1. Decking or sheathing: The structural material such as plywood, boards, planks or other structural sheathings over which roofing is installed.
2. Dormer: A small, raised roof area, usually with a vertical window that projects from a sloping roof and usually illuminates a bedroom.
3. Drip edge: A trim metal piece is installed at the roof's edge to keep shingles off the deck, extending them out over eaves and gutters.
4. Eave: The edge of a roof that overhangs the perimeter wall.
5. Fascia: The trim around the perimeter of a building, just under the roofing. Wood is most common in residential construction.
6. Flashing: Material installed around a roof penetration or along an edge to help keep moisture from entering the layers below.
7. Roof ridge vent: A gap in the wood deck at the highest point of the roof to allow air flow from the inside to the outside of the attic through a prefabricated air exhaust vent.
8. Roofing felt or underlayment: Typically made of asphalt-saturated paper or synthetic materials and installed on top of the roof deck to protect the structure beneath the roof system.
9. Soffit: The underside exposed area of a roof eave or overhang.
10. Starter strip: The first row of shingle roofing that is installed at the edge of the eave of the structure.
11. Valley: Where two downward-sloping roof sections join, creating a "V" shaped channel for diverting water.
12. Penetration: Any constructed item going through the roofing system that requires flashing.
1. Decking or sheathing: The structural material such as plywood, boards, planks or other structural sheathings over which roofing is installed.
2. Dormer: A small, raised roof area, usually with a vertical window that projects from a sloping roof and usually illuminates a bedroom.
3. Drip edge: A trim metal piece is installed at the roof's edge to keep shingles off the deck, extending them out over eaves and gutters.
4. Eave: The edge of a roof that overhangs the perimeter wall.
5. Fascia: The trim around the perimeter of a building, just under the roofing. Wood is most common in residential construction.
6. Flashing: Material installed around a roof penetration or along an edge to help keep moisture from entering the layers below.
7. Roof ridge vent: A gap in the wood deck at the highest point of the roof to allow air flow from the inside to the outside of the attic through a prefabricated air exhaust vent.
8. Roofing felt or underlayment: Typically made of asphalt-saturated paper or synthetic materials and installed on top of the roof deck to protect the structure beneath the roof system.
9. Soffit: The underside exposed area of a roof eave or overhang.
10. Starter strip: The first row of shingle roofing that is installed at the edge of the eave of the structure.
11. Valley: Where two downward-sloping roof sections join, creating a "V" shaped channel for diverting water.
12. Penetration: Any constructed item going through the roofing system that requires flashing.
Here are some common flat roofing (low slope) and residential roofing (steep slope) terms that homeowners, building owners and property managers should know.
When you are trying to understand your roof maintenance needs and the solutions to your roof problems, it is very helpful to have a base of roofing information to refer back to. Here at AskARoofer we have collated some common terms used in the steep- and low-slope roofing industry to help you learn!
To get a generalized understanding, check out these videos from John Kenney, one of AskARoofer’s resident experts and the president of Cotney Consulting Group.
In addition to these basics, we have collected some of the common terms that are used when talking about roofs. This is a great list to reference as you talk with roofing contractors when you have roof problems or need roof maintenance.
Acrylic coating: These are water-based, flexible protective layers applied to roofing surfaces to extend their lifespan, improve reflectivity, and enhance waterproofing. They can be painted on the surface and are known for their ease of application, UV resistance, and ability to accommodate roof movements without cracking.
Architectural shingles: An asphalt shingle made up of multiple layers, also known as dimensional or laminated shingles.
Asphalt: A bituminous waterproofing material applied to roofing materials during manufacture.
Asphalt primer: A thin liquid bitumen applied to a surface to improve the adhesion of self-adhering membranes and to absorb dust.
Asphalt roof cement: An asphalt-based cement used to bond roofing materials. Also known as flashing cement or mastic.
ASTM International: A voluntary organization concerned with development of consensus standards, testing procedures and specifications.
Ballast: A material installed over a roof membrane to help protect or hold it in place. Ballasts can consist of aggregate or concrete pavers.
Base flashing: That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering.
Base sheet: A product intended to be used as a base ply in a self-adhering roll roofing system.
Base-ply sheet: A product intended to be the base or middle ply in a residential self-adhering roll roofing system.
Built-up roof (BUR): A flat or low-sloped roof consisting of multiple layers of ply sheets embedded in hot asphalt.
Bundle: A package of shingles. There are typically 3, 4 or 5 bundles per square.
Butt edge: The lower edge of the shingle tabs.
Cap sheet: A mineral surfaced material that is used by itself or as the top layer of multi-layer rolled roof covering system.
Class 1 impact resistance: Shingles that are designed to be more resistant to impacts resulting from hailstorms. Impact resistant shingles are typically tested and classified in accordance with UL 2218. This classification means that the material didn’t break when hit twice in the same spot with a 1.25-inch steel ball or ice ball.
Class 2 impact resistance: Shingles that are designed to be more resistant to impacts resulting from hailstorms. Impact resistant shingles are typically tested and classified in accordance with UL 2218. This classification means that the material didn’t break when hit twice in the same spot with a 1.5-inch steel ball or ice ball.
Class 3 impact resistance: Shingles that are designed to be more resistant to impacts resulting from hailstorms. Impact resistant shingles are typically tested and classified in accordance with UL 2218. This classification means that the material didn’t break when hit twice in the same spot with a 1.75-inch steel ball or ice ball
Class 4 impact resistance: Shingles that are designed to be more resistant to impacts resulting from hailstorms. Impact resistant shingles are typically tested and classified in accordance with UL 2218. This classification means that the material didn’t break when hit twice in the same spot with a 2-inch steel ball or ice ball.
Class “A” fire resistance: The highest fire test classification for roofing as per ASTM E108 or UL790. Indicates whether roofing is able to withstand severe exposure to fire originating from sources outside the building. This is considered severe fire test exposure.
Class “B” fire resistance: The second highest fire test classification for roofing as per ASTM E108 or UL790. Indicates whether roofing is able to withstand severe exposure to fire originating from sources outside the building. It is considered moderate fire test exposure.
Class “C” fire resistance: The lowest fire test classification for roofing as per ASTM E108 or UL790. Indicates whether roofing is able to withstand severe exposure to fire originating from sources outside the building. It is considered light fire test exposure.
Collar: Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening. Also called a vent sleeve.
Coping: Fabricated commonly from metal and used to cover the top of a wall to protect it from the elements.
Counter flashing: That portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing.
Course: A row of shingles or roll roofing running the length of the roof.
Cricket: A peaked saddle construction at the back of a chimney to prevent accumulation of snow and ice and to deflect water around the chimney.
Deck: The surface, installed over the supporting framing members, to which the roofing is applied.
Decking or substrate or sheathing: The material that lays between the structural components of a roof (joists and trusses) that the insulation and the roofing system are installed over. Common material in commercial construction is steel, precast concrete panel, structural concrete, cementitious wood fiber, wood planking, plywood/OSB and poured gypsum.
Dormer: A framed window unit projecting through the sloping plane of a roof.
Downspout or leader: A pipe for draining water from roof gutters. Also called a leader.
Drip edge: A corrosion-resistant, non-staining material used along the eaves and rakes to allow water run-off to drip clear of underlying construction.
Eave: The horizontal, lower edge of a sloped roof.
EPDM: A synthetic rubber single-ply roofing membrane (ethylene propylene diene terpolymer) used in low-slope applications.
Fascia: The trim around the perimeter of a building, just under the roofing. Wood is most common in residential construction.
Fasteners: Any type of screw, rivet or nail used to secure insulation, base sheets, metal panels, trim and flashing materials together or to the roof deck.
Felt: Fibrous material saturated with asphalt and used as an underlayment or sheathing paper.
Fiberglass mat: The core material in an asphalt roofing shingle manufactured from glass fibers.
Fire ratings: Grade based on standard testing procedures of various materials. This indicates whether roofing is able to withstand severe exposure to fire originating from sources outside the building. There are three levels, Class A (highest), Class B (second highest) and Class C (lowest).
Flashing: Pieces of metal used to prevent seepage of water into a building around any intersection or projection in a roof such as vent pipes, chimneys, adjoining walls, dormers and valleys. They are found along the roof's perimeter or at penetrations, walls, expansion joints, valleys, drains and other vertical areas of a roofing system.
Fluid-applied: Also sometimes called liquid-applied. It’s an application of bituminous, polymer-modified bitumen or polymeric roof and waterproofing membranes, flashings, cements, adhesives or coatings installed at ambient or slightly elevated temperatures.
Fully adhered installation: When single-ply membrane is installed using adhesives that is typically a low-rise foam. A spray rig is used to mix part A and part B adhesive and spray it on the roof. Once proper tack is achieved the membrane can be rolled out onto the adhesive.
Gable: The upper triangular portion of a sidewall that comes to a point at the ridge of a double sloping roof.
Granules: Typically, ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.
Head lap: Shortest distance from the butt edge of an overlapping shingle to the upper edge of a shingle in the second course below. The triple coverage portion of the top lap of strip shingles.
Heat welding: How PVC and TPO membranes are attached together, the seams are heat welded typically using an automated welder, like a Leister.
Hip: The inclined external angle formed by the intersection of two sloping roof planes. Runs from the ridge to the eaves.
Hip roof: A type of roof containing sloping planes on each of four sides. Contains no gables.
Ice dam: Condition formed at the lower roof edge by the thawing and re-freezing of melted snow on the overhang. Can force ponded water up and under shingles, causing leaks.
Impact resistant shingles: Shingles that are designed to be more resistant to impacts resulting from hailstorms. Impact resistant shingles are typically tested and classified in accordance with UL 2218, and may be classified as Class 1 through Class 4, Class 4 is the most resilient.
Joist: Any of the small timbers, metal or wood beams arranged parallel to one another and spanning from wall to wall to support a floor, ceiling or roof of a building.
Kick out: A lower downspout section used to direct water away from a wall.
Kick-out flashing (diverter): A metal flashing detail installed at the eave end of a roof-to-wall transition designed to direct runoff away from the wall or wall cladding.
Laminated shingles: Shingles containing more than one layer to create extra thickness. Also called three-dimensional shingles or architectural shingles.
Lap: To cover the surface of one shingle or roll with another.
Lap cement: An asphalt-based cement (conforming to ASTM D3019) used to adhere overlapping plies of roll roofing.
Leader or downspout: A pipe for draining water from roof gutters. Also called a downspout.
Liquid membrane or roof membrane: A flexible or semiflexible roof covering or waterproofing whose primary function is to exclude water. This is multiple components (including liquid applied coatings and mesh membranes) that come together to form one, new roof.
Liquid-applied: Also sometimes called fluid-applied. It’s an application of bituminous, polymer-modified bitumen or polymeric roof and waterproofing membranes, flashings, cements, adhesives or coatings installed at ambient or slightly elevated temperatures.
Mastic: An asphalt-based cement used to bond roofing materials. Also called asphalt roof cement.
Mechanically attached installation: When single-ply membrane is installed using fasteners and plates. There are some systems that use thermal induction weld machines like OMG's Rhinobond to make the process faster and fasteners more secure.
Mineral-surfaced roofing: Asphalt shingles and roll roofing that are covered with granules.
Modified bitumen: This is a type of rolled roofing membrane manufactured with polymer-modified asphalt and polyester or fiberglass reinforcement. Meant for buildings with low-slope or flat roofs, combining traditional roofing materials with modern polymers for enhanced durability and flexibility.
Mopping: When a roofer applies hot asphalt or coal tar using a hand mop or mechanical applicator.
Nailer: (Sometimes referred to as "blocking"); a piece or pieces of dimensional lumber and/or plywood secured to a structural deck or walls that provides a receiving medium for the fasteners used to attach membrane or flashing.
Nailing strips: A member, usually of wood, set into or secured to nonnailable roof decks or walls to allow for positive anchorage by nailing of roofing felts, insulation or flashings.
Open valley: Method of valley construction in which shingles on both sides of the valley are trimmed along a chalk line snapped on each side of the valley. Shingles do not extend across the valley. Valley flashing is exposed.
Organic felt: An asphalt roofing base material manufactured from cellulose fibers.
Pipe collar: A circular collar that goes around a pipe to keep it from leaking.
Ply: The number of layers of roofing (i.e., one-ply, two-ply).
Polyisocyanurate insulation: Polyiso or iso for short. This is installed on the roof deck and under the roofing membrane. For extra protection a cover board sometimes is installed over the iso.
Ponding: The accumulation of water after rainfall at low-lying areas on a roof that remains wet when other parts of the roof have dried.
Portable rollforming machine: This machine bends metal into ridges or gutters or cuts metal to the dimensions needed for metal roofs.
Primer: Typically an acrylic- or silicone-based primer used to prepare surfaces for bonding with materials such as roof coatings and self-adhering asphalt sheets.
PVC (polyvinyl chloride): A single-ply roofing membrane made from a synthetic plastic polymer used in low-sloped roofing applications.
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Racking: Roofing application method in which shingle courses are applied vertically up the roof.
Rafter: The supporting framing member immediately beneath the deck, sloping from the ridge to the wall plate.
Rake: The inclined edge of a sloped roof over a wall.
Release tape: A plastic strip that is applied to the back of self-sealing shingles. This strip prevents the shingles from sticking together in the bundles and need not be removed for application.
Ridge: The uppermost, horizontal external angle formed by the intersection of two sloping roof planes.
Ridge cap shingles: Material specifically made to cover the peak ridge or hips of the roof.
Ridge vent: A ventilator located at the ridge that allows the escape of warm and/or moist air from the attic area or rafter cavity.
Roll roofing: Asphalt roofing products manufactured in roll form.
Roof coatings:: Fluid-applied roofing systems that are adhered to a substrate. These frequently used in the restoration of aging roofs. Most common are acrylic and silicone. These are not to be confused with membranes as its primary use is not waterproofing.
Roof membrane or liquid membrane: A flexible or semiflexible roof covering or waterproofing whose primary function is to exclude water. This is multiple components (including liquid applied coatings and mesh membranes) that come together to form one, new roof.
Roofing felt or underlayment: A material installed on top of the roof decking to protect the structure beneath the roof system and typically made of asphalt-saturated paper or synthetic materials.
Saturated felt: An asphalt-impregnated felt used as an underlayment between the deck and the roofing material.
SBS (styrene-butadiene-styrene): A synthetic polymer that is mixed with asphalt in some products to increase the flexibility and other attributes of the products.
Self-adhering shingle underlayment: A self-adhering waterproofing underlayment designed to protect against water infiltration due to ice dams or wind driven rain.
Self-sealing shingles: Shingles containing factory-applied strips or spots of self-sealing adhesive.
Self-sealing strip (or spot): Factory-applied adhesive that bonds shingle courses together when exposed to the heat of the sun after application.
Selvage: That portion of roll roofing overlapped by the succeeding course to obtain single or double coverage at the lap.
Sheathing or decking or substrate: The material that lays between the structural components of a roof (joists and trusses) that the insulation and the roofing system are installed over. Common material in commercial construction is steel, precast concrete panel, structural concrete, cementitious wood fiber, wood planking, plywood/OSB and poured gypsum.
Silicone coatings: These are highly durable, moisture-cured coatings used to protect and extend the life of roofing systems. They are applied a single layer that fills in a roof's seams, cracks, and blisters. Silicone coatings offer excellent weather resistance, UV stability, and waterproofing properties, making them ideal for roofs exposed to extreme conditions. They are also able to endure the natural expansion and contraction (thermal movement) that occurs in large roof structures.
Single-ply: Rolled roofing membrane that comes in various thicknesses (mils). Common ones are 45-mil, 60-mil, 90-mil. Can have a fleece back for added durability. Materials include EPDM (rubber roofing), TPO (thermoplastic polyolefin) and PVC (polyvinyl chloride).
Slope: The degree of roof incline expressed as the ratio of the rise, in inches, to the run, in inches. For example, roof slope of 4/12 has a 4 inch rise every 12 inches.
Soffit: The finished underside of the eaves.
SPF (sprayed polyurethane foam): A foamed plastic material, formed by mixing and spraying two components — isocyanate (“A-component”) and resin containing a polyol (“B-component”) to form a rigid, fully adhered, water-resistant, insulating membrane. This material is sprayed as a liquid in multiple layers to expand into a foam, creating a solid layer across an existing roof. The membrane is both seamless and insulating, making this a popular choice for excellent thermal insulation, waterproofing and durability. It also helps to reduce energy costs and extend the roof's lifespan.
Square: A unit of roof measure covering 100 square feet.
Starter strip: Asphalt roofing applied at the eave that provides protection by an additional layer of material under the cutouts and joints of the first course of shingles.
Step flashing: Base flashing application method used where a vertical surface meets a sloping roof plane.
Strip shingles: Asphalt shingles made from a single layer that are approximately three times as long as they are wide.
Substrate or sheathing or decking: The material that lays between the structural components of a roof (joists and trusses) that the insulation and the roofing system are installed over. Common material in commercial construction is steel, precast concrete panel, structural concrete, cementitious wood fiber, wood planking, plywood/OSB and poured gypsum.
Synthetic underlayment: An underlayment product that is typically manufactured using polypropylene and is used as an alternative to felt underlayment.
Tab: The exposed portion of strip shingles defined by cutouts.
Three-tab shingle: A single-layer asphalt shingle separated by cut-outs into three tabs.
TPO: A thermoplastic polyolefin single-ply roofing membrane used in low-slope applications.
UL: Underwriters Laboratories, LLC
UL label: Label displayed on packaging to indicate the level of fire and/or wind resistance of asphalt roofing.
Underlayment or roof felt: Asphalt saturated felt or specially engineered synthetic material used beneath roofing to provide additional protection for the deck. It is installed on top of the roof decking to protect the structure beneath the roof system.
Valley: The internal angle formed by the intersection of two sloping roof planes.
Vapor retarder: Any material used to prevent the passage of water vapor.
Vent: Any outlet for air that protrudes through the roof deck such as a pipe or stack. Any device installed on the roof, gable or soffit for the purpose of ventilating the underside of the roof deck.
Warranty: A legal document from the roofing manufacturer or contractor to cover any issues with your new roof. There are three main types: Standard manufacturer's warranty (covers the products you purchase), extended manufacturer's warranty (covers contractor workmanship and purchased products) and workmanship warranty (covers the contractor installation for 1-2 years).
Woven valley: Method of valley construction in which shingles from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied. The valley flashing is not exposed.
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