Roofing Definitions and Terms
ASTM – American Society for Testing and Materials. A voluntary organization concerned with the development of consensus standards, testing procedures and specifications.
Asphalt – A bituminous waterproofing agent applied to roofing materials during manufacturing.
Asphalt Roofing Cement – An asphalt-based cement used to bond roofing materials. Also known as flashing cement or mastic; should conform to ASTM D4586.
Back Surfacing – Fine mineral matter applied to the back side of shingles to keep them from sticking.
Balanced System – A ventilation system where 50% of the required ventilating area is provided by vents located in the upper portion of the roof with the balance provided by undereave or soffit vents.
Built-Up Roof – A flat or low-slope roof consisting of multiple layers of asphalt and ply sheets.
Bundle – A package of shingles. There are 3, 4 or 5 bundles per square.
Butt Edge – The lower edge of the shingle tabs.
Caulk – To fill a joint with mastic or asphalt cement to help prevent leaks.
Chalk Line – A line made on the roof by snapping a taut string or cord dusted with chalk. Used for alignment purposes.
Class “A” – The highest fire-resistance rating for roofing as per ASTM E108. Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.
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 two inches from the valley centerline. The valley flashing is not exposed.
Concealed Nail Method – Application of roll roofing in which all nails are driven into the underlying course of roofing and covered by a cemented, overlapping course. Nails are not
exposed to the weather.
Counter Flashing – That portion of the flashing attached to a vertical surface to help 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 help 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. It is the structural base for the roof, usually made of wood or plywood.
Dormer – A structure containing a window that projects vertically through the sloping plane of a roof.
Double Coverage – Application of asphalt roofing such that the 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. Also called a leader.
Drip Edge – A noncorrosive, nonstaining material used along the eaves and rakes to allow water runoff to drip clear of underlying contraction.
Eave – The horizontal, lowest edge of a sloped roof that extends beyond the exterior wall.
Eaves Flashing – Additional layer of roofing material applied at the eaves to help prevent damage from water backup.
Exposure – The part of each shingle that is exposed to the weather.
Exposure I Grade Plywood – Type of plywood approved by the American Plywood Association for exterior use.
Felt – Fibrous material saturated with asphalt and used as an underlayment or sheathing paper.
Fiberglass Mat – An asphalt
Flashing – Pieces of metal or roll roofing 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 a minimum 26-gauge. Flashing Cement – See asphalt roofing cement.
Gable –The triangular upper portion of a sidewall that comes to a triangular point at the ridge of a sloping roof.
Gable Roof – A type of roof containing a sloping plane on each side of a single ridge with a gable at each end.
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. Features a gable at each end.
Granules – 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.
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.
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 of the same pitch on each of four sides. Contains no gables.
Hip Shingles – Shingles used to cover the inclined external angle formed by the intersection of two sloping roof planes.
Interlocking Shingles – Individual shingles that mechanically fasten to each other to provide wind resistance.
Laminated Shingles – Strip shingles containing more than one layer of tabs to create extra thickness. Also called dimensional or architectural shingles.
Lap – To cover the surface of one shingle or roll with another.
Low Slope Application – Method of installing asphalt shingles on roof slopes between two and four inches per foot.
Louver – A slanted opening for ventilation.
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. Includes no gables.
Mastic – See asphalt plastic roofing cement.
Metal Drip Edge – A narrow strip of noncorrosive metal used at the rake to facilitate water runoff.
Mineral-Surfaced Roofing – Asphalt shingles and roll roofing that are covered with granules.
Natural Ventilation – A ventilation system utilizing ventilators installed in openings in the attic and properly positioned to take advantage of natural air flow to draw hot summer or moist winter air out and replace it with fresh outside air.
Normal-Slope Application – Method of installing asphalt shingles on roof slopes between 4 inches and 21 inches per foot.
Off-Ridge Exhaust Vent – Individual exhaust vents usually located on the upper half of the roof that allow warm, humid air to escape from the attic. May be round, square or resemble a pipe or stack.
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.
Pitch – The degree of roof incline expressed as the ratio of the ridge, in feet, to the span, in feet.
Ply – The number of layers of roofing (one-ply, two-ply).
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 from the eave to the ridge.
Release Tape – A plastic or paper 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 Shingles – Shingles used to cover the horizontal external angle formed by the intersection of two sloping roof planes.
Ridge Vent – An exhaust vent that runs horizontally along the peak of the roof allowing warm, humid air to escape from the attic.
Rise – The vertical distance from the eaves line to the ridge.
Roll Roofing – Asphalt roofing products manufactured in roll form.
Roofing Cement – A compound used to seal flashings, seal down shingles and for other small waterproofing jobs. Where cement is required for sealing down shingles, use a dab about the size of a quarter unless otherwise specified.
Run – The horizontal distance from the eaves to a point directly under the ridge. One half the span.
Saturant – Asphalt used to impregnate an organic felt base material.
Saturated Felt – An asphalt-impregnated felt used as an underlayment between the deck and the roofing material.
Self-Sealing Cement – A thermal-sealing tab cement built into the shingle to firmly cement the shingles together automatically after they have been applied properly and exposed to warm sun temperatures. In warm seasons, the seal will be complete in a matter of days. In colder seasons, sealing time depends on the temperature and amount of direct sunlight hitting the shingles. Hand sealing with cement should be done to ensure sealing in winter.
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 head of the sun after application.
Selvage – That portion of roll roofing overlapped by the succeeding course to obtain double coverage.
Shading – Slight differences in shingle color that may occur as a result of normal manufacturing operations.
Sheathing – Exterior-grade boards used as a roof deck material.
Shed Roof – A roof containing only one sloping plane. Has no hips, ridges, valleys or gables.
Slope – The degree of incline expressed as the ratio of the rise, in inches, to the run, in feet.
Soffit – The finished underside of the eaves.
Span – The horizontal distance from eaves to eaves.
Specialty Eaves Flashing Membrane – A self-adhering, waterproofing shingle underlayment design to protect against water infiltration due to ice dams or wind-driven rain.
Square – A unit of roof measure covering 100 square feet.
Starter Strip – Asphalt roofing applied at the eaves that provides protection by filling in the spaces under the cutouts and joints of the first course of shingles.
Tab – The exposed portion of strip shingles defined by cutouts.
Three-Tab Shingles – Strip shingles containing three exposed tabs that are evenly spaced across the width of each shingle.
Top Lap – That portion of the roofing covered by the succeeding course after installation.
UL Label – Label displayed on packaging to indicate the listing for fire and/or wind resistance of asphalt roofing.
Undereave Vent – Intake vents located under the eaves of the roof that help draw cool dry air into the attic.
Underlayment – A layer of asphalt-saturated felt (sometimes referred to as tar paper) which is laid down on a bare deck before shingles are installed to provide an additional protection for the deck.
Valley – The internal angle formed by the intersection of two sloping roof planes to provide water runoff.
Vapor Retarder – Any material used to prevent the passage of water vapor. Material which, when installed on the high-vapor-pressure (warm in winter) side of a material, retards the passage of moisture vapor to the lower-pressure (cold in winter) side. Note exception: Florida and Gulf Cost – Check local building codes to determine on which side the vapor retarder should be placed.
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.
Ventilators – Devices that eject stale air and circulate fresh air (ridge, roof, gable, undereave, foundation or rafter vents and vented soffit panels)
Water Barrier – A self-adhesive waterproofing membrane used along eaves and valleys to protect these sensitive areas against wind-driven rain.
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.