Roofing Terms Glossary

Architectural metal panel roof system - a water-shedding roof system composed of metal panels usually requiring a solid or closely spaced roof deck underneath for support. 

Architectural panel - a metal roof panel designed to be applied over a continuous or closely spaced roof deck. 

Architectural shingle - see laminated shingle 

Asphalt - a dark brown or black substance derived from crude oil or petroleum that is processed for use in various roofing and waterproofing applications. 

Asphalt shingle - a type of steep-slope roof covering manufactured by coating a reinforcing material with asphalt and having mineral granules on the side exposed to the weather. 

Batten seam - a metal panel seam formed around a beveled wood or metal batten. 

Bitumen - a generic term for any material primarily composed of asphalt or coal tar. 

Bituminous roof membrane - a weatherproofing membrane containing bitumen, such as asphalt or coal tar; either a built-up roof membrane or polymer-modified bituminous roof membrane. 

Building codes - the minimum construction requirements that are adopted and enforced by local governing authorities for the safety and welfare of buildings and their occupants. 

Building paper - a synthetic sheet material applied usually to exterior surfaces of wood framed structures prior to installing finished surfacing materials. 

Built-up roof (BUR) system - a job-site constructed roof membrane made of bitumen and felts in alternating layers with a surfacing. 

Butt edge - the bottom edge of an individual unit of a steep-slope roof covering material. 

Butt joint - a joint formed by adjacent, separate pieces of material. 

Cant strip - a beveled strip used under flashings to modify the angle at the point where the roofing or waterproofing membrane meets any vertical element. 

Cap sheet - a sheet, often granule-surfaced, used as the top ply of some built-up or polymer-modified bitumen roof membranes and /or flashings. 

Ceramic grannies - granules made by pulverizing dried ceramic materials of various colors that are used as the surfacing material for many roofing products. 

Clay tile - a type of steep-slope roof covering made of natural clay that is molded heated and dried into various shapes and profiles. 

Coal tar - a dark brown or black substance derived from the distillation of coal that is processed for use in various roofing and waterproofing applications. 

Coating asphalt - Specially blended asphalt applied to the top surface of composition shingles that acts as a primary weatherproofing component. 

Combustible - capable of burning 

Composition shingle - see asphalt shingle 

Concrete tile - a type of steep-slope roof covering made of concrete that is formed into various shapes and profiles. 

Coping - the covering piece on top of a wall exposed to the weather, usually made of metal, masonry, or stone and sloped to carry off water. 

Counter flashing - a formed metal or elastomeric sheeting secured on or into a wall curb, pipe, rooftop unit or other surface to cover and protect the upper edge of a base flashing and its associated fasteners. 

Dead load - permanent loads on a building that generally include the weight of the roof deck, roof system and equipment attached above or below the deck. 

Deck - the structural component of the roof of a building to which a roof system is installed. 

Dimensional shingle - see laminated shingle 

Direct nailing - attachment of a roof system component using nails driven directly through the material. 

Double lock standing seam - a metal roof panel seam that uses a double-overlapping interlock between two metal panels. 

Downspout - a vertical pipe or conduit used to carry runoff water from a scupper, conductor head or gutter of a building to a lower roof level or to the ground or storm water runoff system. 

Eave - the lower edge of a sloping roof that projects beyond the wall. 

Eave vent - an opening or device designed to allow the movement of air, heat or water vapor typically located at the underside of an eave. 

Elastomeric coating - a coating that is capable of being stretched at least twice its original length (100 percent elongations) and recovering to its original dimensions. 

Embedded edge metal - a metal accessory used to finish, seal or trim an exposed edge of a roof system. Emissivity - the ability of a roofing material to cool down, or release energy back into the atmosphere. Environmental protections agency (EPA) - the U.S. governmental agency responsible for administration laws to control and or reduce pollution of air, water and land.

EPDM roof membrane - a thermoset single-ply roof membrane made from a cured rubber material, ethylene propylene diene monomer 

Expansion joint - a structural separation between two building elements that allows free movement between the elements without damage to the roof or waterproofing system. 

Expansion joint cover - a flexible or semi-flexible cover used to weatherproof an expansion joint. 

Exposure - the amount of roofing material left exposed to the weather after steep-slope roof system installation is complete. 

Field - the open part of a roof. 

Fire retardants - chemicals that are impregnated, under pressure, into roofing materials that reduce fire hazards. 

Flammable - subject to easy ignition and rapid flaming combustion. 

Flashing - components used to weatherproof or seal roof system edges at perimeters, penetrations, drains and other places where a roof covering is interrupted or terminated or where a roof covering transitions between roof systems. 

Green roof - an area of plantings/landscaping installed above a waterproofed base on a roof. 

Gutters - a channeled component installed along the down slope perimeter of a roof to convey runoff water from the roof to the drain leaders or downspouts. 

Head lap - the distance of overlap measured from the uppermost ply or course to the point where it laps over the undermost ply or course. 

Hoist - a mechanical lifting device. 

Hybrid roof membrane - a combination of built-up roof plies and a polymer-modified bitumen roof membrane. 

Insulation - a material designed to reduce the flow of heat, either from or into a building. 

Integral standing seam - a metal roof panel seam that has interlocking seaming components preformed into its profile 

Laminated shingle - asphalt shingle that provides a dimensional appearance by lamination two or more layers of material. Also called architectural shingle or dimensional shingle 

Life-cycle cost - the total cost to purchase and maintain a roof system over its entire life divided by the total number of years in service. 

Live loads - temporary loads on a building that generally include the weight of people, construction equipment, rain, ice and snow

Low-slope roof - a category of roofs-generally weatherproof membranes-installed on slopes at or less than 3:12 

Lugs - small protruding legs molded into the underside of some concrete roofing tiles. 

Mechanical vent - a device with moving or mechanical parts designed to force the movement of air, heat or water vapor. 

Mechanically attached - a general description for roof system components when they are attached to a substrate at defined intervals using nails, screws or other type of fastening device 

Membrane - a flexible or semi-flexible roof covering whose primary function is to exclude water. 

Metal roof panel - an interlocking metal sheet having a minimum installed weather exposure of 3 square feet 

Metal roof shingle - an interlocking metal sheet having an installed weather exposure of less than 3 square feet 

Modified bitumen membrane - see polymer-modified bitumen membrane 

Nail stripper - a metal container used to hold and pre-align nails. 

Nail able roof deck - a roof deck with the ability to have roofing fasteners installed without pre-drilling holes 

National roofing contractors association (NRCA) - a national association of roofing, roof deck, sheet metal and waterproofing contractors and other industry-related stakeholders 

Non-nail able roof deck - a roof deck that requires pre-drilled holes to install roofing fasteners 

Occupational safety and health administration - commonly known as OSHA. A federal or state agency under the U.S. Department of Labor that publishes and enforces safety and health regulations for most businesses and industries in the U.S 

Oil canning - physical distortions in the flatness of metal that only affect appearance. 

On-center spacing - consistent spacing measure from the center of one item or object to the next; commonly used to describe fastener spacing. 

Parapet wall - the part of a perimeter wall that extends above a roof 

Personal fall arrest system - a system used to arrest an employee in a fall from a working level. It consists of an anchorage, connectors, and a body belt or body harness and may include a lanyard, deceleration device, lifeline, or suitable combinations of these. 

Personal protective equipment (PPE) - equipment used or clothing worn by a roofing worker that is capable of preventing injury to or impairment in the function of any part of the body through absorption inhalation or physical contact

Photovoltaic - the process of converting light into electricity; capable of producing electricity from light. 

Pneumatic tools - tools powered by compressed air 

Polymer - modified bitumen membrane - roofing sheets made of chemically modified asphalt or coal tar and reinforcement that sometimes are surfaced. 

Polyurethane - various resins, widely varying in flexibility, used in chemical-resistant coating, adhesives and foams. 

Polyvinyl chloride (PVC) roof membrane - a thermoplastics single-ply roof membrane made from flexible polyvinyl chloride material 

Ponding - the excessive accumulation of water at low-lying areas on a roof that remains more than 48 hours after the end rainfall under conditions conducive to drying 

Positive drainage - the condition in which a roof assembly is designed to ensure drainage of a roof area within 48 hours after the end rainfall during conditions conducive to drying 

Preservative treatment - chemicals applied to roofing materials intended to slow their deterioration. 

Primer - a substance applied to one or both surfaces that improve the ability of two materials to bond. 

Re-cover - the addition of a new roof membrane or steep-slope roof covering over a major portion of an existing roof assembly. This process does not involve removing the existing roofing material 

Reflectivity - the ability to bounce the sun's energy back into the atmosphere instead of allowing it to be absorbed into a building 

Reinforcement - materials such as woven or nonwoven fiberglass or polyester mats or scrims used m a roof membrane to provide additional physical properties 

Replacement - the practice of removing an existing roof system down to the roof deck and replacing it with a new roof system 

Reroofing - the process of re-covering or tearing-off and replacing an existing roof system 

Retrofit - constructing a steep-slope roof over an existing low-slope roof 

Ridge - the highest point on a roof represented by a horizontal line running the length of the area where two sloping roof areas intersect 

Ridge cap - a material or covering applied over the ridge of a roof system 

Ridge vent - an opening or device designed to allow the movement of air, heat or water vapor located at Rise-the height of a roof area from its lowest to highest point, or the vertical dimension of a roofs slope Roof- the cover of a building (noun) or to cover with a roof (verb) 

Roof assembly - an assembly of interacting roof components including a roof deck, vapor retarder (if present), insulation and roof covering 

Roof asset management - a proactive approach to roof system maintenance that generally maximizes its life and reduces annual life-cycle cost 

Roof hatch - a door mounted over an opening in a roof deck used for access to the roof or deck 

Roof system - a system of interacting components, generally consisting of a membrane or primary roof covering and roof insulation (not including the roof deck) 

Run - the length of a roof area from its lowest to highest point, or the horizontal dimension of a roof s slope 

Safety regulations - regulations employers are required to comply with that are established as law by the Occupational Safety and Health Administration (OSHA) 

Sealant - a material that has the adhesive and cohesive properties to form a seal 

Shingle - a small unit of prepared roofing material designed for installation in overlapping rows (or courses) on inclines normally exceeding 3:12 slope (noun) or to cover with shingles (verb) 

Side lap - the continuous longitudinal overlap of neighboring like materials 

Single-lock standing seam - a metal roof panel seam that uses one overlapping interlock between two metal panels 

Single-ply roof membrane - a roof membrane in which the principal roof covering is a shingle-layer flexible membrane 

Single-ply roof system - a roof system in which the principal roof covering is a single layer, flexible, thermoset or thermoplastic membrane 

Slate - a type of steep-slope roof covering that is cut and split out of natural rock mined from the earth Slope - the angle of incline, usually expressed as a ration of rise to run 

Snap-lock standing seam - a metal roof panel seam that uses a separate cap that snaps over the standing 

Spray polyurethane foam (SPF) - a spray-applied foamed plastic material that forms rigid, adhered, water-resistant and insulating membrane 

Standing seam - in metal roofing, a seam made by turning up the edges of two adjacent metal panels and then joining them in a variety of ways 

Static vent - an opening or device without moving parts designed to allow the movement of air. heat or water vapor 

Steel free and mallet - hand tools used to split wood logs for production of wood shakes

Steep-slope roof - a category of roofing-generally water shedding covering installed on slopes greater than 3:12 

Stripping sheet - membrane flashing strips used for sealing or flashing metal flashing flanges into a roof membrane 

Structural deck - a component of the roof of a building that must be capable of safely supporting the dead and live loads 

Structural metal panel roof system - a weatherproof roof system composed of metal panels usually applied over open framing rather than a continuous or closely spaced roof deck 

Structural panel - a metal roof panel designed to be applied over open framing rather than a continuous or closely spaced roof deck 

Substrate - the surface upon which roofing materials are applied 

Surfacing - the top layer or layers of a roof covering designed to protect the underlying roofing material from direct exposure to the weather 

Sustainable building - a building that provided the specified building performance requirements while minimizing disturbance to add improving the functioning of local, regional and global ecosystems during and after construction and specified service life 

Synthetics - man-made materials; or man-made steep-slope roof covering materials that look similar to natural materials 

System layout - the positioning, progression and direction roof system membranes or covering are installed 

Tab - the exposed portion of three-tab asphalt shingles defined by tab cutouts 

Tab cutout - the space between tabs of a three-tab asphalt shingle 

Tapered insulation - an insulation material that becomes gradually thinner or narrower at one end. Often used to provide positive drainage or a gradual transition from one layer of insulation to another Tear-off-the removal of all roof system components down to the structural deck 

Termination - a treatment or method of anchoring and or sealing the free edges of the membrane in a roof or waterproofing system 

Termination bar - a metal or plastic bar used to anchor the free edges of the membrane in a roof or waterproofing system 

Thermoplastic - a material that softens when heated and hardens when cooled. This process can be repeated provided the material is not heated above the point where decomposition occurs

Thermoplastic olefin CTPO) roof membrane - a thermoplastic single-ply roof membrane made from flexible thermoplastic olefin materials 

Thermoset - having the property of being substantially permanently hard and rigid after being cured 

Three-tab asphalt shingle - a common asphalt shingle that resembles three individual pieces of roofing after applied 

Through-wall scupper drain - a drainage device in the form of an outlet through a wall or parapet wall with a soldered sheet metal sleeve 

Underlayment - a sheet material installed between a roof deck and roof covering, usually used in a steep-slope roof construction, that is primarily used to separate the roof covering from the roof deck and provide secondary weather protection for the roof area of a building. 

Ultraviolet degradation - deterioration caused by exposure to ultraviolet light 

Valley - the internal angle formed by the intersection of two sloping roof planes 

Vapor retarder - a layer or layers of material used to appreciably reduce the flow or water vapor into a roof assembly 

Warranty - a guarantee given to the purchaser by a company stating that a product is reliable and free from known defects. 

Water-shedding - the ability of individual, overlapping components to resist the passage of water that is moving 

Waterproof - the quality of a material or component to prevent water entry 

Weatherproof - the ability of a membrane or roof covering to prevent the passage of water with a limited amount of pressure exerted from water at rest

Wood shake - a rough textured piece of split wood designed for installation in overlapping rows (or courses) on inclines normally exceeding 4:12 slope

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Wood shingle - a smooth piece of sawn wood designed for installation in overlapping rows (or courses) on inclines normally exceeding 4:12