Built-up roofing is also known as BUR roofing. It is sometimes referred to as hot-mop or hot-asphalt roofing, as well. Among commercial flat roof systems, it is certainly the most commonly used system today and has been around for over 150 years and has a long track record of performance.
Built-up roofs consist of several plies of roofing material, each applied in sequence to the roof, and bonded together by the waterproofing element and adhesive, which is hot asphalt. The number of plies and the type of ply material can vary from specification to specification, with the higher number of plies and higher quality of plies yielding the longer life span of the roof. The ply sheets act as a reinforcing component of the system, and they strengthen the asphalt and help keep the system intact when as it is exposed to the elements.
In addition to the ply sheets, a surfacing layer is applied over the system to help protect it from foot traffic, ultra violet damage, and air pollutants. This surface layer, in addition to be a protective layer, is also an aesthetic layer – most often this layer is a granulated fiberglass capsheet membrane, but it may also be aggregate (gravel) that is embedded using a final flood coat of hot asphalt. This layer gives the roof the finished appearance that owners have come to expect. Capsheet is cost effective and requires only limited maintenance, and repairs to a capsheet surface are relatively easy – gravel surfacing presents much more of a challenge to repair, later on.
In some cases, this surfacing layer also can serve as a reflective surface, to rebound incoming solar radiation from the sun, keeping the roof surface cooler and therefore reducing air conditioning costs for the building itself. These “cool roof” capsheets are designed to reduce energy usage and meet state energy saving requirements, such as Title 24, here in California. When selecting a BUR roof system, it is imperative that the choice is tailored to the specific project. Consult with your Ferguson & Melvin representative for recommendations for your job.
Built up roof systems are most recommended for commercial flat roof installations, where cost is the highest concern, and where asphalt fumes would not be a disruption to tenants, occupants, or students. These systems are quick to install and because they are so common, installers are not difficult to find. Their biggest advantage is redundancy – because there are multiple layers applied, and because the waterproofing is being applied in liquid form (hot asphalt), the chance of leaks are reduced substantially, even if the installation is not perfect. However, if applied incorrectly, like any other roof system, they can still have major problems.
And another thing to consider is the quality of the asphalt that is available today in California. Environment regulations have forced asphalt manufacturers to alter their formulations over the last 15 years. Many installers, including Ferguson & Melvin Co., that have been around for more than two decades, can attest that the asphalt does not hold up like it used to. BUR roof systems that used to last 20 years or more are sometimes starting to fail in less than 10 years. Because of that, many owners now prefer instead to go with a torch applied APP modified bitumen system or with a single-ply roofing system.
Ferguson & Melvin Co. supervises all of our BUR roof installations and guarantees the highest level of quality and service from our staff on the roof and in the field. We strive to provide the best suitable BUR roofing product, designed to meet your roofing needs.
Call our office today at (800) 974-ROOF or click here to request a quote.