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October 16, 2018

Flat Roof Facts to Keep in Mind

Although some commercial buildings have steep-sloped roofs that are shingled, most commercial facilities are flat. They may have an exposed structural metal deck or be covered with single-ply membranes or built-up systems.

commercial flat roofing system

Here are a few flat-roof facts:


It takes less material and therefore cost to construct a flat roof than a sloped roof, which is why most (especially larger) commercial facilities are flat. However, even “flat” roofs need to have some slope built in to allow for water to drain.

Water Drainage

Obviously, steep-sloped, shingled roofs shed water and snow readily. Flat roofs should be constructed with a slight slope to promote positive water flow toward interior drains or exterior gutters and downspouts. However, over time, roofs can settle, and create areas where water “ponds” and doesn’t drain. You should regularly inspect your roof to ensure that water is moving as it should.

Winter Weather

Obviously, flat roofs can accumulate a lot of snow, as wintry precipitation does not just slide off the roof like it does with a sloped roof. Buildings are typically constructed to handle the weight load of snow and ponding water. However, abnormally heavy snowfalls may cause structural problems and you should have a rooftop snow removal plan in place for those situations.

Summer Weather

A flat roof usually has a lot of surface area exposed to the sun. A focus on reducing building energy consumption over the past couple decades has created a market where white, highly reflective roofing systems are predominantly installed on commercial facilities. Reflective roofing can save building owners significantly on their cooling costs during hot months.

Multiple Purposes

In addition to protecting a building from the elements, a flat roof is a location for storage and installing equipment such as satellite dishes and HVAC units. Obviously, the building and roof structure should accommodate those loads. In addition, if there’s a membrane on the roof deck, it should be protected from foot traffic – with walk pads, for example – from workers that need access to that equipment.

Roof Age and Maintenance

There are many factors that determine how long a flat roof will last once it’s installed, including the roof material, climate, number of penetrations, foot traffic and, perhaps most importantly, the initial quality of the installation. All roofs require some level of inspection and maintenance to make sure that they are providing watertight protection.

If your roof is not performing as it should or it’s beginning to show signs of age, we would welcome the opportunity to discuss replacement options with you.

Article by Royalty /


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