a division of Factory Mutual System that tests and classifies roof elements and systems for their resistance to fire, visitors, impact, weathering, and wind-uplift. The numerous organizations of Factory Mutual are owned or directed by Allendale Insurance, Arkwright, and Protection Mutual Insurance.

A splice/seam made in the roofing material by the manufacturer. It is preferable throughout installation to cut these splices out of the membrane.

Losing brightness or brilliance : dim

A 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.

Vertical roof trim located along the perimeter of the creating, usually beneath the roof level. Its use may be both decorative or for waterproofing. Fascia board is a kind of roof trim which is commonly utilized on houses. It is mounted around the exposed ends of rafters or even the leading of exterior walls to make a layer between the edge with the roof and the outside. In addition to serving an aesthetic function by making a smooth, even look around the edge with the roof, fascia board also protects the roof and also the interior of the home from weather damage. Not all styles of house style feature fascia board, but numerous do.

Roofing fasteners are devices that are used to secure roofing system components in place. Fastening systems are imperative to the integrity of the roof.

Feathering Strips are usually strips of wood that are placed along the butt ends of wood shingles. They form a smooth surface so that the shingles can be roofed over without having to remove them. This can make a new replacement roof much easier to work on and reduce the cost.

Roofing Felt is a roofing sheet that is made of interwoven fivers. The fibers can consist of several different materials including wood or vegetable for Organic Roofing Felts, some are made of glass such as fiberglass felts as well as polyester and asbestos felts. The felt is used as a moisture barrier between the wood and the outside. For example, shingles are not sealed and moist air can get through a shingle. If you were to hit a shingle upward, they can leak and cause damage to the roof. The felt paper acts as another barrier keeping outside moisture and humid air from penetrating through to the wood.

Spikes and ferrules maintain the gutter towards the wall with the house. The ferrule is inserted within the gutter and the spike is driven through the rim of the gutter and through the ferrule to maintain the gutter in place.

Insulation composed of glass fibers used to insulate walls and roofs. It can be rigid board or blanket insulation.

Fibers condensed into strong, resilient mats for use in roofing materials.

Refers to the central part of a roof away from the perimeter.

A non-factory material seam made by joining overlapping seams together with adhesives, heat welders, or other means.

An inert ingredient added to roofing materials in order to alter their physical characteristics.

A sealant material installed at horizontal and vertical planes to remove 90° angles.

A membrane or sheeting material with a nominal thickness of 10 mils or less.

The thickness of a membrane or coating that is expressed in mils (thousandths of an inch). See also Wet Film Thickness and Dry Film Thickness.

A sharp protrusion in a roof deck that can damage roof components.

A 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).

An 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.

Occurs when a coating loses its cohesion.

A substance used to impede a material’s tendency to burn or ignite.

Per ASTM E 84, a 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).

The ability of a material to burn or ignite. The degree of difficulty required to cause the combustion of a substance is quantified through fire testing. Internationally, a variety of test protocols exist to quantify flammability

A 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.