Modified Bitumen Roofing

Built-up roof (BUR) membranes

Commonly known as BUR, built-up roof membranes have been in use for more than a century. These materials are mostly made up of several alternating layers of bitumen and reinforcing fabrics (roofing felts, or ply sheets) that form a roof membrane.

The bitumen mostly used in built-up roof systems is asphalt, cold-applied adhesive, or coal tar.

The hot-applied tar mixes with the bitumen saturated reinforcing fabric to create a monolithic roof membrane. The roofing felt is applied in overlapping layers until the assembly is two or four plies thick.

BUR systems are considered to be totally adhered if applied directly to roof decks or insulation.

Surfacings for built-up roofs include mineral surfaced cap sheets, aggregate, hot asphalt mopped over the entire surface, elastomeric coatings, aluminium coatings, or glass-fibre.