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Up on the Rooftop

Causes and Prevention of Commercial Roof Collapse

24 March 2020

Lori Silva

Flat commercial roofs are at risk for collapse. Although local codes are available to increase weight loads, there are many reasons why the weight on a flat roof can surpass the limits. The following are some reasons for collapse, along with the necessary tactics to avoid it.

Snow Load

Unlike on a pitched roof where the weight of the snow causes it to slide off, snow simply accumulates on a flat roof with nowhere to go. Ideally, your area will never experience more snow than the snow load limits for your roof, but that isn't something you can count on. Spring and fall snows, in particular, are an issue because they tend to be wet and heavy, compared to the dry, light snow of winter.

Fortunately, your commercial roofing contractor can help you with snow removal in the event of a record snowfall. It's better to have it done by a roofer that knows how to safely remove snow without damage, as opposed to your maintenance crew -- unless maintenance has been trained on rooftop snow removal.

Drain Clogs

Every flat roof contains drains. Smaller buildings may only have drains around the roof perimeter, whereas larger buildings may also have one or more drains in the middle of the roof. If these drains become clogged, then water can collect on the roof and cause weight issues. This is mainly a problem during heavy rainstorms where water collects faster than it can drain or evaporate.

Maintenance of the drains prevents problems. Have maintenance inspect the roof and clear debris, such as bird nests and fallen leaves, from the drains at least once a month. Your roofer can also install devices to prevent birds from being on the roof, as well as cages around drain openings to keep debris out.

Weight Creep

A flat roof is a very useful thing, particularly for commercial buildings that need a place to put items like HVAC systems well away from areas on the ground that could impact operations or customer traffic. Yet, over time the weight on the roof may creep upward. It might start with a newer, larger, and heavier HVAC system, and then it may be tempting to lease the space for a few communications towers and attenuate.

It can be quite easy to unwittingly surpass the weight load for your roof, but consulting with a roofer can help you prevent this issue. Whenever you are adding or altering any rooftop items, first consult with your roofer so you can make the wisest decision not just on what to add, but also on the best area of the roof to install the item.

Contact a commercial roofing service in your area for more assistance.

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