FAST-SET: A term applied to a coating to indicate a faster curing time versus a standard version of the generic coating. In polyurethane and polyurea coatings, this is generally indicative of cure times in the range of a few seconds to a few minutes, or coatings that must be sprayed with plural component equipment. In acrylic coatings, this is generally indicative of a 1–3 hour cure schedule versus a 2–5 hour cure schedule at 75°F.
FEATHERED EDGE: The thin tapered outside edge of a polyurethane foam pass.
FELTS: A flexible sheet manufactured by the interlocking of fibers through a combination of mechanical work, moisture, and heat. Roofing felts may be manufactured principally from wood pulp and vegetable fibers (organic felts), asbestos fibers (asbestos felts), glass fibers (fiberglass felts or ply sheet), or polyester fibers.
FERROUS METAL: An iron compound (i.e., steel, cast iron, or galvanized steel). As a rule of thumb, most ferrous metals are magnetic.
FILLER: A relatively inert ingredient added to coating or polyurethane foam formulations to modify their physical characteristics.
FILM THICKNESS: The thickness of a membrane or coating. Wet-film thickness is the thickness of a coating as applied; dry-film thickness is the thickness after curing. Film thickness is usually expressed in mm or mils (thousandths of an inch).
FIRE RESISTANCE: The inherent capability of a building assembly or an element of construction to resist the passage of heat, smoke, and flame; and/or to maintain structural integrity for a specified time during a fire. Usually measured by ASTM E 119.
FIREBLOCKING: Building materials or constructions designed, approved, and installed to resist the free passage of flame to other areas of the building through concealed spaces.
FIRESTOP: A material, device, or construction, installed to resist for a prescribed time period, the passage of flame and heat through openings in a protective membrane in order to accommodate cables, cable trays, conduit, tubing, pipes, or similar items.
FISHEYE: A coating defect that manifests itself by the separation of the wet coating into a recognized pattern resembling small “dimples” or “fish eyes.”
FISHMOUTH: Also referred to as an “edge wrinkle.” A half-cylindrical or half-conical shaped opening or void in a lapped edge or seam, usually caused by wrinkling or shifting of ply sheets during installation. In shingles, a half-conical opening formed at a cut edge.
FLAME RETARDANT: A substance that is added to a coating or polyurethane foam formulation to reduce or retard its tendency to burn.
FLAME SPREAD: Per ASTM E 84, a measure of relative combustibility. The flame spread of a tested material is rated relative to fiber cement board (flame spread = 0) and red oak flooring (flame spread = 100).
FLAMMABILITY: Relative ability of a material to support combustion as expressed by its flash point.
FLASH AND BATT: See HYBRID INSULATION.
FLASH COAT: A thin initial pass of a spray-applied material.
FLASH-IGNITION TEMPERATURE: The lowest temperature of a material required to initiate combustion in the presence of a spark or flame.
FLASHOVER: (1) A fire condition wherein gasses are ignited at the ceiling level of a room. (2) One of several measurements that are used to determine the threshold at which a fire test is terminated. Flashover can be a visual observation of flames exiting the structure or a measured heat flux or temperature limit.
FLASHPOINT: The lowest temperature of a material at which it gives off vapors sufficient to form an ignitable mixture with air near its surface.
FLASHING: The portion of a roof system used to waterproof at terminations or vertical surfaces.
FLUOROCARBONS: A chemical that contains both a carbon and a fluorine atom in its structure. They are traditionally used as physical blowing agents for polyurethane foam products. There are three common classes of these materials used as blowing agents: CFC, HCFC, and HFC. (See also CFC; HCFC; HFC.)
FLUTES: The grooves in the lower section of metal decking that give it added strength.
FM: See FM GLOBAL.
FM APPROVALS: A division of FM Global (formerly Factory Mutual or FM) that certifies industrial and commercial products and services as meeting its established safety standards for insurance rating purposes, and which publishes such certifications in its Approval Guide.
FM GLOBAL: Formerly Factory Mutual or FM. A United States-based insurance company that specializes in loss prevention services. The company employs a business model that determines risk and premiums through engineering analysis as opposed to historically based calculations. (See also FM APPROVALS.)
FMRC: Factory Mutual Research Corporation. A part of FM.
FOAM STOP: The roof edge treatment upon which polyurethane foam is terminated.
FREEZE-THAW CYCLE: The freezing and subsequent thawing of material.
FRIABILITY: The tendency of a material or product to crumble or break into small pieces easily.FROTH PACK: Pressurized containers of polyurethane foam components.
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