Single-Ply vs. Built-Up: Which Is More Energy-Efficient?

Cool roofs are a must for commercial buildings because they make the hot weather more bearable for occupants. According to a study, cool roofs can reduce city center daytime air temperature by 32.9 to 37.4 °F and Urban Heat Island effect (UHI) by 23 percent. Energy Star adds that cool roofs can give seven to 15 percent savings in cooling costs and reduce peak cooling demand by 10 to 15 percent.

So what is a cool roof? We’ll answer this question by talking about one excellent example: single-ply roofing systems.

What Is Single-Ply Roofing?

As the name suggests, single-ply roofing consists of a single membrane made up of various synthetic materials, rubber, and insulation, all put together using chemical adhesives, fasteners, or weighted down with a good amount of ballast (e.g., gravel, stones, pavers).

Single-ply roofing membranes come in two types: thermoplastic polyolefin (TPO) and ethylene propylene diene terpolymer (EPDM). These materials are responsible for single-ply roofing’s reputation as energy-efficient commercial roofing solutions:

• TPO is a 0.060-mil membrane made up of three bonded layers: thermoplastic polyolefin at the base and top, and a scrim layer or polyester-reinforced fabric at the center. TPO usually has a white surface, which enhances its reflective quality. All things considered, TPO membranes do a good job of reflecting UV rays and reducing heat transfer into the building. So when people speak of a “cool roof,” they are often referring to TPO single-ply roofs because they reflect more sunlight and absorb less heat.
• EPDM is also synthetic, this time made with a flexible rubber compound. EPDM roofs were widely used in commercial facilities since the 1960s. Since it is made from rubber, it is often black and looks like the inner side of a tire. It is less reflective than the white TPO, but it does an excellent job of retaining heat during the cold season.

Both types of single-ply roofing are energy efficient because they help maintain a cool, comfortable temperature inside the building. Single-ply roofing can reduce heating and cooling energy consumption by deflecting UV rays, lowering the UHI during a heatwave, and preventing heat from escaping through the roof during winter.

Old Meets New: How Single-Ply Roofing Compares to Built-Up Roofing

Single-ply is the newer alternative to the more traditional built-up roof system or BUR.

BUR roofing has been used in the U.S. since about a hundred years ago. Many buildings all over the country still have these “gravel roofs,” which is a testament to BUR’s longevity. It just happens that the benefits of single-ply roofing now eclipse the advantages of BUR systems.

What Is Built-Up Roofing?

Built-up roofing is the “tried and tested” commercial roofing option inspired by asphalt roofing techniques. It is made up of many layers of asphalt, tar, and fabrics, then capped off with gravel as the topmost layer. Building owners can decide on the number of layers based on factors like budget, construction time-frame, weight, and ease of installation.

BUR provides excellent insulation and can also improve a building’s energy efficiency. It is a sound commercial roofing solution, but it does come with disadvantages.

The Pros and Cons of Built-Up and Single-Ply Roofing

Here is a summary of the pros and cons of BUR and single-ply roofing systems:

Pros

• Built-Up Roofing: Seamless, waterproof, low-maintenance, UV-resistant, fire retardant
• Single-Ply Roofing: Cool roofing, heat, and UV-resistant, fire retardant, lightweight, quick and easy to install, more affordable than BUR

Cons

• Built-Up Roofing: Water pooling, blistering, adds immense weight on a building, a bit more expensive than single-ply roofing
• Single-Ply Roofing: Seams are more vulnerable to leaks, more high-maintenance, UH exposure can deteriorate the adhesives, less durable compared to built-up roofing

Which Roofing System Is More Energy Efficient?

Single-ply roofing is arguably the more energy-efficient option because it does an excellent job of reflecting and retaining heat and helps keep energy consumption low in both cold and warm seasons.

Reduce your building’s energy costs with our single-ply roofing systems. Get your free assessment here.