Roofing Glossary of Terms
Commercial roofing terminology.
aggregate pavers: a surfacing or ballast for a roof system. Aggregate can be rock, stone, crushed stone or slag, water-worn gravel, crushed lava rock, or marble chips.
alligatoring: the cracking of the surfacing bitumen on a built-up roof that produces a pattern of cracks similar in appearance to an alligator’s hide.
aluminum: a non-rusting metal used in roofing for metal roofing and the fabrication of gutter and flashings.
Amalgamated™ Tapered Insulation System: a roofing system developed by Pinnacle Roofing Systems which uses multiple, increasing tapers that become steeper toward the edge of a flat roof in order to provide better insulation distribution, avoid ponding, and allow for more adequate drainage as roofs age.
asphalt: a bituminous waterproofing agent applied to roofing materials during manufacturing.
asphalt emulsion: a mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.
ballast: a material installed over the top of a roof membrane to help hold it in place. Ballasts are loose laid and can consist of aggregate or concrete pavers.
batten: a strip of wood usually fastened to the structural deck for use in attaching a primary roof system such as tile; or a plastic strip, wood strip, or metal bar which is used to fasten or hold the roof and/or base flashing in place.
bitumen: any of various flammable mixtures of hydrocarbons and other substances, occurring naturally or obtained by distillation from coal or petroleum, that are a component of asphalt and tar and are used for surfacing roads and for waterproofing.
blocking: pieces of wood built into a roof assembly used to stiffen the deck around an opening, support a curb, or for use as a nailer for attachment of membranes or flashing.
boot: a piece of material preformed to protect roof penetrations from dirt, moisture, and other foreign and/or damaging substances.
built-up roof/BUR: a roof consisting of multiple layers of reinforcing membrane and waterproofing materials, such as asphalt and ply sheets.
cant strip: a continuous strip of material (triangular in cross-section) used as a transition piece between the roof deck and a vertical surface, normally with a 45 degree sloping surface; or a continuous strip of wood or fiber fitted into an angle formed at the intersection of a horizontal surface and a vertical surface.
cap flashing: material used to cover the top edge of base flashings or other flashings.
cap sheet: one to four plies of felt bonded and top coated with bitumen that is laid over an existing roof as a treatment for defective roofs.
contractor’s warranty: the written promise to the owner of the roof and roofing materials for workmanship involved in roofing or re-roofing a building.
curb: a raised member used to support skylights, HVAC units, exhaust fans, hatches, or other pieces of mechanical equipment above the level of the roof surface; or a raised roof perimeter that is relatively low in height.
deck: the surface installed over the supporting framing members to which the roofing is applied.
deterioration: having become disintegrated and impaired in quality, functioning, or condition.
drainage: the act, process, mode of, or device for draining.
drip edge: a non-corrosive, non-staining material or steel flashing bent at a 90 degree angle that is placed along the outer perimeter of steep sloped buildings; used along the eaves and rakes to allow water run-off to drip clear of underlying construction.
drippage: bitumen material that drips through roof deck joints, or over the edge of a roof deck.
eaves: the horizontal, lower edge of a sloped roof.
EPDM: Ethylene Propylene Diene Monomer; a thermoplastic rubber with high tear strength that can be cross-linked by both peroxides and sulfur.
evaluation: the careful appraisal of a roofing system to determine the condition and functionality of its various components and to recommend any necessary or potential need for repair or maintenance.
FM: an abbreviation of Factory Mutual Research Corporation; an insurance-industry, standards-setting laboratory.
fascia: vertical roof trim located along the perimeter of a building, usually below the roof level, for waterproofing or decoration.
flashing: components used to seal the roof system in places where the roof covering is interrupted or terminated – such as around pipes, curbs, walls, etc. – to help prevent moisture entry into the roof system or building.
flat roof: a non-peaked roof, typically used on industrial or apartment buildings, which appears flat but has a slightly tapered pitch.
HVAC: heating, ventilating, and air conditioning equipment.
inspection: the checking or testing of roof system and its components against established standards.
insulation: material used to maintain a desired temperature in a building by reducing the flow of heat into and out of the building.
maintenance: the periodic scheduled upkeep of a roofing system.
manufacturer’s warranty: the written promise to the owner of the roof and roofing materials for material-related problems.
membrane: the portion of the roofing system that serves as the waterproofing material.
new roof: an entirely new roofing system, usually placed on new construction.
parapet wall: the part of a perimeter wall that extends above the surface of the roof.
perimeter: the outer boundary of a roof or roofing system.
pipe boot: a prefabricated flashing piece used to flash around circular pipe penetrations.
pitch: the degree of slope or steepness of the roof.
polymer: any of numerous natural and synthetic compounds of usually high molecular weight consisting of up to millions of repeated linked units, each a relatively light and simple molecule.
ponding: the accumulation of water at low-lying or sagging areas of a roof.
proposal: a document stating the terms and conditions of a proposed roofing project submitted to a prospective client for approval and signature following a visual inspection of the project site and condition, or new building plans and specifications.
R-value: the measure of a material’s resistance to heat flow. The higher a material’s R-value, the more it insulates.
rakes: the inclined edge of a sloped roof over a wall from the eave to the ridge.
repair: the fixing of leaks, deterioration, cracks, and other such problems on an existing roof system.
re-roof: the replacement of a roof or portion of a roof, or the placement of additional roofing materials over an existing structure.
roof deck: the component in building construction which forms a platform on which the remainder of the BUR components are placed.
roof system: the entity made up of multiple roof components assembled to provide waterproofing, weatherproofing, and insulating for a building, including the waterproof covering, roof insulation, vapor barrier, and roof deck.
sag: settling or drooping of base flashings that have not been properly secured to a surface, or due to aging and deterioration, often occurring toward the center of a roof away from the perimeter.
scuppers: an outlet in the wall of a building or a parapet wall for drainage of water from a flat roof.
slope: the angle of incline of a roof.
straight tapered system: a slightly tapered roof in which the pitched surface sheds water toward a building’s perimeter.
substrate: the surface that the roof is installed upon.
termination: the sealed edges of a roof membrane.
underlayment: a layer of material (often tar paper) which is laid down on a bare deck before shingles are installed to provide additional protection for the deck.
white roof: a reflective roof that is more effective than traditional black asphalt roofs in keeping solar heat out of buildings and increasing energy savings.