Flat Roof Snow Buildup: How to Handle It Like a Pro

Flat roofs are popular in homes and commercial buildings for being efficient, low-maintenance and stylish. They’re easier to install than other roofing types. However, they have a reputation for cracks and leaks when exposed to external elements like changing weather. Heavy snowfall and ice pose added challenges for your roofing that need to be dealt with promptly to prevent damage to your building. With proper planning and maintenance, you can keep yourself and your property safe through the winter. Following are the different ways your property can be affected by snow and what you should do about it.

How a Flat Roof Can be Affected by Snow

Although flat roofs offer many advantages, they may suffer during the winter months. Here’s what you need to look out for.

  • Bowing and Ponding

Snow and/or heavy rain can accumulate on your flat roof with no outlet for runoff. This can place unnecessary pressure on your building’s structure. Additionally, the slow and steady pace of snowfall, along with its texture, allows it to gather in large quantities. It can’t, like rain, run off once a large quantity has collected, and it won’t bounce off like hail. The weight of snow is what results in roofs bowing under pressure, and when snow melts, it leads to further ponding water.

  • Freeze-Thaw Cycle

The most important thing you need to understand about this term is that water expands as it freezes. When snow starts to melt, water can make its way into cracks on your flat roof. This can damage your building’s structural integrity so should be taken care of promptly.

  • Leaks

Ponding water and the freeze-thaw cycle can lead to leaks on your flat roof. Although they’re problems that occur gradually, they’re difficult to detect and can result in costly damage. In worst-case scenarios, it can lead to roof collapse.

How to Protect Your Flat Roof Against Snow Damage

Since flat roofs are susceptible to leaks because of snow, let’s examine what you can do to ensure it doesn’t lead to property damage.

  1. Annual Inspections

Having your roof inspected by a professional roofer is the best way to avoid problems or prevent existing ones from becoming bigger. When you’re looking for a roofing company, make sure they have a good safety record, insurance and great reviews from past clients. A certified roofer will be able to look for damage and tears to your roofing membrane, check its overall integrity and make sure drainage outlets are working properly. Ideally, you should have your roof inspected at least once a year to keep it in good shape.

  1. Waterproofing

Waterproofing your roof is vital to protecting your property from water damage. There are waterproofing membranes available that act as a watertight sheet and typically last anywhere between 20 and 30 years. If you’ve recently moved into a property, find out from the builder or seller when the waterproof membrane was installed or replaced. If it’s been quite a while, you should make sure it’s looked at closely when having your roof inspected.

  1. Insulation

Buildings with flat roofs don’t typically have the same kind of attic space you see on buildings with sloped roofs. In the absence of that space, building heat can warm up the roof, causing standing snow to melt. The resulting water can work its way towards the edges, which aren’t warm, and re-freeze it, forming ice dams. This can be avoided with proper insulation, as it prevents inside heat from warming the roof. You can insulate your roof by:

  • Adding a layer of rigid foam insulation to the underside of the roof;
  • Choosing fiberglass insulation;
  • Using a heated de-icing cable to melt the ice.


  1. Drainage Outlets

Flat roofs are susceptible to collecting debris such as leaves and twigs. These can get blown into and block your drains, preventing them from efficiently eliminating water. This can result in leaks appearing when melted snow doesn’t have anywhere to go. So, before the peak winter season hits, you should make it a point to have your entire roof swept clean.

Steps to Take if You’re Concerned About Your Roof

Now that you’re aware of how snow affects flat roofs and how to shield it, the next step is working out whether you should repair or replace it. It’s generally more cost-effective to replace than repair old roofing. Chances are you’ll end up spending more in the future by constantly repairing a roof that isn’t offering optimal efficiency. By selecting a quality product and having it installed by professionals, you protect your building for years to come.

Even though you may have taken care of your roofing in the past, it will need special attention to ensure it protects your building (and you) through the winter. Maintaining your flat roof’s integrity requires effort and is a year-round job. With these tips you’ll hopefully be able to take preventative measures to make sure your flat roof handles the stress that winter weather brings with it.

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