Glossary

This glossary was designed to help those not directly involved in roofing with their understanding of roofing terminology. Many technical and chemical terms were not included.

ICBO: International Conference of Building Officials, responsible for The Uniform Building Code.

Ice Dam: Ice formed at the transition from a warm surface to a cold surface, such as along the overhang of a house. The build-up of ice is the result of ice or snow melting on the roof area over the warmer, living area of a building and then refreezing when it runs down and reaches the overhang.

Ignition Temperature: The minimum temperature at which a material will combust.

Impact Resistance: A roof assembly’s ability to withstand the impact from falling objects such as hail.

Impregnate: To saturate; in roofing, asphalt impregnated fiber glass roofing felts are fiber glass mats that have been completely permeated with asphalt bitumen.

Infrared Thermography: The use of an infrared camera to detect moisture in roof insulation.

Inorganic: Involving neither organic life nor the products of organic life; relating to compounds not containing hydrocarbon groups.

Insect Screen: Material used to inhibit an insects ability to enter a building through openings in a roof such as vents.

Insulation: Material used to help maintain a certain temperature in a building by reducing the flow of heat to and from that building. See also Thermal Insulation.

Intake Ventilation: The part of a ventilation system used to draw fresh air in. Usually vents installed in the soffit or along the eaves of a building.

Interlayment: A waterproof material usually installed between adjacent rows of wood shakes to help with the roof’s waterproofing characteristics.

Interlocking Shingles: Shingles that lock together to provide wind resistance. See also T-Lock.

Internal Pressure: Atmospheric pressure inside a structure that correlates to the number and location of openings and air leaks.

Inverted Roof Membrane Assembly (IRMA®): A variation of the "Protected Membrane Roof Assembly" in which Styrofoam® brand insulation is used. 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 groups. A basic component in Sprayed Polyurethane Foam systems and some polyurethane coating systems.