There are two main types of burs or tar and gravel roofing systems modified bitumen roofs which are a mix of asphalt and rubber with a layer of gravel on top and ballast roofing which is a different style of larger gravel applied on top of a single ply roofing system.
Pictures of bur roofing.
A built up roof is frequently called a bur in technical literature.
Bur is preferred for low slope or flat roofs because it creates a continuous sealed surface.
Built up roofing also called bur is the most common roofing material used on low slope roofs.
Low moisture excellent dimensional stability and resistance to rot make it an ideal replacement for organic cap sheets.
Developed in europe in the mid 1960s modified bitumen roofing has been used in canada and the united states since about 1975.
The colloquial term tar and gravel refers to built up roofs.
Components of a bur system include the roof deck a vapor retarder insulation membrane and surfacing material.
Provide protection to the underlying bitumen and membrane and have a low maintenance cost.
Meets the requirements of astm d 3909.
A traditional bur system gets its name from the building of a roof on site using layers of base sheet interplay sheets and cap sheet or other surfacing such as gravel or liquid coating.
Modified bitumen built up roofing.
It is composed of alternating layers of reinforcing fabric and bitumen asphalt and is finished with a top layer of aggregate such as stone or gravel.
Glaskap is used as a cap sheet in a variety of built up roofing systems.
Asphalt coated fiber glass reinforcement mat.
Built up roofing or bur is the most popular choice of roofing used on commercial industrial and institutional buildings.
Bur is used on flat or low sloped roofs and consists of multiple layers of bitumen and ply sheets.
It was developed as a means to improve roofing membranes when product quality was affected by the use of a lower quality crude oil by product.