Ice Dam
Ice formed at the transition from a warm to a cold roof surface. Typically formed at the over hang (eave). Snow melts down from the warm area of the roof, over attic space, to the eave where the temperature is the same as the ambiant temperature, where it freezes. Ice and water will then back up under roofing materials and can result in a leak. |
Impact Resistance
Resistance to fracture under sudden application of force. For example, shingle manufacturers are producing impact resistant shingles for hail prone areas. |
Impregnate
In regards to roofing materials; completely surround fibers in a felt or mat with bitumen. Spaces between the fibers are partially or completely filled without a continuous coating of bitumen on the surface. |
Infrared Thermography
The process of displaying variations of apparent temperatures over the surface of a roof by measuring the viariations in infrared radiance. |
Inorganic
composed of materials other than hydrocarbons and their derivatives, matter that is not of plant or organic origin. |
Insulation
Materials designed to reduce the flow of heat, either entering or exiting a building. |
Intake Ventilation
Fresh air 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 materials in times of wind driven precipitation. This method is typically used in wood shake installations. |
Interlocking Shingles
These are individual shingles that mechanically attach to each other. This provides additional wind resistance as they do not rely soley on sealing strips. |
Isolation Sheet
Refer to Slip Sheet |
Joist
Timbers, metal, or wood beams that are arranged parallel to each other, spanning from wall to wall, supporting a floor, ceiling or the roof of a building / structure. |
Laminate
To join layers of materials together. The process of joing layers of materials together utilizing ahesive / adhesion. |
Laminated Shingles
Refer to Dimensional or Archtectural shingles |
Liquid Applied
The application of bitumous cements, adhesives, coatings, applied at ambient or slightly above ambien temperatures (cold applied) |
Live Loads
Temporary in nature loads that the roof structure must be designed to support as set forth in govt building codes. Generally dynamic or environmental (installation equipment, snow, rain, ice, service personel etc) |
Loose Laid
Referring to a ballasted roof system whereas membrane is attached to the substrate only at the edges and the penetrations of the roof. Ballast is required as there are no field attachments along the roof with the exception of penetrations. |
Low Slope Roof
A roof with a pitch (slope) lower or lesser than 3:12 (14 degrees). Typically these roofs have membrane (single ply, EPDM, modified bitumen) roof systems installed as shingles are not meant to be waterproof, but to shed water.
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Low temperature flexibility
The ability of roofing material to flex, resist cracking when subjected to low temperatures. Particularly important on roofs where there may be anticipated foot traffic during winter months for maintenance. |
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