BUR roofing is a viable solution for flat roofs.
In addition to modified bitumen torch down, ethylene propylene rubber and polyvinyl chloride (PVC), BUR is a type of roofing process used on flat roofs. BUR stands for Built-up Roof, which, as the name suggests, consists of a layering of different materials. The technique and materials may vary slightly depending on the contractor's preferences.
Materials
In BUR roofing, the roof substrate is first covered with rosin paper, which will serve as a protective layer between the roof substrate and the roofing paper. BUR roofs are then built up with alternating layers of fiberglass felt paper and asphalt. The roof is then covered with a layer of crushed granite, pea gravel or the alternative to rock: an aggregate coated sheeting material. Gravel or aggregate sheeting will help protect the asphalt from sun damage.
Requisites
BUR roofing can be applied on new constructions or older roofs, as long as the roof substrate is sound and solid. BUR roofing can be installed on wood, concrete, steel or a layer of polystyrene insulation boards. BUR roofing can be installed on flat roofs or roofs with a slope no greater than 12 inches. Older roofs will need to have original roofing material removed, and any damages to the substrate have to be repaired.
Process
The layers of rosin paper and felt paper are unrolled in rows from sheets and can be easily cut with a utility knife. The layer of rosin paper and first layer of felt paper are tacked down with roofing nails. Flashings around pipes and vents are installed on top of the first layer and are primed to ensure that the asphalt will stick to the metal. Subsequent layers of felt paper are adhered by the tar in between. Tar is applied hot by mopping it onto the roof. Gravel or the aggregate coated sheeting material is then installed.
Advantages
BUR roofing has historical precedence amongst flat roofing materials and continues to be popular. Advantages include the durability and longevity created by the layers, and affordability as compared to other processes. BUR roofing also has insulation and thermal properties and will make the building more energy-efficient. The gravel layer is also fire-resistant and is attractive if it is to be seen from upper levels that overlook the roof.
Disadvantages
Disadvantages include weight, as once completed the combination of materials is quite heavy. To support this weight, the roof substructure and joists must be solid. Gravel can also fall into gutters and other channels and inhibit the proper drainage of water. Because of the gravel covering, leaks can be difficult to locate. Hot asphalt also has an unpleasant odor and can be messy to work with.
Tags: roofing, material, felt paper, flat roofs, roof substrate, rosin paper, aggregate coated, aggregate coated sheeting, aggregate coated sheeting material, coated sheeting, coated sheeting material, covered with, first layer
