3 Types of Flat Roofs

While they’re more common on commercial buildings and Eichler style homes, flat roofs are a popular roofing option for residential homes throughout the San Francisco, Bay Area. They’re durable, versatile, and more energy-efficient. 

When it comes to flat roofs, there are a few varieties. Whether you’re looking to install a new flat roof or replace an existing one, understanding the different options can help you make the best choice. 

Built-Up Roof (BUR)

Also called a “tar and gravel” roof, the built-up roof (BUR) has been a mainstay in roofing for more than 100 years. As the name suggests, installers build the roof up, applying three to four layers of waterproof material and hot tar before packing down a layer of gravel or aggregate. 

While built-up roofs are affordable and easy to maintain, they do have a few drawbacks:

  • They’re heavy.
  • They don’t typically hold up well in adverse weather.
  • They’re one of the least energy-efficient flat roofing options.
  • Pinpointing leaks that develop can be a challenge as water can move laterally between the layers. 

Adding spray foam (SPF) roofing over a built-up roof can help increase the energy efficiency of your building or home. It also adds a layer of water protection. Even if a crack develops in the foam, water can’t go anywhere. It just sits in place until it evaporates. 

Modified Bitumen Roof

A modified bitumen roof is along the same lines as a BUR. The process involves unrolling single-ply sheets of rubber-based or plastic-based material and layering them (building them up) to create a more durable roof. 

While more expensive than a BUR, a modified bitumen roof is more flexible and energy-efficient. However, it’s more susceptible to tearing. The rolled on sheets also leave seams, which could result in leaks. 

You can address leak concerns by installing spray foam roofing. The spray-applied material dries into a solid, seamless blanket, covering the seams of your modified bitumen roof. It requires fewer inspections and less maintenance than modified bitumen alone, too.  

Rubber Membrane Roof

Also known as an EPDM (ethylene propylene diene terpolymer) roof, a rubber membrane roof is a popular flat roofing option. It’s a single-ply membrane engineered to resist damage from the sun. The material is lightweight and easy to install or repair. 

Rubber membrane roofs come in two colors — black and white. The former (which is more common) absorbs heat, which can increase your San Francisco cooling costs. The latter, however, adds more to your total cost. Both options are more vulnerable to punctures and other damage. You can avoid these concerns with SPF roofing. 

An Alternative Flat Roof Solution: Spray Foam Roofing San Francisco

Choosing a flat roof for your commercial building or home shouldn’t be overwhelming. Understanding the differences between your options is a great place to start. Weighing the pros and cons, comparing installation costs, and looking at longevity can all help you make a more informed decision. 

Spray foam roofing in San Francisco offers you a unique alternative. The liquid-turned-solid creates a solid, seamless closed cell coating over your entire roof, reducing the risk of leaks. It’s durable, UV-resistant, and incredibly energy-efficient. Properly cared for, it can last 50 years, much longer than other flat roofing options. 

If you’re interested in learning more about spray foam insulation for your San Francisco commercial building or home, American Foam Experts is here to help. Contact us for your free quote today!