Commercial roofers lay this noncombustible insulation layer directly over a steel or wood roof deck before applying hot asphalt, torch-down membranes, or other roofing systems. It acts as a thermal break and a fire shield, preventing the intense heat of installation or an external fire from igniting the underlying structure. It also provides a smooth, stable substrate for the waterproofing layers above.
We've to lay down a half-inch barrier board over the plywood deck before we can break out the torches for the modified bitumen.
Skipping this layer on a combustible deck when using a torch-applied roof is a massive code violation and a fast way to burn down a building.
Also heard as
- thermal barrier
- fire barrier board
Related terms
Roof assembly
The complete system of interacting components that form a building's roof, from the structural deck up to the weatherproofing layer.
Built-up roof
A flat roof covering made of alternating layers of bitumen and reinforcing fabrics.
Torch
To point or fill the inside joints of roof slates or tiles with mortar.