What Is the Most Common Type of Commercial Roof?

Why Are Most Commercial Roofs Flat?

What do you picture when you think of a commercial roof? There's a good chance you imagine a flat roof. While commercial roofs can also be pitched, it is more common to see flat or low-slope roofs on commercial buildings. This is the opposite of residential roofing, where you are more likely to see a pitched roof.

Most commercial roofs tend to be flat because flat roofs are often more cost-effective than pitched roofs when it comes to construction expenses. This is because of the size and scale of commercial buildings. Not only do pitched roofs require a more extensive roofing structure, but commercial facilities tend to be much larger and higher than residential roofs, making installing and maintaining a pitched roof more costly and more dangerous for maintenance and installation crews. Furthermore, a flat roof allows space for building systems (such as heating and cooling systems) to be installed, allowing businesses to maximize their interior space.

Other reasons commercial roofs are more likely to be flat than pictured include:

  • Flat roofs are more practical
  • Flat roofs allow for rooftop installation of HVAC systems, solar panels, electrical equipment, and other important systems
  • Flat roofs can be designed to provide more usable space for the building's tenants
  • Flat roofs are relatively easy to maintain for both professional roofers and building maintenance teams

The one area where flat roofs suffer compared to pitched roofs is in water drainage. While flat roofs are more prone to issues with leaks and moisture, commercial flat roofs tend to have extensive drainage systems designed to ensure that water is efficiently removed from the roof during rainstorms and other weather events. And, if properly maintained, a commercial flat roof is no more likely to have water problems than a pitched roof.

Types of Commercial Roofing Materials

Commercial roofs come in a wide variety of materials, all of which are designed to meet the specific building and/or business needs. Because commercial roofs tend to be much larger than residential roofs, they can be quite costly to replace. With this in mind, commercial roofing materials are designed to be durable, long-lasting, and cost-effective.

Some of the most common materials used in commercial roofing include:

  • Built-Up Roofing (BUR) membrane
  • Ethylene Propylene Diene Terpolymer (EPDM) membrane
  • Modified bitumen (MB) membrane
  • Metal
  • Polyurethane spray foam (SPF)
  • Polyvinyl chloride (PVC) membrane
  • Thermoplastic polyolefin (TPO) membrane

What Are Green Roofs?

Another type of commercial roof that is gaining in popularity across the US is the green roof. Green roofs (also called living roofs and eco-roofs) are those that incorporate plant life. They have become more common in urban areas where people are looking to increase available green space. Green roofs can also help improve a building's energy efficiency as they provide insulation for the roof and help remove and even prevent excessive heat buildup on the roof.

There are several different types of green roofs, and many are designed to be low-maintenance and to have low water requirements. It is also very common to see a green roof combined with a blue roof and feature storm and rainwater collection and other water conservation features.

Green roofs are still relatively uncommon in Arizona, but there has been increased interest and research into finding a way to make these new, environmentally friendly methods work in the Southwest.

How Long Do Flat Roofs Last?

Commercial roofs are designed to last for decades. On average, a flat commercial roof will last around 20-25 years. However, if installed using quality materials and well-maintained, a commercial flat roof may last up to 40 or 50 years. It is also worth noting that without proper maintenance, or when neglected, a flat roof may need replacing in as little as 10-15 years. The lifespan of a pitched commercial roof is roughly the same. Just as with a flat roof, the lifespan will depend on the type of roof installed, the quality of materials and installation, and whether or not it is well-maintained.

To learn more about commercial roofing or to discuss your options with an experienced roofer, reach out to Lyons Roofing, Inc. We are your go-to roofing expert, and we love helping our commercial customers get the most out of their roofs.