Toronto, Ontario
Roofing Glossary

Roofing Glossary


Algae discoloration – A type of roof discoloration caused by algae. Commonly, but inaccurately, called fungus growth. Usually it is dark brown to black in color.

Algae Resistant Shingles – Shingles which are coated with copper granules on the weather side to prevent the formation of algae and the resultant discoloration.

Algicidal Treatment – A method of cleaning discolored shingles with a bleach mixture to lighten the discoloration caused by algae formation.

Asphalt – A bituminous waterproofing agent applied to roofing materials during manufacture.

Asphalt feltSee Underlayment.

Asphalt roofing cement – An asphalt-based cement, containing solvent, used to bond roofing materials. Also known as asphalt plastic cement, flashing cement, muck, bull or mastic.

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Back surfacing – Fine mineral matter applied to the back side of shingles, keeping them from sticking together when packaged in the bundles.

Base flashing – The portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering. See Step flashing.

Battens – Parallel strips of wood to which roof tiles are fastened.

Blisters – Raised areas or bubbles that may appear on the surface of asphalt roofing after installation.

Blow-off – A condition in which shingles flutter or flap up and down with the wind, tear, and finally blow off the roof entirely.

Buckling – The formation of wrinkles or furrows across a shingle or shingles.

Bundle – A package of shingles. There are typically three, four or five bundles per square.

Butt edge – The lower edge of the shingle tabs

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Cap flashing – The portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing.

Caulk – To fill a joint with mastic or asphalt roofing cement, or the material used to fill the joint.

Certificate of Compliance – A certificate indicating that shingles meet their appropriate standards.

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. Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.

Class “B” – Fire-resistance rating that indicates roofing materials are able to withstand moderate exposure to fire originating from sources outside the building. (Not currently available for any asphalt shingle.)

Class “C” – Fire-resistance rating that indicates roofing materials are able to withstand light 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 2″ from the valley center line. The valley flashing is not exposed.

Coating Asphalt – A layer of asphalt applied to the base reinforce- ment material into which granules or other surfacing is embedded.

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

Color variation – Slight differences in shingle appearance which may be due to variations in normal manufacturing color blends or the mixing of color blends during shingle application.

COM-PLY Panels
– Composite panels made of wood veneer on the face and back, with an inside core of compressed wood strands.

Condensation – The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.

Counter flashingSee Cap flashing.

Course – A horizontal 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.

Cutout – The open portions of a strip shingle between the tabs.

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Date Codes – Date of manufacture printed on bundles.

Deck – The surface, installed over the supporting framing members, to which the roofing is applied.

Deck/Sheathing – The surface, usually plywood or oriented strand board OSB, to which roofing materials are applied.

Diagonal method – Roofing application method in which shingles are applied diagonally up the roof.

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

Double coverage – Application of asphalt roofing such that the lapped portion is at least 2″ 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 corrosion-resistant, non-staining material used along the eaves and rakes to allow water run-off to drip clear of underlying construction.

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Eaves – The horizontal, lower edge of a sloped roof.

Eaves flashing – Additional layer of roofing material applied at the eaves to help prevent damage from water back-up.

Exposure – The portion of the roofing exposed to the weather after installation, usually expressed in inches.

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Fascia – A flat board, band or face located at a cornice’s outer edge.

Feathering strips – Tapered wood filler strips placed along the butts of old wood shingles to create a level surface when re-roofing over existing wood shingle roofs. Also called Horsefeathers.

Felt – Organic fiber mat impregnated with asphalt and used as an underlayment. See Underlayment. See Organic felt.

Fiber glass mat – A reinforcing material for asphalt roofing manufactured from glass fibers.

Fiber Glass Shingles – Asphalt shingles made with a fiber glass mat.

FillerSee Mineral stabilizers.

Fire Rating – The system for classifying the fire resistances of various materials.  Roofing materials are classified A,B, Or C.  See Class A, B or C above.

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.

Flashing cementSee Asphalt roofing cement.

FRT Plywood – Fire Retardant Treated plywood.

Fungus stainSee Algae discoloration.

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Gable – The 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 sloping planes of the same pitch on each side of the ridge. Contains 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. Contains 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.

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Head lap – it is the shortest distance from the butt edge of an overlapping shingle to the upper edge of the shingle two courses below it. It is the “triple coverage” portion of the strip shingle system (designed to be minimum 2″ in length).

Heavyweight Dimensional Shingles – Sometimes called architectural shingles, these shingles combine a rough dimensional look with attractive natural color blends.

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. Sometimes called “hip and ridge” shingles.

Homasote® Roofing Decking – High density wood fiber board.

HorsefeathersSee Feathering strips.

HUD Ventilation Standard – Minimum standard requires one square foot of net free ventilation area for every 150 square feet of attic floor space. However if half of the open ventilation area is in the upper portion of the roof and half is in the lower area, the standard changes to one square foot of net free ventilation for every 300 square feet of attic floor space.

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Ice dam – Condition formed by the thawing and refreezing of melted snow, especially at the lower roof edge on the roof overhang and in gutters. Can cause water to pond and flow up and under shingles, causing leaks.

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Laminated shingles – Strip shingles containing more than one layer of tabs to create extra thickness. Also called three-dimensional shingles or architectural shingles.

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

LeaderSee Downspout.

LOADMASTER® Nailable Double Board Assembly
Trademarked roof decking composed of a double layer of mineral board placed over a rigid insulation board (optional), and fastened to a steel deck.

Louvers – Slatted devices installed in a gable or soffit( the underside of eaves) to ventilate the space below a roof deck and to equalize air temperature and moisture.

Low Budget Shingles – A class of shingles that can cause problems. They might have coloring that does not match from bundle to bundle, shingle lengths out of spec, or weak fiber glass mats. Such defects often lead to roofing difficulties.

Low-slope application – Method of installing asphalt shingles on roof slopes between 2″ and 4″ per foot.

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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. Contains no gables.

MasticSee Asphalt roofing cement.

Mid-Weight Dimensional Shingles
– Shadow lines and color blends give these shingles a more interesting appearance than common three-tab shingles. Typical weight: 235-265 lbs./sq.

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

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Nesting – A method of re-roofing 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.

No-cutout shingles – Shingles consisting of a single, solid tab with no cutouts.

Non-veneer panel – Any wood-based panel that does not contain veneered layers, such as oriented strand board (OSB) or waferboard.

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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.

OSB – Non-veneer oriented strand board.

Overhang – The portion of the roof structure that extends beyond the exterior walls of a building.

Overlay Shingle – A one-piece base shingle to which overlay pads, consisting of an additional layer of asphalt and granules are applied in random patterns to simulate two-piece laminate shingles.

Oxalic Acid – A diluted water solution of oxalic acid is used to reduce rust stains.

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

Parapet – a low wall projecting from the edge of a platform, terrace, or roof.

Patterning – The formation of various geometric designs or patterns on the roof resulting from overlay- or laminated tab-type shingles applied incorrectly or from incorrect color blends.

Plastic cementSee Asphalt roofing cement.

Penetrations – Vents, Pipes, stacks, chimneys, anything that penetrates a roof deck.

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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 normally should 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. Sometimes called “hip and ridge” shingles.

Ripper – Basic tool for tearing off old shingles. Also called the ripping shovel, it is a long handle connected at a steep angle to a flat blade with a serrated leading edge.

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

Roll roofing – Asphalt roofing products manufactured in roll form.

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

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Saturated felt – An asphalt-impregnated felt used as an underlayment between the deck and the roofing material.

Scuffing – Damage to the shingle surface, usually the granules or top coating layer, caused by foot traffic or by placing objects on newly installed shingles.

Sealant Adhesive – Applied to the face or back of shingles to hold them down in severe wind conditions.

Self-sealing shingles – Shingles containing factory-applied strips of self-sealing adhesive.

Self-sealing strip – Factory-applied adhesive that bonds shingle courses together when exposed to the heat of the sun after application.

Shading – Slight differences in shingle color that may occur as a result of normal manufacturing operations. See Color variation. See Patterning.

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.

Shoe-Wraps – Wrappings for workers shoes that prevent scuffing of shingles.

Sight Card – Cardboard geometrical shape used to determine roof slope from the ground.

Single coverage – Asphalt roofing that provides one layer of roofing material over the deck.

Sit-Upons – Carpet or foam rubber pieces that roofers kneel or sit on while working to avoid scuffing shingles in hot weather.

Slope – The degree of roof incline expressed as the ratio of the rise, in inches, to the run, in inches (or feet). Sometimes expressed as “pitch” in degrees of an angle.

Soffit – The finished underside of eaves.

Soffit Vents – Vents located under the eaves provide air intake. They should be used together with other higher elevation vents.

Soil stack – A vent pipe that penetrates the roof.

Square – A unit of roof measurement equaling 100 square feet of roof area or 10 feet by 10 feet.

Square tab shingles – Shingles on which tabs are all the same size and exposure.

Stabilized Asphalt Coating – A tough asphalt material used to coat the impregnated felt of the asphalt shingle. Also used as the only waterproofing in a fiberglass shingle. See also: Saturant.

Standard-slope application – Method of installing asphalt shingles on roof slopes between 4″ and 21″ per foot.

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. It also provides for sealing down of tabs of the first course of self-sealing shingles.

Steep-slope application – Method of installing asphalt shingles on roof slopes greater than 21″ per foot.

Step flashing – Base flashing application method used where a vertical surface meets a sloping roof plane. Utilizes multiple pieces of flashing material.

Stickering – The process of inserting spacers between deck panels before installation in order to allow them to reach a more natural moisture content and dimension.

Strip shingles – Asphalt shingles that are approximately three times as long as they are wide.

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Tab – The exposed portion of strip shingles defined by cutouts.

Tab cement – An asphalt-based cement used to adhere tabs of strip shingles to the course below. A type of asphalt roofing cement often supplied in tubes.

Tear Resistance – The industry-accepted method for comparing shingle toughness.

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

Truss – Engineered components that supplement rafters in many newer homes and buildings.  Trusses are designed for specific applications and cannot be altered or cut.

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UL – Underwriters Laboratories, Inc.

UL label – Label displayed on packaging to indicate the level of fire and/or wind resistance of asphalt roofing, and whether shingles meet certain Industry Roofing standards.

Underlayment – Asphalt-impregnated felt used beneath roofing to provide additional protection for the deck.

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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 – 1) Any outlet for air that protrudes through the roof deck, such as a pipe or stack. 2) Any device installed on the roof, gable or soffit for the purpose of ventilating the underside of the roof deck.

Vent sleeve See Collar.

Vent-Top Thermocal® – This is a nail base roof insulation with 3/16″ venting air space and an APA-rated 7/16″ OSB sheathing

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Waterproofing shingle underlayment – A special self-adhering waterproofing shingle underlayment designed to protect against water infiltration due to ice dams or wind-driven rain.

WB – Non-veneer wafer board.

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.

Roofing Glossary

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