lap: The longitudinal overlap of adjacent materials.

Side-Walls: The areas where a vertical roof plane aligns with a vertical wall, commonly found in dormer structures.

Siding: Materials used for the external finish of a structural wall.

Sill: The bottom framing component of a door or window opening.

Sill Flashing: Flashing material intended to waterproof the bottom framing of a door or window opening.

Single Coverage: The application of just one layer of roofing material.

Single-Lock Standing Seam: A standing seam system characterized by a single overlapping connection between two seam panels.

Single-Ply Membranes: Roofing membranes that are installed as a single layer. These can be thermoplastic or thermoset in nature, categorized into five basic types: (1) Ballasted, (2) Fully-Adhered, (3) Mechanically-Fastened, (4) Partially-Adhered, and (5) Self-Adhered. The seams can be welded through heat, solvents, or adhesives.

Single-Ply Roofing: Roofing systems wherein the primary material comprises a single-ply membrane.

Skylight: A transparent or translucent element designed to allow light entry, positioned over a curved opening in the roof.

Slag: Residual material from blast furnaces occasionally utilized as a surfacing agent on aggregate-surfaced built-up roofing systems.

Slate: A finely structured metamorphic rock that can be split into thin, smooth layers, commonly used in steep slope roofing applications.

Slating Hook: A hook-like tool employed to secure roofing slate in place.

Slip Sheet: A sheeting material placed between roofing components to prevent adhesion between them or to avoid material damage from component incompatibility. Slip sheets can be made from polyethylene, rosin-sized sheathing paper, or similar materials.

Slit Sample: A measurement cut made in SPF roofing to determine coating thickness, typically about 1.5 inches long by _ inches deep by _ inches wide.

Slope: The angle of a roof’s incline expressed as a percentage or as a ratio of rise to run. Refer to Roof Slope for further details.

SMACNA: The Sheet Metal and Air Conditioning Contractors National Association.

Smooth Surface Texture: In SPF roofing, a surface texture that is relatively smooth and considered ideal for accepting base coatings.

Smooth Surfaced Roof: A roof characterized by having no surfacing material or featuring a smooth surface treatment such as emulsion and/or a reflective coating.

Snow Guard: Devices installed on roofs to help retain snow and ice, preventing them from sliding off.

Snow Load: The additional weight a roof must bear due to accumulated snowfall, a crucial structural factor in regions that experience heavy snow.

Soffit: The lower surface of a roof overhang.

Soffit Vent: An intake vent positioned within the soffit, paired with an exhaust vent near the roof’s peak for effective attic space ventilation. An ideal ratio of intake to exhaust vent area is 1:1.

Softening Point: The temperature threshold at which bitumen begins to flow.

Softening Point Drift: Variations in the softening point of bitumen; also see Fallback.

Soil Pipe: A pipe that projects through a roof to ventilate a building’s plumbing system.

Solder: Various fusible alloys, often a combination of tin and lead, used to connect metal components.

Solid Mopping: The continuous application of hot asphalt or coal tar, ensuring no areas are left bare of bitumen.

Solvent: (1) A liquid capable of dissolving substances like bitumen. (2) A liquid within a substance that aids in its application, evaporating after use and leaving the desired working characteristics. Solvent-based adhesives and mastics serve as examples.

Solvent Weld: The process of joining materials through the use of a liquid solvent.

Spall: A chip, flake, or fragment that breaks off from concrete or masonry surfaces.

Special Steep Asphalt: Roofing asphalt that meets the specifications established by ASTM Specification D 312, Type IV, suitable for roofs with slopes up to 6 in 12 (50%).

Specification: Documented guidelines for a construction initiative, detailing the scope of work, construction methods, and materials required.

SPF: Sprayed Polyurethane Foam.

SPF Compounds: Refers to the isocyanate and resin elements involved in the creation of polyurethane foam.

SPI: The Society of the Plastics Industry.

SPI/SPFD: The Society of the Plastics Industry/Sprayed Polyurethane Foam Division.

Splash Guard: A metal or masonry component positioned beneath a leader pipe or downspout to shield the roof membrane at a lower level or to mitigate soil erosion when placed on the ground.

Splice: To join two materials by overlapping their ends.

Splice Plate: A metal sheet positioned under the junction of two metal pieces.

Splice Tape: A double-sided adhesive tape used to join membrane materials.

Split: The division of a material resulting from tensile pressure.

Sprayed Polyurethane Foam (SPF): A cohesive sprayed-on roofing material with a high R-value, formed from a blend of isocyanate (“A” component) and resin (“B” component) in a 1:1 ratio.

SPRI: Single Ply Roofing Institute.

Sprinkle Mopping: The technique of scattering hot bitumen across a surface.

Spud: The action of scraping the top layer of a roof surface down to the membrane using specialized tools known as spud bars or power spudders.

Spud Bar: A long-handled tool equipped with a rigid flat blade on one end (commonly 4” or 6” wide) used for scraping and removing the upper surfacing of a roof down to the membrane.

Spunbond: Refers to nonwoven fabrics created from continuously bonded fibers.

Spunlaced: Describes nonwoven fabrics where fibers are interwoven using a water jet method.

Square: (1) An area covering 100 square feet of roofing (9.29 m²) in the United States. (2) An area of 10 square meters (107.639 ft²) under the metric measurement system.

Stack Effect: The phenomenon where warm air escapes from higher openings in a building, drawing in cooler outside air through lower openings. In roofing, this effect facilitates ventilation in attic or roofspace areas and is influenced by atmospheric conditions, such as temperature and wind.

Stainless Steel: A steel alloy noted for its high corrosion resistance, typically containing chromium, nickel, or copper.

Stair Step: A method of laying shingles diagonally.

Standing Seam: A metal roofing system style where adjacent panels have raised seams that are overlapped and folded to prevent moisture infiltration and to interlock the panels securely.

Starter Course: The initial layer of roofing materials laid along the downslope edge and typically covered by the first course of roofing.

Starter Plies: Felt or ply sheets cut to widths proportionate to the reciprocal of the number of plies being applied. For example, in a three-ply built-up roof, the first starter ply would be one-third of the roll width, the second would be two-thirds of the roll width installed over the first, followed by a complete ply atop those.

Starter Strip: Strips of shingles (commonly 3-Tab shingles with tabs removed) or roll roofing material laid along the eave line before the installation of the first course of shingles. This starter strip helps fill voids created by shingle cutouts and joint placements.

Static Load: Roof loads that remain stationary, such as HVAC units.

Steep Asphalt: Roofing asphalt compliant with ASTM Specification D 312, Type III, suitable for roofs with slopes up to 3 in 12 (25%).

Steep-Slope Roof: A roofing surface with a slope greater than 3 in 12 (25%), deemed appropriate for water-shedding roofing materials such as asphalt shingles, wood shakes, and concrete or clay tiles.

Steep-Slope Roofing Materials: Roofing materials that rely on their water-shedding features to prevent moisture intrusion in structures. These materials are typically installed on roofs with slopes reaching or exceeding 3” in 12” (25%).

Steeple: A tall structure that comprises the upper part of a building, such as a church or temple, often crowned with a spire.

Step Flashing: Individual pieces of metal or similar materials used to flash projections from the roof, such as chimneys or walls. These pieces are typically inserted between each course of roofing and generally feature one vertical flange equal in length to the corresponding horizontal flange.

Strapping: A method of installing roofing felts parallel to the slope, although not advised for slopes at a 1:12 ratio or less.

Straw Nail: Long-shanked nails utilized to secure tiles along hips and ridges.

Strip Flashing: Membrane material pieces used to flash metal flashing flanges like gravel stops, also known as Stripping.

Strip Mopping: The application of hot bitumen in parallel lines.

Strip Shingles: Asphalt shingles produced in strips.

Styrene: A colorless oily liquid, C6H5CH:CH2, serving as the monomer for polystyrene.

Styrene Butadiene Styrene (SBS): The modifying agent incorporated into SBS modified asphalt roofing materials, imparting a rubber-like characteristic.

Substrate: The surface layer upon which roofing material is installed.

Sump: A recessed area surrounding roof drains and scuppers designed to facilitate water drainage.

Surface Erosion: The degradation of a surface caused by abrasion or exposure to the elements over time.

Surface Texture: The final appearance and quality of an SPF surface. Surface textures for SPF can vary, including options like Orange Peel Surface Texture, Coarse Orange Peel Surface Texture, Smooth Surface Texture, Verge of Popcorn Surface Texture, Popcorn Surface Texture, and Tree-Bark Surfaced Texture.

SWRI: Sealant, Waterproofing and Restoration Institute.

Surfacing: The upper layer or layers of a roofing system intended to safeguard the underlying materials from direct weather exposure.

Surfactant: A term for “surface active agent”; a substance that enhances the emulsifying, dispersing, spreading, wetting, or other surface-modifying characteristics of liquids.

Synthetic Underlayment: Synthetic underlayment is a modern roofing solution made from plastic, offering improved moisture protection and durability over traditional felt paper. Its lightweight design resists UV rays and punctures, making it a superior choice for maintaining the integrity and lifespan of roofs in today’s construction landscape.

T

Tab: The exposed section of strip shingles defined by openings or cutouts.

Tack-free time: In SPF roofing, this refers to the duration during which polyurethane foam cures until it is no longer tacky. Once tack-free, the foam can be applied with another layer, commonly known as a “lift.” With careful handling, it can be walked on shortly after this phase.

Talc: A fine, whitish powder utilized at manufacturing facilities, applied to the surface of specific roofing materials (such as vulcanized EPDM membranes) to act as a release agent, assisting in preventing adhesion.

TAMKO Building Products LLC: As a leading producer of residential roofing materials and moisture resistance solutions, this company has built a strong reputation for their diverse color options and superior quality. Their focus on innovation and design significantly enhances their status in the construction industry.

Tapered edge strip: An insulation strip with a tapered profile used to (1) elevate and slope the roof at the edges and around curbs and (2) facilitate a gradual transition between different layers of insulation.

Taping: (1) The method of connecting joints between insulation boards or deck panels using tape; (2) The technique of utilizing self-adhering tape-like materials to join or splice single-ply membranes.

Tar: A viscous brown or black substance that is either liquid or semi-solid, predominantly composed of bitumens that are extracted as condensates from coal, petroleum, oil shale, wood, or other organic materials.

Tar boils: Small bubbles of moisture vapor trapped within a thin layer of bitumen, also colloquially referred to as “blackberries.”

Tarred felt: A term synonymous with Coal tar felt.

Tear-off and reroof: The extensive process of stripping away all components of the roofing system down to the structural deck, followed by the complete installation of a new roofing system.

Tear resistance: The force needed to tear a material when stress is focused on a specific area due to an introduced flaw or notch. Measured in psi (pounds force) per inch of width or kN/m (kilonewtons per meter).

Tear strength: The maximum force required to tear a material specimen.

Tensile strength: The measure of a material’s capacity to withstand tension, distinct from torsion, compression, or shear.

Tension leveling: The technique of drawing metal coil stock between two spools under pressure to minimize side camber and prevent potential oil canning resulting from manufacturing and cutting processes.

Termination: The procedure or method for anchoring and/or sealing the free edges of a membrane within a roofing or waterproofing system.

Terne: An alloy formed from lead and tin, applied to carbon steel or stainless steel sheets for usage as a metal roofing material.

Terra cotta: A type of low-fired clay, which can be either glazed or unglazed.

Test cut: A sample taken from the roofing system or assembly that uncovers the roof deck, utilized to assess the condition of the membrane, the type and number of layers or membranes, or the rates of application (for instance, the weight of the average interply bitumen moppings).

Thermal block: A compressive insulation component installed between structural steel roof panels and their supporting members to enhance insulation R-values and reduce condensation.

Thermal bridge: The incursion of a material with high thermal conductivity (such as a metal insulation or roof membrane fastener) through a material with low thermal conductivity (like thermal insulation), resulting in lower thermal resistance for the assembly.

Thermoset: A category of materials that cannot be reshaped or reformed through heating processes, with EPDM and butyl being prominent examples.

Thinners: Solvents used to decrease the viscosity of a material upon mixing, evaporating during the curing phase.

Thixotropy: A characteristic of specific materials that liquefy when subjected to vibrational forces, such as stirring or shaking, and then revert to a solid state when undisturbed.

Throat: (1) The cutout section of a shingle; (2) The constricted passage found between a fireplace and its smoke chamber or flue.

Through-Wall Flashing: A material that extends through a wall, facilitating the drainage of water that infiltrates a wall cavity to the structure’s exterior.

Tie-In: The method of connecting two distinct roofing systems together.

Tie-Off: A watertight seal used to secure roof membranes at system adjuncts, terminations, flashings, or substrates. This can be either a temporary solution (refer to Night Seal) or permanent.

Tile Roof Installation: Tile roof installation involves securing individual tiles, made of clay, concrete, or slate, onto a roof deck, overlapping rows for a waterproof barrier. This process includes installing an underlayment for extra water protection, paying special attention to ridges and hips.

TIMA: Acronym for Thermal Insulation Manufacturers Association.

Toggle Bolt: A bolt featuring a separate toggle that can be compressed to fit through a pre-drilled hole, which then expands to provide secure fastening when tightened.

Tongue-and-Groove: Pre-manufactured materials designed with a protruding “tongue” on one side and a corresponding concave “groove” on the opposite for secure jointing of materials.

Torque: The force exerted on an object, particularly when fastening screws into a roof deck or substrate.

TPA: Abbreviation for Tri-Polymer Alloy.

Traffic: Any activity occurring on the rooftop that could potentially harm the roof’s surface.

Transitions: The points where two roof planes meet that have differing slopes or pitches.

Transverse Seam: The joint connecting the top of one metal roof panel to the bottom of the subsequent panel, oriented perpendicular to the slope of the roof.

Treebark Surface Texture: An SPF surface that is not deemed suitable for coating, featuring deep valleys akin to rough tree bark.

Tuckpointing: The practice of removing decayed mortar from existing masonry joints and replacing it with fresh mortar or another filler.

U

U-Value: Refer to Thermal transmittance.

UBC: Acronym for Uniform Building Code.

UL: Underwriters Laboratories, Inc.

UL label: A certification label or seal affixed to a roofing product or packaging by Underwriters Laboratories, signifying compliance with specific performance standards.

Ultraviolet (UV): Invisible radiation adjacent to the violet segment of the visible spectrum, with wavelengths ranging approximately from 200 to 400 nm (nanometers).

Ultraviolet Light (UV): A kind of radiant energy found in sunlight beyond the violet range, with wavelengths not visible to the eye. UV rays expedite the degradation of roofing materials, necessitating protective coatings.

Under-driven: A term describing a fastener that has not been fully recessed to sit flush with the shingle surface.

Underlayment: A sheet material, often asphalt-saturated felt or self-adhering, placed between the roof deck and roofing covering, primarily used in steep-slope roofing. It serves to separate the covering from the deck, shed water, and provide additional weather protection.

Underwriters Laboratories, Inc. (UL): An organization responsible for testing, rating, and classifying roof assemblies based on their resistance to fire, impact, leaks, corrosion of metal components, and wind uplift.

Uplift: Refer to Wind uplift.

V

Valley: The internal angle formed where two sloping roof planes converge.

Vapor migration: The movement of water vapor from an area of high vapor pressure to one of lower vapor pressure.

Vapor Retarder: A material designed to inhibit the flow of water vapor across a roof assembly.

Vapor pressure: The pressure exerted by a vapor in equilibrium with its corresponding solid or liquid phase.

Vapor retarder: A layer or laminate intended to significantly diminish the flow of water vapor into the roof assembly.

Veneer: (1) A single wythe of masonry used for facade purposes that may not be structurally connected; (2) Any thin layers of wood bonded together to form plywood.

Vent: An opening meant to allow the escape of air, heat, water vapor, or gases from inside a building or its components.

Ventilator: An accessory designed to facilitate airflow passage.

Ventilation Short Circuit: The interference of airflow within an intake-exhaust ventilation system. For example, if turbine vents or gable vents are located between the intake and exhaust vents (such as soffit and ridge vents), the draw created by the Stack Effect becomes disrupted, which significantly reduces the effectiveness of the ventilation system.

Verge of popcorn texture: In the context of SPF roofing, this surface texture represents the roughest acceptable condition for receiving a protective coating on a sprayed polyurethane foam roof, characterized by larger nodules compared to valleys, where the valleys are reasonably cured. While it may be acceptable for caulking due to the relatively cured valleys, it is generally considered undesirable due to the increased amount of coating material required for proper protection.

Vermiculite: An aggregate utilized in lightweight insulating concrete, produced by the heating and expansion of micaceous materials.

Viscosity: The measure of a material’s resistance to flow when subjected to stress. For bitumen, this measure is given in centipoise (see Viscous).

Viscous: Describing a material’s resistance to flow under stress.

Void: An open space or lack of consistency within a material.

Volatile: A term used to denote the propensity of a substance to transform into vapor.

Volatile organic compounds (VOC): Refers to any carbon-based compound, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides, carbonates, and ammonium carbonate, which can engage in atmospheric photochemical reactions.

Vulcanization: An irreversible chemical process wherein a rubber compound undergoes structural changes (such as cross-linking), enhancing its resilience against swelling by organic liquids and improving or extending its elastic properties over a wider temperature range.

W

WSRCA: Abbreviation for Western States Roofing Contractors Association.

Warm roof assembly: A configuration of roofing where each component is placed directly on top of the prior component, ensuring contact between adjacent parts without allowing space for ventilation. This is commonly known as a “compact” roof assembly.

Warm wall: The completed wall interior within a structure, utilized in roofing to dictate how waterproof underlayments should be installed at eaves.

Warranty: A formal written commitment to the roofing materials owner regarding material-related issues.

Wash coat: A primer typically applied to the backside of painted metal products to safeguard the underlying metal from wear and corrosion.

Water Absorption: The change in weight of a test specimen, expressed as a percentage of its dry weight after immersion in water for a specified duration at a defined temperature.

Water cure: A technique for curing materials, such as concrete, that involves misting the surface with water to control moisture evaporation rates.

Water cutoff: Refer to Cutoff.

Water Guard: An upturned edge on valley metal or continuous wall flashing utilized to hinder water from migrating beneath the roof system.

Water-shedding: The property of individual, overlapping components to resist water penetration without applied hydrostatic pressure.

Water stop: A diaphragm installed across a joint as a sealant, primarily to prevent water from passing through.

Water table: The level below which soil remains saturated with water.

Water Trough: The region in a valley where water flows, often referenced in open valley configurations.

Water vapor transmission: The rate at which water vapor moves through a material under controlled lab conditions regarding temperature and humidity, typically measured in grains/h·ft².

Waterproof: The characteristic of a membrane or material that effectively prevents water infiltration.

Waterproofing: The methodology applied to surfaces or structures to deter water intrusion under hydrostatic pressure.

Waterproof underlayments: Modified bitumen-based roofing underlayments engineered to tightly seal against wood decks and safeguard critical leak points.

Wear course: The uppermost layer designed to endure pedestrian or vehicular traffic, frequently referred to as the wearing surface.

Wearing surface: A term that refers back to the wear course.

Weather: To undergo degradation in quality and appearance as a result of exposure to environmental elements such as sunlight, wind, and rain.

Weatherproof: The capability of a membrane or roof covering to impede water infiltration under limited hydrostatic pressure.

Weep holes: Small openings designed to facilitate drainage of water accumulating within a building component (e.g., brick walls or skylight frames).

Weld: The process of joining metal pieces through heat fusion.

Wet: A state characterized by the presence of free water within a material.

Wet bulb temperature: The air temperature indicated by a thermometer whose bulb is encapsulated in a water-saturated wick.

Wet film thickness: The thickness, measured in mils, of a coating or mastic as applied but before it has cured. For reference, see Dry film thickness.

Wick: To draw liquid using capillary action.

Wicking: The process by which moisture moves through a material via capillary action.

Wind clip: A fastening device for steep-slope roofing that fits over the butt end of tiles, slates, and stones to secure roofing units against wind uplift.

Wind load: The force that wind exerts on a structure or component of a structure.

Wind uplift: The force generated by wind currents at roof edges, peaks, or obstructions that causes a drop in air pressure immediately above the roof surface.

Windward: The side exposed to the wind.

Wire tie system: A fastening system employed for steep-slope roofing units (e.g., tiles, slates, and stones), utilizing fasteners (nails and/or screws) combined with wire to create a concealed fastening mechanism.

Work slab: Refer to Mud slab.

Woven valley: A valley construction technique where shingles or roofing materials from each side of the valley overlap and interlace as they are applied.

Wythe: A masonry unit constituting a singular segment of a wall, generally measuring at least two inches thick.

X Y Z

Yield: In SPF-based roofing, the volume of foam produced per unit weight, typically expressed as board feet per pound or board feet per 1000 pounds.

Z section: A structural element formed in a “Z” shape from coils of steel stock.

Zinc: a robust, bluish-white metal that exhibits brittleness at standard temperatures but becomes highly malleable and ductile when heated; resistant to corrosion; commonly utilized for galvanizing sheet steel and iron, incorporated into various metal alloys, and used as an oxide in white paint pigment.