Built-up bituminous roofing or BUR is the grandfather of membrane roofing
. It remains popular and significant enough in the marketplace, even more than it was in the 1970s through 1980s. Many commercial property owners have shown an increased interest in this type of roof due to its eco-friendliness and sustainability. Therefore, it is relatively fair to view where it really stands today and if there are any questionable issues.
When it comes to recycling topics, BUR has always been and still is at the forefront of green technology. Asphalt is the derivative of petroleum conversion into diesel, gasoline, heating oil, and mineral spirits. It is cost effective, especially when used in large volume for roof and pavement installations. Coal-tar pitch is the derivative for turning coal into coke. Coke is subsequently used in the production of aluminum. Coal tar pitches and asphalt are both classified as bitumen in the United States. They can be both heated and then used as felt coatings and reheated to be used as an adhesive in constructing roof membrane.
Recycled paper or glass is used to reinforce the built-up bituminous roofing. For slate roofs, metal panels, asphalt shingles, and tile roofs, saturated roofing felt continue to be the standard underlayments. Nationally, asphalt shingles that have glass fiber reinforcements have been the most dominant in the marketplace. Laminated shingles carry warranties of up to thirty years. No warranties are offered when the PV panels have been directly mounted on and through the laminated shingles.
The fundamental thermal insulations that roofing contractors use with BUR has been traditionally glass fiber, wood fiber, and perlite fiber boards. These all contain a considerable amount of recycled materials. Isoboards serve as the best in higher thermal resistance today. For alternative insulation to board stock, roofers will use insulating fills that are light in weight. It allows better slope draining, which is especially helpful for photovoltaic roofs.
Roofing contractors will often use about sixty pounds of asphalt for each roofing square for conventional surfacing of BUR. Stone is also embedded into it. The bitumen offers waterproofing of the roof membrane. On the other hand, the aggregate offers a balance to prevent the flow of the flood coat, which is being applied to the roofing square. It also offers a screening from UV rays and a surface that is resistant to fire.
The BUR membrane used between the 1930s or the 1940s may have consisted of a couple of asphalt saturated felts. These would be laid on the roof deck with three additional felts embedded in hot asphalt. This will result in the replacement of the dry ply sheets laid by a base sheet coated with asphalt. The base sheet is mopped or nailed, depending on its substrate.
The Dissolution Aspect
Due to its ease in dissolving in mineral spirits, asphalt can serve as the base for roof coating, primer, flashing mastic, and plastic cement. It can emulsify and aluminized easily, providing a reflective coating. While applying BUR is usually done using hot asphalt from an asphalt spreader or mop, there are also available adhesive systems that are solvent based and just as effective.
There is a bright future for BUR as people adapt to a green way of living. If you are interested in learning more about a green roofing system for your commercial building, the Roof Doctor
can assist you. Contact us today at 303-618-9889 to discuss your specific needs.