Roofing Glossary of Terms





Roof Vent Pipe Field of Roof System Ridge Flashing Hip Soffit Gable Rake Drip Edge Valley Gutters Underlayment Eave Vent
Factory Mutual Research Corporation (FMRC)As it relates to roofing - a division of Factory Mutual System that tests and classifies roof components and systems for their resistance to fire, traffic, impact, weathering, and wind-uplift. The various organizations of Factory Mutual are owned or directed by Allendale Insurance, Arkwright, and Protection Mutual Insurance.
Factory SeamA splice/seam made in the roofing material by the manufacturer. It is preferable during installation to cut these splices out of the membrane.
FadingLosing brightness or brilliance; dim.
FallbackA reduction in the softening point temperature of asphalt that occurs when asphalt is overheated for pro-longed periods of time. See also Softening Point Drift.
FasciaVertical roof trim located along the perimeter of a building, usually below the roof level. Its use can be either decorative or for waterproofing.
FastenersDevices used to secure roof system components.
Feathering StripsStrips of wood that are placed along the butt ends of wood shingles to form a somewhat smooth surface so that the shingles can be roofed over without removal.
FeltA roofing sheet made of interwoven fibers. The fibers can be wood or vegetable for Organic Felts, glass fibers for fiberglass felts, polyester, or asbestos.
Felt MachineA machine that will install bitumen and felt at the same time.
FerruleA metal sleeve used as a spacer to keep gutter from being beat up when secured to fascia with spikes.
Fiberglass InsulationInsulation composed of glass fibers used to insulate walls and roofs. It can be rigid board or blanket insulation.
Field of the RoofRefers to the central part of a roof away from the perimeter.
Field SeamA non-factory material seam made by joining overlapping seams together with adhesives, heat welders, or other means.
FillerAn inert ingredient added to roofing materials in order to alter their physical characteristics.
FilletA sealant material installed at horizontal and vertical planes to remove 90° angles.
FilmA membrane or sheeting material with a nominal thickness of 10 mils or less.
Film ThicknessThe thickness of a membrane or coating that is expressed in mils (thousandths of an inch). See also Wet Film Thickness and Dry Film Thickness.
FinA sharp protrusion in a roof deck that can damage roof components.
Fine Mineral-SurfacingA fine mineral material on the surface of roofing materials to prevent them from sticking to surfaces. 50% of this material has to pass through a sieve with holes that are 1/35" in size (#35 sieve).
FishmouthAn opening along the exposed edge of an installed ply of felt caused by shifting the ply during installation. Repair these by making a slice along their entire length and feathering two plies of felt over the fishmouth for a minimum coverage of one foot all the way around.
FlakingOccurs when a coating loses its cohesion.
Flame RetardantA substance used to impede a material’s tendency to burn or ignite.
Flame SpreadA measure of relative combustibility. The flame spread of a tested material is rated relative to asbestos cement board (flame spread = 0) and red oak flooring (flame spread = 100).
FlammabilityThe ability of a material to burn or ignite.
FlangeA projection edge of a roof component such as flashings, skylight frames, pre-manufactured curbs, etc. Usually refers to the part that sits on the roof surface.
Flashv. To install flashing components.
Flash PointThe lowest temperature of a liquid material at which combustion will occur when air reaches its surface.
FlashingComponents used to seal the roof system at areas where the roof covering is interrupted or terminated. For example, pipes, curbs, walls, etc. all have special components that, when correctly installed, will help prevent moisture entry into the roof system or building.
Flashing CementA trowelable mixture of solvent-based bitumen and mineral stabilizers. Flashing cement that may contain asbestos stabilizers is categorized by ASTM standard D 2822-91 (1997) or for non-asbestos, ASTM standard D 4586-93. Flashing Cement is the term for Asphalt Roof Cement that can be used on vertical surfaces and has a high softening point, low ductility and conforms to the requirement of ASTM Specification D 312, Types II or III; or Specification D 449, Type III. See also Asphalt Roof Cement and Plastic Cement.
Flashing CollarA flashing component used to seal soil pipe vents, hot stacks or other roof penetrations.
Flat LockA type of interlocking two separate metal panels by folding one panel over on top itself and the folding the other down under itself and then hooking the panels together.
FleeceMats or felts used as a membrane backer and composed of fibers.
Flood CoatThe surfacing layer of bitumen into which aggregate is embedded on an aggregate-surfaced built-up roof. A flood coat is applied at an approximate rate of 45 to 60 pounds per square (100 square feet).
Flood TestA water test performed to determine the effectiveness of a roof covering.
FlowTo become fluid in character.
Fluid-Applied ElastomerA liquid elastomeric material that cures to form a continuous waterproofing membrane.
FMShort for Factory Mutual Research Corporation
Foam StopThe edge metal used to terminate Sprayed Polyurethane Foam
Framed OpeningAn structurally-framed opening in a roof of a building for use in installing large items such as HVAC units, skylights, or ventilators.
Froth PackA term used to describe small, disposable aerosol cans of SPF.




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Rough Estimator

Roofing contractors have a language all their own. Don’t get bogged down by the jargon. Check out the glossary for clear, simple definitions of roofing terminology.