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Asphalt Built-up roof (BUR) has been the most common type of roof system that has been applied over the years. The Built up roof system consists of multiple layers of reinforcing plies and asphalt forming a redundancy of water proofing layers.
The plies used in today’s BUR’s are made from fiberglass mats embedded into asphalt. The fiberglass mats have replaced the asbestos mats that were widely used before being found to be harmful to the workers.
St. Louis, MO:
-- Williams American Construction, Inc. 958 County Road 6460. Salem, Mo. 65560 -- 314.799.2757 or 573.453.0000 Fax: 573.729.2744 --
OSHA regulations are of high importance to Dale Williams, and the staff at Williams American Construction. Our staff takes annual OSHA training classes in order to stay abreast of all new and current Safety, as well as Health guidelines.
Asphalt BUR Built Up Roofing Systems St Louis Mo
A BUR can be applied to multiple specifications such as a Three Ply up to a Six Ply and even as a base roof moisture barrier before installing a single ply. The surface of the last ply requires coating in order to offset harmful UV-rays when the BUR is the only roof application. As the UV rays, moisture and aging degrade the surface coatings of the BUR’s it is necessary to continue to apply maintenance coatings at regular intervals being about 3-5 years depending on the surface coating material that is selected.
Some notes about the asphalt used for built up roof applications:
The asphalt is an aliphatic compound and in almost all cases a byproduct of the oil industry. As asphalt ages it shrinks and forms a surface similar to alligator skin, referred to as alligatoring. As it ages, the asphalts melt point rises and there is a loss of plasticizers. Asphalt breaks down slowly in water , and the more exposure the more rapid the degradation. Asphalt will dissolve rapidly when exposed to oils and chemicals including sugars that are released by internal ventilation at large baking manufacturing plants.
There are four types of roofing asphalt. Each type is created by heating and blowing the asphalt with oxygen. The longer the process the higher the melt-point of the asphalt. Type I asphalt has characteristics closes to coal tar pitch and can only be used on dead level surfaces. Type II, is considered flat and can be applied to surfaces up to ¼ in 12 slopes. Type III, is considered to be “steep” asphalt but is limited to slopes up to 2 in 12, and Type IV is “special steep”. The drawback is, the longer it is processed, the shorter the life. Gravel has been applied to the surfaces of the built up roofs in order to offset the weathering effects but this makes repairs very difficult. Cool Roof (Energy Star Rated), non tar, White Elastomeric coatings may protect the felts for many years and becomes the best application for sustaining the roof systems for many years.
Asphalt Built Up Roofing Systems (BUR) St Louis Mo