Do Ice Dams Damage Your Flat Roof?

Icicles hanging from roof.

The winter freeze/thaw cycle is prime season for ice dams to form and damage your flat roof. The short answer to the question “Do ice dams damage your roof?” is yes, ice dams can damage a roof. But how?

In this post, we’ll cover the basics of flat roof ice dams and what you can do to identify and prevent them from causing severe problems.

What Are Ice Dams?

Ice dams are a natural barrier that form from the melting and freezing of snow and ice on a roof. They can form on nearly every type of roof but are particularly common on flat roofs. Ice dams prevent water from draining or exiting a roof, exacerbating leaks and problem areas.

How Can Ice Dams Damage a Flat Roof?

Pooling Water: Ice dams are the catalyst, the backup of water is what causes the real damage. The backed-up water and subsequently ice when it freezes can cause several types of damage.

Overload the Structure: Every building and roof has a load capacity; the extra weight may cause a collapse to occur. A gallon of water weighs 8.34 pounds, 1” of rain on a 1,000 square foot roof would be 620 gallons or 5,000 pounds of weight. Roofs are designed to shed water quickly for a reason, preventing them from doing so could lead to a roof collapse.

Worsen Existing Leaks or Form New Ones: The water will enter any crack or crevasse it can reach and at night when the temperatures drop below freezing the expanding ice can force those areas open even more, causing more cracks, amplifying existing leaks or forming new leaks.

Cracked Drain Bowls: Drains can quickly go from an afterthought to a major annoyance if cracked. Drains and drain bowls are usually made from plastic and if they’re backed up the ice can quickly split them, allowing a water entry area to begin forming. These types of entry will allow large amounts of water in during snow melts and summer thunderstorms.

Not to mention an icy roof presents a major safety concern for anyone that may be entering the area, whether that’s HVAC technicians or a building manager trying to find a leak.


Roof Leak due to ice damage.

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What Can I Do To Prevent Ice Dams?

If there’s no water on the roof to freeze then ice dams can’t form. Your goal is to prevent the back up of water on the roof and make sure its draining as intended. A dry roof is a happy roof!

A few ways you can do that is to:

  • Clear and clean roof drains
  • Address sags and low spots
  • Research and prepare de-icing chemicals
  • Insulate the roof
  • Install heating coils

Start with the roof drains. If they are blocked, make sure to clear the debris and leaves that may be blocking it. (This should normally be taken care of in the fall once the leaves have fallen) Address any ice by gently removing it to prevent the drain from cracking or thaw it out with a hair dryer.

Next, address the low spots. If there is debris in the low areas make sure to remove it. Unfortunately low spots must typically be resolved by getting a contractor to fill them in or level the surface. You can prevent ice from forming by using a broom to sweep the water towards the drains or blowing them out with a leaf blower after it rains or snows.

Stock some chemicals. You can usually apply de-icing chemicals or salt to roofing materials without fear of damaging them but be sure to check with the manufacturer or your roofing company before doing so. Failure to verify could lead to damage or a voided warranty.

Consider increasing the insulation. Specifically, adding insulation between the roof and inside of the building. The unequal distribution of heat rising to the top melts the ice, causing the water to move towards the dams and then refreeze. Preventing the heat from escaping and affecting the roof can stop the ice dams from forming in the first place. Options like interior spray foam or spray foam roofs create a very tight barrier that would also help bring your energy costs lower during the summer.

Install heating coils. If you continue to have issues, heating coils may be worth installing. You can have coils installed around all the drains and in any gutters to prevent ice dam build up and water back up.


I Have Ice Dams on My Roof. What Should I Do?

The best solution would be to remove them. If removing the ice dam is not an option, clearing a path for the water to get to the drains is the next best. By gently removing whatever parts around the ice dam you can, clear a path for the water to begin draining. It may be enough to prevent any serious issues but you should be checking on it every couple of days to make sure it has not begun building up again. While your checking for build up, continue to add de-icing chemicals and removing parts of the ice when possible. The goal is to eventually have it cleared off and water flowing normally.

At no point should you use any type of hammer or blunt force object to crack the ice. You should not hit or forcibly break the ice while trying to remove it. Most underlying substrates or roof materials become brittle and susceptible to damage when subjected to freezing temperatures.

Pictured below is damage sustained to a roof when someone used a hammer to break ice while searching for a leak.

An example of subtle roof damage.


To remove ice and ice dams by hand, gently try and slip your hand underneath the ice while lifting away from the roof.

If you decide to clear the ice dams yourself or just want to go check the roof, please exercise extreme caution while on it. Roofs are already dangerous enough without the added issue of ice. To prevent an accident from happening we would highly recommend choosing a reputable contractor to do the work for you.

Request a Roof Inspection

If you’re not sure if your roof has ice dams and just want to be sure it’s in good condition, let us know. Contact us to schedule a roof inspection.