Roof Types: The Best Roofing Products for Your Commercial Building

If you’re in the midst of a commercial building project, you’ll probably be wondering about what type of roof is better. Are flat roofs a better option for commercial buildings? Should you choose a steep slope roof instead? To help you understand the pros and cons of each, here’s everything you should know.

Roof pitch determines the material best for a commercial roofing project

The pitch of a roof is the angle (steepness) of the roof. In general, when building a commercial structure, you’ll have two large roof types depending on the pitch: low-slope or steep-slope.

Depending on the area, size of the building and overall design, one type of roof will be a better option. Here are the basics.

Low-slope roof: everything you need to know

Low-slope roofs are those where the pitch is below 2:12. In layman terms, this means that your roof is less than 2 vertical units (usually, inches) for every 12 horizontal units. Because of the very low pitch, sometimes people refer to these as “flat roofs”. In fact, low-slope roofs aren’t flat at all: any roof needs a slope to guarantee drainage.

Because the angle of the roof is small, low-slope roofs have a watertight membrane to keep the structure safe. This roof type cannot be covered in shingles, since they need an angle to allow water to drain properly.

Best for: Flat- or low-slope roofs are common in large buildings such as big box shops, schools, shopping centers and warehouses. The flatter surface makes maintenance and repair easier and faster than steep-slope roofs.

Types of low-slope roofs for commercial buildings

• TPO roofs: This roof membrane is made with a mix of rubber and plastic polymers, sealing your roof and fully waterproofing the entire surface. Because it usually handles light foot traffic well, it’s a great option for buildings that need constant access to the roof.

• PVC roofs: PVC is a single-ply plastic applied to low-slope roofs to create a waterproof barrier. It has a lower percentage of oil and petroleum than TPO or EPDM. PVC roofs are installed by welding the seams with heat, which allows for a bit of wiggle room during the expansion and contraction of the building.

• EPDM roofs: A favorite because of its low cost, EPDM is also made of polymer (AKA plastic). This material comes in very large sheets, which makes installation faster and less labor-intensive, without compromising effectiveness.

• Built up roofing (BUR) systems: A classic roofing solution for low-slope building, this roof type is made of multiple layers of ply sheets and asphalt. The multilayer system provides a high resistance to weather and light resistance to foot traffic.

• Modified Bitumen Roofing: This is a newer version of built-up roofing systems, and nowadays it’s one of the most used options for low-slope roofs. By combining asphalt with polymerized rubber/plastic, this creates a strong waterproof membrane that is lighter than the traditional BUR.

Steep-slope roofs

This roof type is more common in residential buildings. Any roof with a slope higher than 2:12 is considered steep-slope.

The steeper angle allows for water to easily slide down the building, but also makes maintenance a bit more invested since walking on the roof is more difficult.

In areas with harsh winters, steep-slope roofs allow for less snow and ice build-up, minimizing winter upkeep. On the flip side, this roof type isn’t very practical or cost-effective for larger commercial buildings.

Best for: Smaller commercial buildings designed to replicate the look of residential homes. These include churches, restaurants, apartment buildings, and buildings repurposed for professional services.

Types of steep-slope roofs for commercial buildings

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