Glossary of Roofing and Waterproofing Terms
ICBO: International Conference of Building Officials. Author of The Uniform Building Code.
Ice Dam: 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.
Ignition Temperature: the minimum temperature to which a solid, liquid, or gas must be heated in order to initiate or cause self-sustained combustion independent of the heating element.
Impact Resistance: the ability of a roofing material to resist damage (e.g., puncturing) from falling objects, application equipment, foot traffic, etc. The impact resistance of the roofing assembly is a function of all of its components, not just the
Impregnate: 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.).
Incline: the slope of a roof expressed either in percent or in the number of vertical units of rise per horizontal units of run. (See Slope.)
Infrared Thermography: 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 Thermal Image.)
Inorganic: 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.
Insect Screen: wire mesh used to prevent insects from entering the building through ventilators, louvers, or other openings.
Insulation: any of a variety of materials designed to reduce the flow of heat, either from or into a building. (See also Thermal Insulation.)
Intake Ventilation: the fresh air that is drawn into a passive ventilation system through vents typically installed in the soffit or eave of a roof.
Interlayment: 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 winddriven rain and snow. Typically used with wood
Interlocking Shingles: individual shingles that mechanically attach to each other to provide wind resistance.
Internal Pressure: pressure inside a building that is a function of ventilating equipment, wind velocity, and the number and location of openings and air leaks.
Inverted Roof Membrane Assembly (IRMA`): 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.
IRWC: Institute of Roofing and Waterproofing Consultants
ISANTA: International Staple, Nail & Tool Association
Isocyanate: a highly reactive organic chemical containing one or more isocyanate (-N=C=O) groups. A basic component in SPF based systems and some polyurethane coating systems.