BUR is one of the oldest roofing systems, which commenced over 100 years ago. BUR offers the added protection of multiple layers which performs well in extremes of heat, cold, wind and snow. It is also easy to repair. It consists of multiple layers of roofing materials with asphalt or bitumen in-between each layer. It is a very reliable roofing system while meeting economical demands.

The choice of felts, organic (paper) or inorganic (fiberglass) is installed in an overlapping fashion starting at the low points of the roof surface. Each ply of felt is adhered to the next in a full mopping of asphalt or cold adhesive. Typical BUR systems incorporate a 4-ply application, although different variations and specifications require three to five plies with a top pour and protective surfacing.

Rigid insulation used for BUR systems is typically Polyisocyanuarate (ISO) closed cell, foam core insulation laminated with fibreglass facers to provide a rigid, durable surface, for use with almost all roofing applications. Polyisocyanurate can be installed using fasteners and plates, asphalt or cold adhesives. Polyisocyanurate RSI values are very high, providing maximum insulating value from minimal material thickness. Other rigid insulations including EPS, XPS and Fiberglass base-cap have been commonly used in the industry.

​Typical BUR system incorporate pea stone gravel surfacing embedded into an application of hot asphalt or cold adhesive. The gravel provides the roofing system with ballast and acts as an protective layer to reduce the effects of heat, UV degradation and moisture, which can degrade the asphalt systems very quickly. The gravel also provides protection against foot traffic.

​This final hot asphalt application seals the entire roof uniformly. All four layers completely adhered as one. This surface is level now allowing for the last application of ballast to be spread over the roof, now water tight and rigid.