Built-up roofing, known more commonly as BUR, is widely considered the “original” roofing system. Having been around for over 100 years, it has been a reliable flat roof staple of the industry for as long as modern commercial roofing has been done!
BUR has a reputation as one of the strongest and most resilient roofing systems thanks to its redundant, multi-layered design. That means when taken care of properly, your roof lifespan has the potential to far outlast other single-ply roofing systems, but that comes at the cost of a more expensive (more material and labor) and invasive (think strong smell of hot asphalt) installation.
But that’s just the tip of the iceberg! In the blog below, we’ll take you through any and everything you need to know about BUR roofing systems and what makes them such a popular and time-tested option in the commercial roofing industry!
What is BUR Roofing?
BUR roofing is built-up roofing in the most literal sense: it’s installed directly on top of the building structure it’s covering by adding multiple layers of roofing. These resilient roofing systems are “redundant,” meaning they’re composed of multiple layers. Single-ply membrane roofs like TPO and EPDM, on the other hand, are only composed of one roofing material layer.
The first layer of a BUR roof will be some type of insulation, followed by 4-5 layers of fiberglass felt and hot asphalt on top of that (or sometimes a cold-processed adhesive). Last but not least a layer of surfacing at the top to protect your roofing system from wear and tear.
What Unique Advantages Does BUR Roofing Have Over Other Roofs?
For starters, BUR roofing systems traditionally have a longer lifespan than most other roofing systems. This of course is assuming you’re performing biannual roofing inspections and completing all routine maintenance and repairs in a timely fashion.
A well maintained BUR system can last around 30-40 years when properly maintained. That’s a huge upside compared to the 20-25 year average lifespan of many other major roofing systems.
A built-up roof requires less maintenance than other roof types, due to a high puncture resistance contributing to a lower probability of getting an emergency leak from an accidental puncture compared to other roofing systems. A commonly overlooked benefit of BUR roofing is its ability to maintain traction. If your roof has a lot of foot traffic, the gravel on a BUR system provides a great grip and resistance to heavy foot traffic.
Warranties for BUR roofing systems are relatively standard but, as always, are dependent on the manufacturer. Some specialty manufacturers offer a 35 year warranty while other generic manufacturers offer a standard 20 year warranty.
BUR roofs are more resilient to foot traffic and overall abuse, meaning they’re harder to damage than other single-ply membrane roofs. Thanks to its multiple layers, it’s harder to create accidental penetrations that result in costly leaks. That means less overall maintenance and fewer repair costs over its lifetime.
Common BUR Roofing "Surfacing" Layers
The most common “surfacing,” or the top-most layer of a commercial roofing system, for BUR roofs is called a “flood coat and gravel.” This involves the pouring of a hot adhesive that’s then topped with gravel to help bond it together. A flood coat and gravel layer is the most heavy-duty surfacing option but it’s also one of the more challenging surfaces to find leaks on.
Another BUR roofing surfacing option is “smooth built-up”, which means the top-ply layer is left bare and coated with aluminum or another roof coating that becomes your UV resistant topping layer.
How Much Do BUR Roofing Systems Cost?
BUR roofs are inherently more expensive than other major commercial roofing systems. Why? For one, BUR roof installations require special equipment, which can drive up the overall project costs. In addition to equipment and labor, BUR roof installations also require more raw material because of their multiple layers.
At first glance, built-up roofing material can seem relatively cost-effective at only around $40 for a roll that covers 300 sq ft. This may seem low compared to modified bitumen roofing material, which costs about $70 per roll and only covers around 100 sq ft.
The difference is that modified bitumen roofing systems only require 2 layers of material while BUR roofing systems require 5 layers. More material, more labor, and more equipment means a more expensive commercial roofing system.
What BUR Roofing Installation Options Exist?
With many commercial roof systems, there are a variety of installation options to choose from based on your location, building type, or budget. For example, modified bitumen roofs offer hot asphalt, cold application, torch application, and self adhering installations, just to name a few.
With BUR roofs, however, majority of installations we perform are hot asphalt simply because very few manufacturers offer cold processed installation options.
How Are BUR Roofing Systems Repaired?
As with all roofing types, damages to your commercial roof should be taken care of as quickly as possible to prevent any additional damage or leaks. It’s equally important to ensure that all repairs should be conducted by a certified commercial roofing contractor.
Generally repairs on BUR system involve removing the topping layer (i.e gravel) to the plies, preparing, cleaning, and patch repairing with new modified bitumen membrane.
Google is full of tips and tricks for ways to complete roof repairs manually, but these shoddy DIY methods not only jeopardize the integrity of your roof and/or the validity of your manufacturer’s warranty, they also delay the inevitable: your commercial roofing system needs the expertise of a commercial roofing contractor.
BUR roofing systems are known to have more involved repairs, and additional labor almost always means additional project costs. Don’t let this deter you from picking up the phone when you notice an issue: no matter what repairs your BUR roof may need, the cost will always increase the more you delay!
Higher upfront costs could mean significantly lower overall costs over the course of 30+ years. Lucky for you, Simpson Unlimited has installed countless BUR roofing systems on every major building type across Virginia, Maryland, and DC, meaning you can rely on our expertise.
To hear more about BUR roofing systems, or if you’re thinking it might be the right roofing system for your building type, send us your details and we’ll get to work right away!