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Glossary Of Terms

Welcome to the comprehensive Roofing Glossary and Terms page, brought to you by Wisconsin’s premier roofing contractor, Rosenow Customs. As a leader in the roofing industry, we understand the importance of clear communication and shared understanding when it comes to roofing projects. Whether you’re a homeowner, building manager, architect, or roofing professional, navigating the complex world of roofing terminology can be challenging. That’s why we’ve compiled this extensive guide to help bridge the gap and ensure everyone is on the same page.

In this glossary, you’ll find a wide range of roofing terms, covering everything from basic roofing components and materials to advanced installation techniques and potential issues. We’ve organized the terms alphabetically for easy reference, so you can quickly find the information you need. Whether you’re discussing a project with our team at Rosenow Customs or simply looking to expand your roofing knowledge, this glossary will serve as a valuable resource. So, let’s dive in and explore the language of roofing!


Accelerated weathering: the exposure of a specimen to a specified test environment for a specified time with the intent of producing effects similar to actual weathering in a shorter time period.

Adhere: The clinging of one surface to another either molecularly or otherwise.

Algae Discoloration: A type of roof discoloration caused by algae growth. Commonly described incorrectly as fungus growth.

Alligatoring: the cracking of the surfacing bitumen on a built-up roof or coating on an SPF roof, producing a pattern of cracks similar to an alligator’s hide.

Angled fasteners: Roofing nails and staples driven into decks at angles not parallel to the deck.

Apron flashing: a flashing located at the juncture of the top of a sloped roof and a vertical wall, chimney or steeper-sloped roof.

Architectural Shingle: A shingle that provides a dimensional appearance. See also Dimensional Shingle.

Area Divider: A flashed assembly usually extending above the roof surface that is anchored to the roof deck to relieve thermal stresses where an expansion joint is not required, or to separate large roof areas.

ARMA: The Asphalt Roofing Manufacturers Association, a trade association for North American manufacturers of asphalt roofing.

Asphalt: A substance left as a residue after processing crude oil. Asphalt is refined into various roofing grade specifications.

Asphalt Emulsion: A mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.

Asphalt Primer: See Primer.

Asphalt Roof Cement: Asbestos-free asphalt roof cement consisting of solvent-based bitumen, mineral stabilizers, and fibers. Conforms to ASTM D 2822 or D 4586.

Attic: the cavity or open space between the ceiling and the roof deck of a steep-sloped roof.


Back-nailing: the practice of blind nailing the back portion of roofing plies or other components in a manner so that fasteners are covered by the next ply and not exposed to weather.]

Back-Surfacing: A fine mineral material on the back side of roofing materials to keep them from sticking together while packaged.

Ballast: material such as aggregate or pavers which uses its mass to hold single-ply roof membranes in place.

Base flashing: plies or strips of roof membrane material used to seal the roof at horizontal-to-vertical intersections like roof-to-wall. Covers the edge of the field membrane.

Base sheet: an asphalt-impregnated felt placed as the first ply in some low-slope roof systems.

Bird Screen: Wire mesh installed over openings to prevent birds from entering a building or roof cavity.

Bitumen: a generic term for asphalt or coal tar, the waterproofing components in built-up roofing.

Blind-nailing: the use of nails that are not exposed to the weather in the finished roofing system.

Blister: an enclosed pocket of air trapped between impermeable layers of felt or membrane.

Blow-offs: When shingles are subjected to high winds and forced off the roof deck.

Bridging: When the roof membrane is unsupported at a juncture.

Built-Up Roof Membrane: A roof membrane consisting of layers of bitumen which serves as the waterproofing, with plies of reinforcement fabric between each layer.

Bundle: An individual package of shingles. There are typically 3-5 bundles per roofing square.


Cant strip: a beveled strip used under flashings to modify the angle where the roof meets a vertical element.

Cap sheet: an asphalt-impregnated felt used as the top ply of some built-up and modified bitumen roof systems.

Caulk: an elastic compound used to fill and seal joints or junctures 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 valley installation method where shingles from one side of the valley extend across while shingles from the other side are trimmed back 2″ from the valley center.

Coal Tar Pitch: A type of coal tar bitumen used in dead-level or low-slope built-up roofs, not for use on slopes exceeding 1/4″ per foot.

Collar: A 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 where all nails are driven into the underlying course and covered by overlap, not exposed to weather.

Condensation: The conversion of water vapor to liquid when warm air comes in contact with a cold surface.

Copper: A reddish-brown conductive metal sometimes used for metal roofing and flashing. Weathers to a greenish patina over time.

Counter Flashing: The metal or fabric flashing installed into walls or chimneys to cover and protect the top edges of base flashings and prevent moisture entry.

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 or other projection to prevent accumulation of snow and ice and to deflect water around the projection.

Cupola: A relatively small roofed structure set on the ridge of a main roof area. Also known as a Crow’s Nest.

Cupping: When shingles are improperly installed over an existing roof or are over-exposed, causing them to form a curl or cup.

Curb: A raised roof perimeter relatively low in height.


Dead level: Absolutely horizontal, or zero slope.

Deck: The structural surface to which the roofing or waterproofing system is applied.

Deflection: The deformation of a structural member as a result of applied loads.

Delamination: Separation of the laminated layers of a component or system.

Dimensional Shingle: A shingle that has a textured, laminated, or overlaid construction to produce a three-dimensional effect. Also called laminated or architectural shingles.

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

Double Coverage: Asphalt roofing application such that the lapped portion is at least 2″ wider than the exposed portion, resulting in two layers over the roof deck.

Downspout: A pipe for draining water from roof gutters to a lower level or the ground. Also called a leader.

Drip Edge: An installed lip that keeps shingles up off the deck at edges and extends shingles out over eaves and gutters to prevent water from wicking back.


Eave: The horizontal lower edge of a sloped roof.

Edge Venting: The practice of providing regularly spaced protected openings along a roof edge or perimeter to provide attic ventilation.

Expansion Joint: A structural separation between building elements that allows for free movement without damage to the roof.

Exposure: The portion of the roofing material exposed to the weather after installation.


Fascia: A vertical roof trim located at the perimeter of a building, usually below the roof line. In steep-slope roofing, a board nailed to the ends of rafters.

Felt: A flexible asphalt-saturated sheet manufactured from vegetable fibers, animal fibers, or glass fibers.

Fiberglass Mat: The core reinforcement material in asphalt shingles, made from glass fibers.

Fishmouth: An opening of a roofing material along an edge or cut, usually forming a “V” shape.

Flange: A projection edge of a roof accessory such as flashing that facilitates its attachment to the roof.

Flashing: Components used to weatherproof or seal the roof system edges at perimeters, penetrations, walls, expansion joints, valleys, drains and other places where the roof covering is interrupted or terminated.

Flutter: The lifting and vibration of lightweight metal caused by wind.


Gable: The upper triangular portion of an endwall beneath the ridge of a double-sloping roof.

Galvanic Action: Electrical current between two unlike metals that can accelerate corrosion.

Granules: Ceramic-coated colored crushed rock that is applied as a top surface on shingles and roll roofing to provide protection from UV degradation.

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


Hand-Sealing: The method to adhere roofing shingles in areas of high wind or on steep slopes, involving hand-applying roof cement or adhesive to the shingles.

Head Lap: The minimum overlap required at the ends of roofing materials such as shingles, measured from a fixed point to the butt edge of the upper course.

Headwall Flashing: Flashing used where a vertical wall meets a sloping roof plane, with the flashing applied in overlapping “step” fashion up the wall.

Hip: The inclined external angle formed by the intersection of two sloping roof planes.

Hip Roof: A roof that rises by inclined planes from all four sides.


Ice Dam: A build up of ice that forms at the lower roof edge, preventing proper water drainage and potentially forcing water back up under shingles and into the structure.

Ice Dam Protection Membrane: A self-adhering waterproof underlayment membrane installed along the eaves to prevent damage from ice dams.

Intake Ventilation: The part of a ventilation system used to draw fresh exterior air into the attic, i.e. soffit vents.

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


Joist: Any of the small timbers, metal or wood beams arranged parallel from wall to wall to support a floor, ceiling, or roof of a building.


Kick-Out Flashing: A type of flashing that diverts rainwater away from the cladding and into a gutter at roof-wall intersections.


Laminated Shingles: Asphalt shingles made up of two or more separate pieces that are laminated or fused together to create extra thickness.

Lap: To extend a course of roofing material beyond the course below, with the upper overlapping the lower.

Lap Cement: An asphalt-based cement used to adhere overlapping plies of roll roofing.

Low-Slope Roof: A roof with a slope less than 3:12 (25%).


Mansard Roof: A roof with two slopes on each of four sides, the lower slope is steeper than the upper.

Metal Drip Edge: A metal flashing or trim piece at the perimeter that facilitates water drainage away from the roof and protects underlying building materials.

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

Modified Bitumen: Rolled roofing membrane with polymer modified asphalt and either polyester or fiberglass reinforcement, installed as a two-ply system.


Nailing: The method of securing roofing materials to the deck using nails or other mechanical fasteners.

Nesting: A method of re-roofing with new shingles over existing where the top edge of the new shingle is butted against the bottom edge of the old shingle.


Open Valley: A method of valley construction in which shingles from both sides are trimmed along each side of the valley, exposing the metal flashing.

Organic Shingles: Roofing shingles made from organic – typically cellulose or wood fiber – mat. No longer produced.

Overhang: The part of the roof structure that extends beyond the exterior wall line.


Penetration: Any object that pierces the roof membrane such as pipes, stacks, skylights, chimneys, etc.

Pitch: The degree of roof incline expressed as the ratio of the rise, in feet, to the span, in feet. Also called slope.

Plastic Cement: An asphalt-based cement that can be used to seal or patch roofing. Should conform to ASTM D 4586.

Ponding: The accumulation of water at low-lying areas on a roof that remains long after surrounding areas have dried.

Primer: A thin, liquid bitumen that is applied to a surface to enhance the adhesion of subsequently applied self-adhering membranes or coatings.


Racking: A method of installing shingles where the shingle courses are applied vertically up the roof rather than laterally across and up.

Rake: The inclined edge of a roof over a wall.

Re-cover: The process of installing a new roof system over an existing roof system rather than tearing off the old.

Ridge: The highest point on the roof, represented by a horizontal line where two roof slopes meet.

Ridge Cap: The material applied over the ridge of a roof, covering the join between the materials on each side.

Ridge Vent: A ventilated covering for roof ridges that allows warm, moist air to escape from the attic.

Rise: The vertical distance from the eaves 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.


Saddle: A small raised area, similar to a cricket, that helps to channel roof drainage around projections like chimneys.

Sealant: Any material used to seal joints in roofing against leaks.

Self-Adhering Membrane: A bituminous roofing membrane material that can adhere to a substrate or to itself without additional heat or adhesives.

Self-Sealing Shingles: Asphalt shingles containing factory-applied adhesive strips that seal the shingles together once applied on the roof and warmed by the sun.

Shake: A thick, hand-cut shingle made from wood.

Shed Roof: A roof with a single slope.

Shiner: A roofing nail that missed its mark and is left exposed.

Shingle: A single unit of prepared roofing material, made from asphalt, wood, slate, tile or other material, that is applied in overlapping fashion with other shingles to form the roof covering.

Shingle Flashing: The inter-woven application of shingles with flashing at roof penetrations.

Side Lap: The amount by which a roofing material overlaps the piece below it as measured perpendicular to the eaves.

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

Soffit: The underside of any exterior overhanging section of a roof eave.

Soffit Vent: A vent on the underside of the eave that provides inlet ventilation.

Spalling: The chipping or flaking of a material surface, e.g., concrete or clay tiles.

Square: The amount of roofing material required to cover 100 sq ft of roof deck surface.

Starter Course: The first layer of roofing, applied along the eaves, on which all other layers are overlapped.

Starter Strips: 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.

Step Flashing: Individual pieces of sheet metal material used to flash walls, around chimneys, dormers or other vertical roof projections. Applied in a step fashion.


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

Telegraphing: The wrinkles, buckles or ridges that show through layers of a roofing system because of uneven decking below.

Torch-Down: Method of applying sheets of modified bitumen roofing where the back side of the material is heated with a torch as it is unrolled to adhere it to the substrate.

Transition Flashing: The flashing used where a steep-sloped roof meets a low-sloped or flat roof.


Underlayment: Asphalt-based rolled materials designed to be installed under main roofing material, to serve as added protection.

Underside Corrosion: Corrosion or rust that develops on the underside of metal roofing panels.

UV degradation: Deterioration caused by exposure to ultraviolet light from the sun’s rays.


Valley: The internal angle formed by the intersection of two sloping roof planes to provide water drainage.

Vapor Retarder: A material designed to restrict the passage of water vapor through the roof assembly.

Vent: Any outlet for air that protrudes through the roof deck such as a pipe or stack. Any device installed on the roof for the purpose of ventilating the underside of the roof deck.

Ventilation: The natural or mechanical process of exchanging air in an interior space and replacing stagnant, moisture-laden air with fresh air.


Waterproof: Impervious to water passage or damage under hydrostatic pressure.
Weathering: The effects of long-term exposure to weather on a roof’s surface or components.

Wind Uplift: The upward forces on a roof system or components caused by wind. Uplift forces can cause the roof system to be torn off or damaged if it is not adequately secured.

Wood Shake: A type of wood shingle that is hand split on at least one face, providing a textured, rustic look.

Wood Shingle: Thin rectangular pieces of wood used to cover roofs and walls, cut from softwoods like cedar or redwood and applied in an overlapping configuration.

Woven Valley: A method of valley construction in which shingles from both sides of the valley overlap each other. Shingles are woven together by overlapping alternate courses as they are applied.

Wrinkle: Ripples or buckles in a roofing membrane that may occur due to improper installation, excessive adhesive, or material defects.


Yard: Common term used for job site in reference to delivering materials for a roofing project, i.e. “deliver shingles to the yard.”


Zone, Roofing Application: The area of the roof deck where roofing materials are applied. Different areas may require specific materials or application techniques, such as high wind zones at the corners and perimeter.

So in summary, this glossary covers the key terms used in the roofing industry, from structural elements to materials to installation techniques and potential issues. Familiarity with these terms is important for effective communication between roofing professionals, building owners, and other stakeholders in any roofing project. The glossary is organized alphabetically for easy reference.

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