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.

 

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.).

 

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 wind-driven rain and snow. Typically used with wood shakes.

 

Interlocking Shingles: individual shingles that mechanically attach to each other to provide wind resistance.

 

Inverted Roof Membrane Assembly (IRMATM): a patented, proprietary variation of the “Protected MembraneRoof Assembly” in which Styrofoam® Brand Insulation and ballast are placed over the roof membrane. IRMATM and Styrofoam® are registered trademarks of the Dow Chemical Company.

 

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