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How to repair a leaky flat roof

September 14, 2019

A leaky flat roof can be an uncomfortable situation. It can be a tough prospect to live in a home with a leaky roof. This exposes you to the elements and leaves you vulnerable in your own home.

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To fix a leaky flat roof, it’s very important to know and be familiar with the kind of roofing that exist out there, and the kind that covers your home. Here are the various familiar types of flat roofs used by homes in Canada.

  • Spray Polyurethane Foam Roof
  • Modified Bitumen Roofing
  • Thermoplastic membranes PVC or TPO
  • Bur or Build up Roofs
  • EPDM Rubber Roof

It is completely normal for your roof to develop a leak. It is important to understand this if you want to learn how to fix a flat roof. Over time and with consistent exposure to the elements, your roof integrity will weaken, leading to the development of leaks. To that end, this article contains information on fixing leaky flat roofs. We will also help you understand why your roof may develop a leak.

Related article: Flat Roof Repair Is Key To Making Your Commercial Property Last


Why is your flat roof leaky?

Have you ever really thought about why flat roofs leak? There are a number of reasons why your roof may develop a leak. These reasons will be discussed in this section. The first reason why your flat roof may become leaky is water. Since your roof is a flat roof, it will always face difficulty dealing with water flow. This causes stagnation of water on your roof. This, in turn, leads to the roof absorbing the water and leaks on the other side of the roof.

Damages in the materials used for the flat roof construction is another reason why leaks spring up. Over time, materials used for flat roof roofing get weak and lose structural integrity caused by exposure to direct sunlight and harsh weather conditions. Wear and tear also occur which increases the chances for a roof leak. Sometimes, due to the structural build of a flat roof, it can sustain cracks and openings. These cracks cause extensive and long-time pressure on the roof. 

Also, we have flat roofs that have installations such as pipes, vents, chimney, and other equipment. These materials can create chances for roof leaks because they add to the pressure supported by the structure.

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How to fix your leaky flat roof? 

It’s very obvious that the very first step to getting a leaky flat roof repaired is locating where the leak is. How do you locate where your flat roof is leaky? All you have to do is locate the leaks inside and then trace the spot outside your home. This may require a ladder. Before we proceed far, it’s very important to note that you need to be careful when climbing a roof because of the height and the use of a ladder. 

If you are not confident about climbing heights, it’s recommended that you contact an expert at flat roof leak repair. Our roofing experts are always on hand to help you. Also, it’s important to note that solutions to a flat roof leak vary and are quite different based on the different types of flat roofs.

Concrete flat roof

With roofs like this, damages such as cracks are always prevalent. You need to apply a thin bitumen primer preceded by applying a bitumen based paint. This will have an effect of creating a sealant layer on the cracked portion.

EDPM Rubber roof

In this case, applying a lap sealant will be needed to fix small tears and holes on the flat roof leak portion.

Asphalt Flat Roof

This type of flat roof leak repair can be fixed by placing a small patch of roofing felt torched on the leaking part.

Felt Flat Roof

In cases like this,  if the old layer of the felt roofing can still serve its purpose well, a liquid system repair can be used. If you have an older layer of felt roofing, a patch of torched on roofing with an added layer will fix the leak.

Fibreglass Flat Roof

Leaks, in this case, can be caused by cracks and splits near board joints, upstands and trims which are caused by GRP flashes, contraction and expansion. Repairs can be done by cleaning the affected parts with soapy warm water. Also, acrylic sealant can be applied over and around the holes and cracks and then fortified by scrim plasterers.


The solutions listed above can help you fix your leaky roofs. However, we understand that these steps may be difficult if you are not technically inclined. Thankfully, our professionals can help you take care of your leaky roofs. Call us today!

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