What are some low-slope roofing terms?
APP (Atactic Polypropylene): A modifier of asphalt (see modified bitumen roof membrane) that increases the UV resistance of the bitumen as well as its flexibility at low temperatures and improves its flow resistance at high temperatures.
Asphalt: A bituminous waterproofing agent applied to roofing materials during manufacture.
Built-Up Roof (BUR): A flat or low-sloped roof consisting of multiple layers of asphalt and ply sheets.
Base Sheet: A saturated or coated felt installed as the first ply in some multi-ply modified bitumen roofing assemblies.
Bitumen: (1) a class of amorphous, black or dark colored (solid, semi-solid or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons and found in asphalts, tars, pitches and asphaltines; (2) a generic term used to denote any material composed principally of bitumen.
Bituminous: Containing or treated with bitumen.
Cap Sheet: A granule-surfaced coated sheet used as the top ply of a modified bitumen roof membrane.
Coated Sheet or Felt: (1) an asphalt felt that has been coated on both sides with harder, more viscous asphalt; (2) a glass fiber felt that has been simultaneously impregnated and coated with asphalt or coal tar on both sides.
Cold-Applied Roofing: A continuous roof membrane, consisting of plies of felts, mats or fabrics that are laminated on a roof with alternate layers of cold-applied roof adhesive and surfaced with a cold-applied coating.
Deck: The structural surface to which the roofing or waterproofing system (including insulation) is applied.
Felt: A flexible sheet manufactured by the interlocking of fibers through a combination of mechanical work, moisture, and heat. Felts are manufactured principally from vegetable fibers (organic felts), glass fibers (glass fiber felts), or polyester fibers (polyester felts); other fibers may be present in each type.
Fiberglass Mat: An asphalt roofing base material manufactured from glass fibers.
Flashing: Pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection or projection in a roof, such as vent pipes, chimneys, adjoining walls, dormers and valleys.
Granules: Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.
Incline: The slope of a roof expressed either in percent or in the number of vertical units of rise per horizontal unit of run. Also referred to as slope.
Low-Fuming Asphalt: An asphalt that contains a small amount of special
polymer that, when heated, floats to the surface, creating a skim layer on
the asphalt in the kettle that traps most of the fumes.
Membrane: A roof covering or waterproofing layer whose primary function is the exclusion of water.
Modified Bitumen Roof Membrane: A continuous, semi-flexible roof membrane assembly consisting of plies of saturated felts, coated felts, fabrics or mats between which alternate layers of bitumen are applied, either surfaced or unsurfaced.
Organic Felt: An asphalt roofing base material manufactured from cellulose fibers.
Re-covering: The process of covering an existing roofing system with a new roofing system.
Re-roofing: The practice of removing an existing roofing system and replacing it with a new roofing system.
Roll Roofing: Asphalt roofing products manufactured in roll form, either smooth- or mineral-surfaced.
Saturated Felt: An asphalt-impregnated felt used as an underlayment between the deck and the roofing material.
SBS (Styrene-Butadiene-Styrene): A modifier of asphalt (see modified bitumen roof membrane) that enhances the bitumen’s ability to resist the effects of aging the weather.
Self-Adhering Membrane: A membrane that can adhere to a substrate without the use of an additional adhesive. The undersurface of a self-adhering
membrane is protected by a release paper or film, which prevents the
membrane from bonding to itself during shipping and handling. These
membranes can be base sheets, ply sheets, cap sheets or underlayments.
Smooth-Surfaced Roof: A roof membrane surfaced with a layer of hot-mopped asphalt, cold-applied asphalt-clay emulsion, cold-applied asphalt cutbacks, elastomeric coating, or sometimes with an unmopped, inorganic felt.
Square: A unit of roof measure covering 100 square feet.
Thermal Insulation: A material applied to reduce the flow of heat.
Underlayment: Asphalt saturated felt used beneath roofing to provide additional protection for the deck.
Vapor Retarder: A material designed to impede the passage of water vapor into the roofing system.