Common Roofing Terms Defined & Explained
With all the different terminology related to the roofing industry, we have provide the following list of terms or phrases commonly used in the roofing industry. Each term is accompanied by a brief definition.
Rooftop fungus that can leave dark stains on roofing.
Roofing nails and staples driven into the decks at angles not parallel to the deck.
Metal flashing used at chimney fronts.
Shrinkage cracking of the bituminous surface of built-up or smooth surface roofing, producing a patter of deep cracks resembling an alligator hide.
A bituminous waterproofing agent used in various types of roofing materials. It is a highly viscous hydrocarbon produced from the residuum left after the distillation of petroleum.
Asphalt Concrete Primer
Asphalt based primer used to prepared concrete and metal for asphalt sealant.
Asphalt Plastic Cement
Asphalt based sealant material, meeting ASTM D4586 Type I or II. Used to seal and adhere roofing materials. Also referred to as mastic, blackjack, roof tar, and bull.
The American Society for Testing and Materials. Organization that sets standards for a wide variety of materials, including roofing.
An anchoring material (such as rock, gravel, pavers) used to resist wind uplift forces of roof membrane.
Base flashing forms the upturned edges of watertight membrane.
Commonly referred to as purlins. Battens are generally 1″x2″x4″ wood strips nailed to the roof decking or rafters for the roofing material to be attached to. This is to give a secure base to anchor the roofing materials to because OSB will hold screws efficiently.
Blister / Blistering
A spongy raised portion of roofing membrane as a result of pressure from entrapped air or water vapor. In shingles blisters are caused by either moisture under the material or moisture trapped inside the material.
When shingles are subjected to high winds, and are forced off a roof deck.
When a wrinkle or ripple affects shingles or their underlayments.
Built-up roofing (BUR)
A continuous semi flexible roof covering consisting of laminations or plies of saturated or coated felts alternated with layers of bitumen.
A continuous strip of triangular cross-section, fitted into the angle formed by a structural deck and a wall or other vertical surface, and used to provide gradual transition for base flashing and horizontal roof membrane.
To fill a joint with mastic or asphalt cement to prevent leaks.
Highest fire-resistance rating for roofing. Indicates that roofing material is able to withstand severe exposure to fire originating from sources outside the building.
Fire-resistance rating that indicates roofing materials are able to withstand moderate exposure to fire originate from sources outside the building.
Fire-resistance rating that indicates roofing materials are able to withstand light exposure to fire originating from outside the building.
Closed Cut Valley
A shingle valley installation method where one roof plane’s shingles completely cover the others’s. The op layer is cut to match the valley lines.
Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening. Also referred to as a pipe boot.
The metal or siding material that is installed over the roof-top base flashing systems. Counter flashing is installed on the exposed edges and joints of the base flashing to prevent water from migrating behind the base flashing.
A break in a roofing membrane as a result of flexing, often occurring at a ridge or wrinkle.
A peaked water diverter installed behind chimneys and other large roof projections. Effectively diverts water around projections and prevent ice accumulation of snow and ice.
When shingles are improperly installed over an existing roof or are over-exposed, they may form a curl or cup. May also be due to a manufacturing defect.
The substrate over which roofing is applied. Usually plywood, wood boards, or planks. A commercial roof deck may consist of metal or concrete.
A raised roof extending out of a larger roof plane.
An installed lip that keeps shingles up off the deck at edges, and extends shingles out over eaves and gutters, and prevents water from returning back into roof. Prolongs life-expectancy of fascia and exterior finishes.
EPDM (Ethylene Propylene Diene Monomer)
A synthetic rubber sheet used in single ply roof membrane.
A deliberate separation of two roof areas to allow expansion and contraction movements of the parts.
The roof edge from the fascia to the structure’s outside wall. Generally the first three feet across a roof. This is the protective overhang at the lower edge of a sloped roof.
Engineered Wood Association, Tests and sets standards for all varieties of plywoods used in the U.S.
Area’s on a roof that are exposed to natural elements.
The finish member covering the edge or eaves of a flat or sloping roof or roof overhang.
Nails or staples used to secure roofing to the deck.
A flexible sheet that is saturated with asphalt and used as an underlayment, sometimes called “tar paper.”
Fibers that are wove and condensed into strong, resilient mats for use in various roofing materials.
An opening of the lapped edge of applied felt in built-up roofing due to adhesion failure.
Metal pan extending up or down a roof slope around flashing pieces. Usually at chimneys and plumbing vents.
Materials used to waterproof a roof around any projections. Connecting devices that seal membrane joints, drains, gravel stops and other places where membrane is interrupted.
Sealant designed for use around flashing areas, typically thicker than plastic cement.
The upper portion of a sidewall that comes to a triangular point at the ridge of a sloping roof. Trim that goes on this part of a roof is called gable or rake trim.
Traditional roof style where two roof planes meet a ridge line of equal size. Contains a gable each end.
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.
Crushed rock that is coated with ceramic coating and fired, used as top surface on shingles.
Flanged device, normally metallic, designed to prevent loose aggregate from washing off roof. It also provides a finished edge detail for built-up roofing assembly.
This method is used on very steep slopes, high wind areas, and when installing in cold weather to ensure that a proper seal is made.
When shingles are nailed or fastened above the manufacture’s specified nail location.
The inclined external angle formed by the intersection of two sloping roof planes. Runs from the ridge to the eaves.
The down-slope ridges on hip roofs.
A roof with four roof planes coming together at a peak and four separate hip legs. This type of roof does not contain a gable.
When a snow load melts on a roof and re-freezes at the eave areas. Ice dams force water to back-up under shingles and cause leakage. Ice dams may be caused by a roof without proper ventilation.
The part of a ventilation system used to draw fresh air in. Usually vents installed in the soffit or along the eaves of a building.
Continuous metal flashing consisting of several feet of metal. Used at horizontal walls, pre-fabed to resemble the letter L.
Shingles made form two separate pieces that are laminated together. These shingles are also referred to as dimensional and/or architectural shingles.
Laps / Lap Seams
The areas on a roof where roll roofing materials (including underlayments) overlap one another when installed.
A roof with one slope only that is built against a higher wall.
Low Slope Applications
Methods of installing roofing material on roof slopes between 1-2 inches per foot.
Roof pitches less than 4/12 are generally considered low sloped roofs. Only certain roofing applications can be applied on roofs with slopes of 2/12 – 4/12. Generally shingles can not be installed at slopes less than 2/12 (varies by city/county building code requirements).
A roof design with a nearly vertical roof plane that ties into a roof plane of less slope at its peak. This type of roof contains no gables.
Base material of shingles and certain rolled roofing products.
Asphalt with the addition of polymer modifiers to increase cold temperature flexibility and warm temperature flow resistance and stability. Reinforcement material is made of polyester or fiberglass.
Nail Guide Line
Painted line on laminated shingles, to aid in proper placement of fasteners.
When a nail not fully driven into roofing material and sits up off the roof deck.
Installing a second layer of shingles aligning coursed with the original roof to avoid shingle cupping.
Valley installed using metal down the middle of the valley of the roof.
Mat material made from recycled wood pulp and paper.
Shingles are made from organic (paper) mats.
Oriented Strand Board. A decking made from wood chips and lamination glues.
The term used for fasteners driven through roofing material with too much force, breaking the roofing material/materials.
Installing shingle coursed higher than their intended exposure.
The portion of the roof structure that extends beyond the exterior walls of a building. Return to top.
PVC (Poly Vinyl Chloride)
A generic term for single ply plastic sheet membrane. The seams are fused by solvent or hot-air welding techniques.
The part of the wall entirely above the roof.
Refers to the incline on the roof. The number of inches rise per 12 inches horizontal. Example: 2/12 means that there is two (2) inches rise per twelve (12) inches horizontal.
Plumbing Vent Flashing
Prevents rainwater from running into holes cut for pipes in the roof. This flashing is sold according to the size of the vent pipe and the roof angle. Roofing material is installed over the flashing.
Plywood is often used for roof decks. It is a strong, durable and lightweight wood material. The thickness of plywood depends on the spacing of the rafters.
The collection of water in shallow pools on the roof surface.
Horizontal lengths of material, wood or metal, that are affixed to the roof and to which the finished roofing material is attached to.
The vertical edge of gable style roof planes.
The installation of a new roof system over an existing system without removing the existing roofing system. Referred to as an overlay.
Installing a new roof system on an existing structure that is not newly built.
The horizontal line formed by the juncture of two sloping planes, especially the line formed by the surfaces at the top of a roof.
Hard plastic ridge vent material.
The vertical distance from the eaves line to the ridge.
Rooftop rectangular shaped roof vents. Also called box vents, mushroom vents, airhawks, soldier vents.
A roofing area defined by having four separate edges. One side of a gable, hip, or mansard roof.
The horizontal distance from the eaves to a point directly under the ridge. One half the span.
Sealant installed on shingles. After installation, heat and sun will activate sealant to seal the shingles to each other.
The non exposed are on rolled roofing without granules. Designed for installation to sealant.
Exterior grade boards used as a roof deck material.
Roof structure of single roof plane. It is an area that doe not tie into any other roofs. Does not contain any hip, ridges, valleys or gables.
The area on rolled roofing material where one roll overlaps the rolled material beneath it. Also called the selvage edge on rolled roofing.
Area where a vertical roof plane meets a vertical wall. Such as on the sides of dormers, etc.
The ratio between the measures of the rise and the horizontal span.
The finish on the underside of a roof overhang.
Intake ventilation installed under the eaves, or at the roof edge.
The horizontal distance from eaves to eaves.
This the first course of roofing installed on a new asphalt roof. This is sometimes trimmed from the main roof material.
Steep Slope Roofing
Generally all slopes/pitches higher than 4/12 are referred to as steep slopes.
Metal flashing pieces installed at sidewalls and chimneys for waterproofing.
One roofing square is equal to 100 square feet – 10′ x 10′ area.
The bottom portion of a traditional shingle separated by the shingle cut-outs.
Removal of existing roofing materials on roof down to the deck. This includes removing existing underlayment.
When shingles show signs of unevenness due to the underlayment or existing shingles beneath them.
Tongue and Groove
If a roof can be seen on the underside such as from an interior ceiling view, tongue and groove is used in place of plywood or OSB. It is a wood decking that provides great insulation without additional rigid roof insulation in moderate climates.
When a roof plane ties into another roof plane that has a different pitch or slope.
Description for a fastener that is not fully drive flush to the shingle surface.
Asphalt based rolled materials designed to be installed under main roofing material to serve as added protection.
The “V” created where two sloping roofs meet. This is where two roofs join at an angle.
Term used to describe moisture laden air.
Any outlet for air that protrudes through the roof deck such as a pipe or stack. Any devise installed on the roof, gable or soffit for the purpose of ventilating the underside of the roof deck.
The finished wall inside of a structure, used in roofing to determine how far up the deck to install waterproof underlayments at eaves.
The written promise to the owner for materials and labor.
Modified bitumen based roofing underlayments. Designed to seal to wood decks and waterproof critical leaks areas.
The method of installing valleys by laying one shingle over the other up the valley center.