If you're a commercial building owner, there's a good chance you've heard of built-up roofing (BUR). Historically referred to as tar roofing or tar and gravel roofing, BUR is a tried and true, low-maintenance, flexible type of commercial roofing system. If you're looking for more information about BUR roofing and what it can do for your commercial building, here's what you need to know about tar and gravel roofing.
What is BUR?
BUR is an acronym commonly used to describe the methods of built-up roofing. When BUR was first developed in the late 1800s, it was installed in layers of tar and jute. Over the years, BUR has changed, giving commercial building owners different options depending on their needs.
Built-up roofing is typically made of three elements: bitumen material (or coal tar), ply sheets, and surfacing materials. To create BUR, alternating layers of fabric and asphalt are applied to the roof. Once the layers have been fully applied, the final layer of gravel is laid down on top.
Although TPO is currently the most popular flat and low slope roofing application, BUR is still a consideration due to its long lifespan. Built-up roofing techniques can even be used to create garden roofs. Many commercial property owners prefer BUR because the reinforcing fabric and asphalt create a sealed, continuous surface that prevents water from penetrating the structure.
Types of BUR
There are three types of built-up roofing — hot BUR, cold BUR, and ballasted BUR.
- Hot Built-Up Roofing - Hot BUR is made from heated, liquefied asphalt. The traditional tar and jute BUR is a perfect example of hot BUR. Today’s hot built-up roofing sheets are often made from fiberglass instead of jute.
- Cold Built-Up Roofing - Cold BUR uses the same materials as hot BUR, the bonding agent is considered "cold" because it does not have to be heated in order to be liquefied. Compared to hot BUR, the adhesive used in cold built-up roofing doesn’t release fumes during installation and can be installed during various weather conditions.
- Ballasted BUR - Unlike hot and cold BUR, Ballasted roofing systems are not bonded with any type of adhesive. Instead, the membrane is anchored to the roof with a layer of large rocks, often gravel. Ballasted BUR relies entirely upon the gravel or rocks to hold the roofing material in place.
Pros of BUR
So why use BUR? The benefits of this roofing type are numerous.
Commercial roofs may feature solar panels, air conditioners, and other fixtures or appliances. These fixtures must be accessible for maintenance purposes. BUR is built to withstand years of walking, stomping, and other activities as maintenance workers access these fixtures.
Most maintenance problems on BUR roofing are easy to fix. While built-up roofing may be prone to cracks, blisters, or undulating waves, patches are easily installed to remedy these issues.
The materials used for built-up roofing protect the roofing structure from damaging UV rays. Some types of BUR can even absorb heat, which can help with cooling costs during warmer seasons or in hot climates.
Since the flammable materials on any BUR roof are buried under a thick layer of rock or other material, roof-top fires easily burn out. BUR has a higher fire rating than many other types of roofing, making it the perfect solution for commercial properties.
Commercial building owners seeking a roof that can last for three or four decades at a time typically turn to BUR to get the job done. Although the installation of this type of roofing is more labor intensive, it is durable and typically low maintenance.
If you have a built-up roof and want to know your options, the commercial roofing experts at Pickard Roofing can provide built-up renewal or other less expensive options, such as TPO. Contact us today to find out more about installing built-up roofing on your commercial property.
At Pickard Roofing, we think Design. Craft. Renew. We are experienced in all types of roofing systems- and provide the right roofing design and selective craftsmanship for renewing our customer’s assets. We invite sustainable building customers to give us a call for your free evaluation. For over 90 years Pickard Roofing Company has installed countless metal, tile, slate, TPO, EPDM, and all types of shingle roofing in the Triangle. Our services include residential, commercial, custom architectural metal fabrication, and historical renovation.