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  • Writer's pictureEleven Exterior Inc

Roofing Terminology

Updated: Jun 28, 2023

When working with your roofing contractor, you may hear them use industry-specific terms related to your roofing project. While you can certainly ask them to clarify anything unfamiliar for you, it can be helpful to have a handy reference guide.


These are terms and jargons commonly used in the roofing industry. It may be convenience to use them to express your needs.

Roof structures and their terminologies
Roofing terminology

Asphalt: A bituminous waterproofing material applied to roofing materials during manufacture.

Architectural Shingles: Laminated Shingles containing more than one layer to create extra thickness. Also called three-dimensional shingles.

Base Sheet: A product intended to be used as a base ply in a self-adhering roll roofing system.

Blisters: Bubbles that may appear on the surface of asphalt roofing after installation.

Built-Up Roof: 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.

Asphalt shingles terminology
Asphalt shingle

Cap Sheet: A mineral surfaced material that is used by itself or as the top layer of multi-layer rolled roof covering system.

Caulk: To fill a joint with mastic or asphalt cement to prevent leaks.

Chalk Line: A line made on the roof by snapping a taut string or cord dusted with chalk. Used for alignment purposes.

Closed Cut Valley: A method of valley treatment in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed 2” from the valley centerline. The valley flashing is not exposed.

Collar: Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening. Also called a vent sleeve and pipe flashing.

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.

Coverage: The number of layers of material between the exposed surface of the roofing and the deck; i.e., single coverage, double coverage, etc.

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. The minimum thickness of a wood deck is a 15/32” exterior grade plywood or 7/16” exterior grade OSB or as required by local building codes. Also known as sheathing.

Dormer: A framed window unit projecting through the sloping plane of a roof.

Downspout: 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. (See Figure B.)


Roof structure terminology
Roof structure

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.

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. Galvanized metal flashing should be minimum 26-gauge.

Gable: The upper triangular portion of a sidewall that comes to a point at the ridge of a double sloping roof. (See Figure B.)

Gambrel Roof: A type of roof containing two sloping planes of different pitch on each side of the ridge. The lower plane has a steeper slope than the upper. Contains a gable at each end.

Granules: Typically ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.

Gutter: The trough that channels water from the eaves to the downspouts.

Hip: The inclined external angle formed by the intersection of two sloping roof planes. Runs from the ridge to the eaves. (See Figure B.)

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.

Lap: To cover the surface of one shingle or roll with another.

Mansard Roof: A type of roof containing two sloping planes of different pitch on each of four sides. The lower plane has a much steeper pitch than the upper, often approaching vertical. (See Figure B.)

Mid-ply Sheet: See Base-ply sheet.

Mineral Stabilizers: Finely ground limestone, slate, trap rock or other inert materials added to asphalt in shingles for durability and increased resistance to fire and weathering.

Mineral-Surfaced Roofing: Asphalt shingles and roll roofing that are covered with granules.

Nesting: A method of reroofing with new asphalt shingles over old shingles in which the top edge of the new shingle is butted against the bottom edge of the existing shingle tab.

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.

Overhang: That portion of the roof structure that extends beyond the exterior walls of a building.

Pallets: Wooden platforms used for storing and shipping bundles of shingles.

Ply: A layer of roofing (i.e., one-ply, two-ply).

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.

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. (See Figure B.)

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.

Reroofing: The process of removing existing roof coverings and replacing with a new roofing system.

Ridge: The uppermost, horizontal external angle formed by the intersection of two sloping roof planes. (See Figure B.)

Rise: The vertical distance from the eaves line to the ridge.

Roofing Tape: An asphalt-saturated tape used with asphalt cements for flashing and patching asphalt roofing.

Run: The horizontal distance from the eaves to a point directly under the ridge. One half the span.

SBS: Styrene-Butadiene-Styrene, which is a synthetic polymer that is mixed with asphalt in some products to increase the flexibility and other attributes of the products.

Selvage: That portion of roll roofing overlapped by the succeeding course to obtain single or double coverage at the lap.

Shading: Slight differences in shingle color that may occur as a result of normal manufacturing operations.

Shed Roof: A roof containing only one sloping plane. Has no hips, ridges, valleys or gables.

Single Coverage: Asphalt roofing that provides one layer of roofing material over the deck.

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.

Soil Stack: A vent pipe that penetrates the roof.

Span: The horizontal distance from eave to eave.

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.

Tab: The exposed portion of strip shingles defined by cutouts. (See Figure A.)

Tear Off: To remove an existing roofing system down to the structural deck.

Telegraphing: A shingle distortion that may arise when a new roof is applied over an uneven surface.

Top Lap: That portion of the roofing covered by the succeeding course after installation. (See Figure A.)

UL: Underwriters Laboratories, LLC

Underlayment: Asphalt saturated felt or specially engineered synthetic material used beneath roofing to provide additional protection for the deck.

Valley: The internal angle formed by the intersection of two sloping roof planes. (See Figure B.)

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.

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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