Terminology

Roofing Terminology

TKnowing common roofing terminology will enable you as a homeowner to make an informed decision about roofing materials that are good matches for your home’s style and the region in which you live.  It will also help you understand the contract with your roofing professional and the project updates.

Listed in alphabetical order:
A-C	D-F	G-N	O-Z

Asphalt: A waterproofing agent applied to roofing materials during manufacturing.

Asphalt plastic roofing cement: An asphalt-based sealant used to bond roofing materials. Also known as flashing cement, roof tar, bull or mastic.

Back surfacing: Granular material applied to the back side of shingles to keep them from sticking during delivery and storage.

Base flashing: That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof.

Built-up roof: Multiple layers of asphalt and ply sheets bonded together.

Butt edge: The bottom edge of the shingle tabs.

Caulk: To fill a joint to prevent leaks.

Closed valley: The valley flashing is covered by shingles.

Coating: A layer of viscous asphalt applied to the outer roof surface to protect the roof membrane.

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

Concealed nail method: Application of roll roofing in which all nails are covered by a cemented, overlapping course.

Counter flashing: That portion of the flashing attached to a vertical surface above the plane of the roof to prevent water from migrating behind the base flashing.

Course: Row of shingles that can run horizontally, diagonally or vertically.

Cricket: A peaked water diverter installed at the back of a chimney to prevent accumulation of snow and ice and to deflect water.

Deck: The top surface of which a roof system is applied, surface installed over the supporting framing members.

Double coverage: Asphalt roofing whose lapped portion is at least two inches wider than the exposed portion, resulting in two layers of roofing material over the deck.

Downspout: A pipe for draining water from roof gutters to drain. Also called a leader.

Drip edge: L-shaped flashing used along the eaves and rakes to allow water run-off into the gutters and to drip clear of underlying construction.

Eave: The part of the roof that overhangs or extends outward and is not directly over the exterior walls or the buildings interior.

Exposed nail method: Application of roll roofing where nails are driven into the overlapping course of roofing. Nails are exposed to the elements.

Fascia: A wood trim board used to hide the cut ends of the roof's rafters and sheathing.

Felt: Fibrous material used as an underlayment or sheathing paper, describes roll roofing materials.

Flashing: Pieces of metal or roll roofing used to form water seal around vent pipes, chimneys, adjoining walls, dormers and valleys.

Gable: The end of an exterior wall that comes to a triangular point at the ridge of a sloping roof.

Granules: Ceramic-coated and fired crushed rock that is applied as the top surface of asphalt roofing products.

Gutter: The trough that channels water from the eaves to the downspouts. Usually attached to the fascia. Head lap: An overlapping of shingles or roofing felt at their upper edge.

Hip: The fold or vertical ridge formed by the intersection of two sloping roof planes. Runs from the ridge to the eaves. 

Ice dam: Condition forming water back-up at the eave areas by the thawing and re-freezing of melted snow on the overhang. Can force water under shingles, causing leaks.

Interlocking shingles: Individual shingles that mechanically fasten to each other to provide wind resistance.

Laminated shingles: Strip shingles made of two separate pieces laminated together to create extra thickness. Also called three-dimensional and architectural shingles.

Lap: Surface where one shingle or roll overlaps with another during the application process.

Mansard roof: A design with a nearly vertical roof plane connected to a roof plane of less slope at its peak. Contains no gables.

Mineral stabilizers: Finely ground limestone, slate, traprock or other inert materials added to asphalt coatings for durability and increased resistance to fire and weathering.

Nesting: A method of reroofing, installing a second layer of new asphalt shingles, in which the top edge of the new shingle is butted against the bottom edge of the existing shingle tab.

Pitch: The degree of roof incline expressed as the ratio of the rise, in feet, to the span, in feet.  Low Slope :Roof pitches that are less than 30 degrees. Normal Slope - Roof pitches that are between 30 and 45 degrees. Steep Slope - Roof pitches that are more than 45 degrees.

Rafter: The supporting framing that makes up the roof structure; immediately beneath the deck; the roof sheathing is nailed to the rafters.

Rake: The inclined edge of a sloped roof over a wall from the eave to the ridge. They can be close or extended.

Ridge: The horizontal external angle formed by the intersection of two sloping sides of a roof at the highest point of the roof, hip or dormer.

Run: The horizontal distance between the eaves and a point directly under the ridge; or one half the span.

Selvage: That portion of roll roofing overlapped by the application of the roof covering to obtain double coverage.

Sheathing: Exterior grade boards used as a roof deck material.

Shed roof: A single roof plane with no hips, ridges, valleys or gables, not connected to any other roofs.

Slope: The degree of roof incline expressed as the ratio of the rise, in inches, to the run, in feet.

Smooth-surfaced roofing: Roll roofing that is covered with ground talc or mica instead of granules (coated).

Soffit: The finished underside of the eaves that extends from the fascia to the siding and hides the bottom of an overhang.

Soil stack: A vent pipe that penetrates the roof.

Span: The horizontal distance from eaves to eaves.

Specialty eaves flashing membrane: A self-adhering, waterproofing shingle underlayment designed to protect against water infiltration due to ice dams or wind driven rain.

Starter strip: Asphalt roofing applied at the eaves as the first course of shingles installed.

Tab: The weather exposed surface of strip shingles between the cutouts.

Telegraphing: Shingles installed over an uneven surface that show distortion. Truss - A combination of beams, bars and ties, usually in triangular units to form a framework for support in wide span roof construction.

UL label: Label displayed on packaging to indicate the level of fire and/or wind resistance of asphalt roofing. Underlayment: A layer of asphalt based rolled materials installed under main roofing material before shingles are installed to provide additional protection for the deck.

Valley: The internal angle formed by the intersection of two inclined roof surfaces to provide water runoff.

Vapor barrier/retarder: Any material that prevents the passage of water or water vapor through it. Vent: Any device installed on the roof as an outlet for air to ventilate the underside of the roof deck.

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