Built-up Roofing (BUR): What Is It & How Does It Work?

Built-up roofing systems (BUR) are a popular choice for buildings with a flat or low-sloped roof. Made of alternating layers of bitumen (asphalt) and reinforcing fabric (fiberglass), the surface of BUR systems is layered with fine gravel or small stone. 

Types of Built-up Roofing

Common built-up roof types include:

• Hot Built-up Roof

In hot BUR, the bitumen is heated and liquefied during installation. As a result, installing hot BUR roofs can be tricky, as roofers have to work with heated materials.

• Cold Built-up Roof

Here, the bitumen is cooled and used like an adhesive. Cold BUR roofs can be applied or sprayed with a squeegee. They do not emit toxic fumes and are not affected by weather fluctuations. Also, these roofs perform better than hot built-up roofs.

• Ballasted Asphalt Built-up Roof

The surface layer of this roof uses heavy stones that keep the roof in position. This means that the lower layers don’t need to be fastened or adhered to the roof structure.

Advantages of Built-up Roofing System

• Weather Resistant

Built-up roofs contain tar or coal tar, which does not catch fire easily. The tightened bitumen layer also keeps water away from the building. The fiberglass coated with aggregate makes the roof sturdy, ensuring ultimate protection against extreme weather conditions (such as hail storms and strong winds).

• Energy Efficient

The BUR roofing system has a reflective coating that protects against UV rays which helps keep the building cool. Therefore, you can save a considerable amount on your electric bill.

• Easy to Maintain

Generally, these roofs are installed in large sheets having a lower profile than shingles. As a result, the material is less likely to damage and therefore does not require frequent maintenance.

How Does a BUR Work?

A built-up roof system is made of three parts: bitumen, ply sheets, and surfacing material.

• The bitumen can be hot or cold. If required, you can fasten the base sheet before placing this layer to create a sturdy and safe workplace.
• The ply sheets consist of special fabrics that are reinforced with organic material or fiberglass and are laid over the bitumen layer for bonding.
• The top layer is coated with an aggregate for overall aesthetics and durability. A reflective coating can also be added to facilitate cooling.

How Long Does a BUR Last?

A built-up roof can last for 15 to 40 years, depending on the climate, construction, and materials used. Generally, these roof systems perform better in warmer regions. A built-up roof system is undoubtedly the best roofing system for commercial buildings due to its extensive weather protection, durability, and high energy efficiency. All you need to do is to hire a professional roofing contractor to ensure proper installation. If you are looking for the best commercial roofing company in Orange County and Los Angeles for your roofing needs, contact Applied Roofing Services today at 714-632-8418 or get a quote online.