Thermal Break

A thermal break is a strip of insulating material that is inserted into a building assembly to prevent rapid heat conduction through dense, highly conductive materials such as metal and masonry.

1. The spaces between steel studs and steel rafters can be insulated effectively and economically with glass fiber batts, but the steel framing members themselves will continue to conduct heat through the wall or roof at a very high rate. The framing members in this case arc referred to as thermal bridges, meaning that they furnish a way for heat to flow easily through an otherwise well-insulated assembly, much as a road bridge furnishes a way for traffic to flow readily across an otherwise impassable obstacle. In detailing, we block a potential thermal bridge with a thermal break, which is made of a material with a low thermal conductivity. In the example shown here, the thermal bridges are steel studs in a wall, and the thermal breaks consist of strips of plastic foam that are placed between the exterior cladding material and the studs. Although one of these thermal breaks may not insulate the framing member to the same thermal resistance value as the insulated space between the members, it gready reduces the flow of heat through it, and it raises the temperature of the indoor side of the member enough so that moisture will not condense on it. The steel screws that pass through the thermal break constitute another set of thermal bridges, but they are so small in cross section that little heat flows through them. O

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