Experts in commercial roofing are often asked about their thoughts on the distinct types of roofing systems available – which is best? Which is most affordable? Which is best for for long-term durability? This blog investigates the differences between two of the more popular commercial roof choices: single-ply membrane and built-up roofing systems.

The Facts About Single Ply and BUR Systems

Single-ply membranes are roofing sheets made of rubber and other synthetic materials. They are adhered to the insulation with a chemical process which creates a protective layer over the roof.There are two primary kinds of single-ply membrane commercial roofing: Thermoplastic Polyolefin (TPO) and Ethylene Propylene Diene Terpolymer (EPDM). There are some differences between the two, including their chemical makeup, installation requirements and energy efficiency.
The installation process of either TPO and EPDM single-ply membrane roofing systems starts out in a similar manner. After preparing the current substrate, the insulation will be installed and covered by a cover board. There are three basic methods to adhere the membrane to the cover board: ballast, adhesive, or mechanical fasteners. The major difference between TPO and EPDM is evident when membrane seams are sealed. TPO utilizes a hot-air gun to melt down and then fuse the membranes at the seams, while EPDM is connected with seam tape.When correctly installed and routinely maintained, a commercial single-ply membrane roof can last for up to three decades. Benefits of single-ply membrane roofing systems include:
- Reliability and Reputation: EPDM roofing has been a standard for commercial flat roofing for over sixty years.
- Options for Insulation:Single-ply membrane roofing systems allow customers to choose from a variety of options to insulate the roof.
- Class A Fire-Rated: TPO membranes and EPDM can achieve Underwriters Laboratories (UL) Class A fire resistance listings by adding fire retardant chemicals to their manufacturing process.
- Reflective or Retentive Properties: TPO is typically white and highly reflective of solar rays, while EPDM or “Black Roofs” can retain heat.
Built-up roofing systems have been in use in the U.S. for over a century. More commonly known as “tar and gravel” roofs, built-up systems alternate layers of asphalt/tar and supporting fabrics directly onto the surface of the roof. The contractor will work with the building manager to select the number of layers (or plies) that are installed, with the top layer made of stone or gravel. When installed, the first layer of a BUR roof adheres directly to substrate of the roof. If it is required, a base sheet can be installed on the roof to create a flat and safe surface on which to work. A BUR system alternates layers of bitumen and reinforced fabric in three, four, or five-ply roofs. The top layer is comprised of rock or stone, protecting the lower layers from UV rays, extreme temperatures and damage from wind. Some propety managers choose to add gravel for aesthetic purposes. When correctly installed and routinely maintained, a commercial built-up roof can last for over four decades. Other benefits include:
- Seamless and Waterproof: The solid surface does not need seams or joints, making the surface less vulnerable to leaking.
- Reflective: The roof offers protection from harmful UV rays.
- Low-Maintenance: Minimal maintenance is required after installation.

Roof Coatings Repair Most Roof Tops

Regardess of the type of roof you have on your building, at some point the roof will begin to erode and deteriorate in some areas. The good news is that a full roof replacement is often not necessary – instead, each of these roofs can be repaired with professional roof coatings that can significantly extend the life of the roof.

If you are concerned about the condition of your commercial roof, or you simply want an inspection to get a baseline, call the experts at Unicoat Industrial Roofing. We have the expertise, knowledge and skill you need to protect your roof for decades more.