The method of fastening the back or upper side of a ply of roofing felt or other component in a roof system so that the fasteners are covered by the following ply.

A fine mineral material on the back side of roofing materials such as roll roofing to keep them from sticking together while packaged.

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.

Used for flat roofing systems.

They are usually welded to the supporting steel members and can span up to 4.5 metres (15 feet). The lightest and most efficient structural shape is the bar (or open web) joist, a standard truss made with angles for the top and bottom chords, joined by welding to a web made of a continuous bent rod. Also see Steel Joist

A roof configuration with a partial cylindrical shape to it. They have some advantages over dome roofs, especially being able to cover rectangular buildings, due to their uniform cross-section.

Plies of roof membrane material used to seal a roof at the vertical plane intersections, such as at a roof-wall and roof-curb junctures. (See also Flashing.)

The primary ply of roofing material in a roof system. It is secured to the deck over which a built-up roof is applied.

An asphalt-impregnated, or coated felt used as the first ply in some built-up and modified bitumen roof systems.

(1) A strip of wood usually fastened to the structural deck for use in attaching a primary roof system such as tile; (2) A plastic strip, wood strip, or metal bar which is used to fasten or hold the roof and/or base flashing in place, A.K.A. Termination Bar.

Battens are used for solid wall/roof insulation. Regularly spaced battens are fitted to the wall, the spaces between them filled with insulation, and plasterboard/drywall screwed to the battens. This method is no longer the most popular, as use of rigid insulation sheet gives better insulation (battens bridge the insulation) and takes less time to fit.

A metal roof that has a step profile. Usually runs perpendicular to the slope of the roof.

Small, inconsequential amounts of water on a roof that quickly evaporate.

Wire mesh installed over openings in order to prevent birds from entering a building or roof cavity.

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.

Bitumen is a black, oily, viscous material that is a naturally-occurring organic byproduct of decomposed organic materials. Also known as asphalt or tar, bitumen was mixed with other materials throughout prehistory and throughout the world for use as a sealant, adhesive, building mortar, incense, and decorative application on pots, buildings, or human skin.

Bituminous particles suspended in water or other solution. See also Asphalt Emulsion.

A continuous seal for preventing bitumen from leaking down into or off a building. Is constructed by extending the base sheet or other non-porous ply of felt beyond the edge of the field plies. It is then turned back onto the top of the system and adhered. See also Envelope.

See Tar Boil

A starter strip placed along rake edges for use in asphalt shingle roofing. A strip of polyester, acetate, or foil used in the production of sheet photopolymer plates in flexographic platemaking. See also Rake-Starter.

The use of nails so that they are not exposed to the weather in the finished roofing system. See Back-Nailing

A pocket of air trapped between layers of felt or membrane. Blisters are usually caused by water or other foreign substances on the roof.

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.

A small bubble found in the flood coat of an aggregate-surfaced built-up roof. See also Tar Boil.

The Building Officials and Code Administrators International (BOCA) is an association of professionals employed in the establishment and enforcement of BUILDING CODES, which are the rules and regulations that govern the design and construction of buildings. BOCA encourages cities and states to adopt uniform building codes, and promotes competence and professionalism in the enforcement of those codes.

The Building Owners and Managers Association (BOMA) International is an international federation of more than 100 local associations and affiliated organizations. Founded in 1907, its 16,500-plus members own or manage more than nine billion square feet of commercial properties. BOMA International’s mission is to enhance the human, intellectual and physical assets of the commercial real estate industry through advocacy, education, research, standards and information..

The force(s) holding two components in positive contact.

A chemical agent used to create a bond between two layers.