Build Up Roofing - BUR Roofing
What is BUR Roofing?
A built-up roofing system, also called BUR roofing, is the most prevalent roofing system that you will find on low-slope roof structures. It is comprised of alternating layers of fabric used for reinforcement, along with bitumen (which consists of asphalt), and is completed with a top coat of aggregate, which may be stone or gravel. BUR roofing is the preferred option for a low-slope or a flat roof as it forms a fully sealed membrane over the structure of the roof. Other options, like roof shingles, do not provide a full seal and utilize the slope of the roof to effectively remove water.
Varieties of Built-Up Roofing Systems
Modern build-up roofing products make use of a rigid layer of insulation to increase energy efficiency.
Most built-up roof systems contain three distinct parts: the bitumen material, ply sheets, and at least one surfacing material. The bitumen may be applied hot, which means it is heated to a point that liquefies it as it is installed, or it can undergo a cold installation, that acts as an adhesive without being heated. A cold built-up roof system is possible to spray on or apply with a squeegee. The material goes on clean so there are no toxic fumes as it is applied and it is not weather dependent. The cold method provides improved performance over hot BUR roofing.
The ply sheets included in the build-up roofing are fabrics that are specially designed and reinforced with fiberglass or other organic materials. Each layer of the ply sheet material is installed on top of the hot or cold bitumen material, bonding it in place on the roof. The ply sheets are usually constructed in standard widths of 36 inches.
The final layer, surfacing materials finish off the visible top-coat of the BUR roof system using small stones or very fine gravel, according to the application required. This top layer does more than just complete the look of the roof, as it also protects the lower layers from UV-rays and damage from debris, whether it’s unnatural or weather-related. A flat roof buildup gives the roof a safe surface to walk on.
There is a unique build-up roofing option known as ballasted roofing, which uses larger sized stones of roughly 1.5 to 2.5 inches in diameter to finish the surface layer. On a ballasted roofing system, the bottom layers are not secured to the roof structure as the standard BUR roofing would be, as the weight of the top surface layer holds the entire built-up roof system in place.
The Lifespan of a Built-Up Roof System
Based on the weather conditions over time and the types of materials used, build-up roofing customarily lasts anywhere from 15 to 30 years. However, some BUR roofing can survive for up to 40 years. Generally, a flat roof build-up system usually does better under warmer conditions than in colder regions of the country. This lifecycle of the built-up roofing system is quite comparable to asphalt shingles, which ordinarily last about 15 and 30 years, but that depends on the quality of the roofing material.
There are some roofing materials that can last much longer but may also be more costly. These include standing seam metal roofing systems, which you can expect to have for approximately 50 years, while slate roofing may last you for up to a century.
What is the greatest advantage of having BUR Roofing?
Built-up roof systems offer outstanding waterproofing and ultra-violet protection. The aggregate top layer of the roof also provides excellent fire-resistance. Build-up roofing ordinarily requires very little maintenance, so once installed, there is little in the way of additional cost to make the roof last as long as possible.