International Conference of Building Officials. Author of The Uniform Building Code.

(1) A mass of ice formed at the transition from a warm to a cold roof surface, frequently formed by refreezing meltwater at the overhang of a steep roof, causing ice and water to back up under roofing materials; (2) Condition formed at the lower roof edge by the thawing and refreezing of melted snow on the overhang. Can force water up and under shingles, causing leaks.

The ability of a roofing membrane to resist damage (e.g., puncturing) from falling objects, application equipment, foot traffic, hail, etc. The impact resistance of the roofing assembly is a function of all of its components, not just the membrane itself.

(1) The process of coating and surrounding a reinforcing mat or fabric with a soft matrix material; (2) To coat, saturate and/or surround the fibers of a reinforcing mat or fabric with an enveloping liquid material (e.g., bitumen, elastomeric compound, etc.)

Inch

The slope of a roof expressed either in percent or in the number of vertical units of rise per horizontal units of run. See PITCH and SLOPE.

A practice of roof system analysis where an infrared camera is used to measure the temperature differential of a roof surface to locate areas of underlying wet or moist insulation. See used to measure the temperature differential of a roof surface to locate areas of underlying wet or moist insulation. See THERMAL IMAGE..

(1) Being or composed of materials or matter other than hyrdocarbons and other derivatives; or matter that is not of plant or animal origin; (2) Any chemical or compound that is derived from minerals, does not contain carbon, and is not classified as organic; being or composed of materials other than hydrocarbons and their derivatives; not of plant or animal origin.

Wire mesh used to prevent insects from entering the building through ventilators, louvers or other openings.

Any of a variety of materials designed to reduce the flow of heat, either from or into a building. See THERMAL INSULATION.

The fresh air that is drawn into a passive ventilation system through vents typically installed in the soffit or eave of a roof.

(1) A felt, metal or membrane sheet material used between courses of steep-slope roofing to improve the weather- and water shedding characteristics of the primary roof covering during times of wind-driven rain and snow. Typically used with wood shakes; (2) A layer of felt or nonbituminous saturated felt not less than 18" (457 mm) wide, shingled between each course of a wood-shake roof covering.

Individual shingles that mechanically fasten to each other to provide wind resistance.

Pressure inside a building that is a function of ventilating equipment, wind velocity, and the number and location of openings and air leaks.

A patented, proprietary variation of the Protected Membrane Roof Assembly in which Styrofoam Brand Insulation and ballast are placed over the roof membrane. IRMA and Styrofoam are registered trademarks of the Dow Chemical Company.

Institute of Roofing and Waterproofing Consultants.

International Staple, Nail & Tool Association