flat roof waterproofing methods

How to Waterproof Flat Roofs Effectively

how to waterproof flat roof

how to waterproof flat roof

Having a flat roof has several benefits.

Apart from how easily accessible it is, the process of maintaining it is quite economical when compared with the pitched roof.

However, the pitched roof tends to be more long-lasting when it comes to durability. This is why you need to efficiently maintain your flat roof at all times to ensure that it serves you well for many decades more than expected.

One of the major downsides of having a flat roof is pooling, especially if the roof has an inadequate slope and drainage system.

If your roof is not properly waterproofed, there are great chances that you will experience leakages among other damages that can be detrimental to your building. This is why you need to learn how to waterproof your flat roof efficiently.

We shall be letting you know the various problems that could arise if your flat roof is not waterproofed and how you can adequately waterproof it to prevent such problems.


Damages/Problems that Could Occur to Your Flat Roof If Not Waterproofed

how to waterproof flat roof

UV rays degradation and alligatoring

A flat roof without waterproof or with poor waterproofing is susceptible to suffer from UV rays degradation and alligatoring.

The process by which debris, impact damage, water, and sunlight cause damages to your roof membrane and create alligator hide-like cracks is known as alligatoring. If this kind of damage is not repaired on time, it could become worse and cause your roof to develop cracks or start leaking.

Therefore, you need to thoroughly waterproof your roof with a good waterproofing solution to curtail the damages that UV rays degradation and alligatoring might cause to your roof and building in general.



This is another major problem you’d experience with your flat roof if it's not efficiently waterproofed. When your roof pools water, it indicates a poor drainage system or slope, which can’t remove water off the roof. And when this happens, your roof membrane could begin to get weak. This might eventually lead to serious damages or problems to your building.


An abode for insects/mosquitoes

Since pooling causes stagnant water, it creates an abode for insects like mosquitoes to thrive. This could cause diseases and sicknesses that are very detrimental to health.


Benefits of Waterproofing Your Flat Roof

Provides convenience and comfort

Waterproofing your flat roof is very convenient because it doesn't consume much time and is a very organized and less disruptive way to maintain or repair your roof.

Unlike the noise and disturbance that comes with changing or repairing a pitched roof, especially those made of aluminum or zinc, flat roofs don’t disturb the environment or entire neighborhood because they are faster, neater, and easier to work with.



The procedure helps you to save a lot of money. You get to save more than what is required for you to replace the entire roof. Also, it makes your roof last longer and prevents it from experiencing any form of degradation.

You won't need to bother about making repairs every year if your roof is properly waterproofed. All you need is to inspect your roof from time to time to ensure that everything is intact.


Product warranty

You’re going to experience peace of mind as a result of the benefits that many waterproofing products offer. Some products come with 10 to 30 years of manufacturer's warranty, which will give you the assurance you need when looking for quality waterproofing products.


Energy Efficiency

You tend to preserve the energy efficiency of your building when your roof is properly waterproofed. This is possible since water cannot stay on the roof anymore.


Tips to Waterproof Your Flat Roof Successfully

flat roof waterproofing methods

The waterproofing method or material you use for your flat roof building usually depends on the size of your building and the type of material that was used to build the roof.

Below are the tips that you must use to successfully waterproof your flat roof.


Inspect the roof

Before you start anything on your roof, thoroughly inspect it to be sure of where the problem lies. You might not know the level of damage that has been caused if you don't inspect it.

A good inspection will enable you to determine if your roof only needs waterproofing or a total change. However, you must make sure that your roof is safe to access when you decide to climb it. Seek the service of a professional to help you handle it if you’re not sure of how safe it is.


Consult an expert

Even though some waterproofing processes are DIY-friendly, others are arduous and might require the service of a professional. It is better to avoid making costly mistakes by calling an expert, especially if you don't have any idea or knowledge about how to waterproof flat roofs.


Get the right tools and materials

If you’re familiar with flat roof waterproofing and can do it yourself, then you need to ensure that you get the right materials and tools in place. The materials you'll need depend on the type of roof you have.


How to Efficiently Waterproof Your Flat Roof

There are 4 major materials you can choose from; they are listed below alongside their application procedures.  


1. Sealant

how to waterproof flat roof

Image credit: constructionreviewonline.com

This is usually for quick fixes and smaller roof surfaces, even though you can equally use it to waterproof an entire surface. It is a simple and DIY-friendly solution.

Sealants can be used for different types of roofs, ranging from bitumen to asphalt surfaces. They create durable and thick waterproofing layers and non-slip surfaces. All you need to do is to apply the sealant to the affected area to seal the cracks or damages.

If you’re waterproofing the entire roof, you can begin the application from the edges of the roof until every part is coated.


2. Repair kit/Patch kit

liquid waterproofing for flat roofs

Image credit: rvautoparts.com

Just like the sealants, repair kits are solutions meant for small areas that require quick fixes. They are, however, only meant for roofs that have been waterproofed but only require little repairs or rejuvenation. Therefore, repair kits are not ideal for new waterproofing projects.

They come in liquid solutions and patch or adhesive solutions.

You need to ensure that the surface is clean when applying the liquid solution, then you can consider adding a primer if necessary. Proceed to evenly apply the solution to the affected area by using a brush or roller. Then, allow the surface to dry and check it to be sure that it doesn't require any additional application.

For the patch solution, you only need to remove the backing from the patch and gently apply it to the cleaned surface of the affected area. Ensure that the application is very smooth and devoid of creases. Use your roller to gently press the patch to the surface for a firmer adhesion.


3. Reinforced Bitumen Membranes (RBM)

how to waterproof flat roof

Image credit: hacroofing.co.uk

Here’s the most in-demand and commonly used material by many residential and commercial buildings. Its application process is not DIY-friendly as that of sealants and repair kits. This is why it’s best to hire a professional if you intend to use RBM.

The application process of this material requires the addition of two or three layers of materials on each other across the whole roof surface. Hot bitumen is then used to bond the materials together. A waterproof membrane is eventually created when polyester is added.

The application process of the membrane may involve self-adhesive, pouring and rolling, cold adhesive, and torching.


4. Liquid Rubber

flat roof waterproofing methods

Image credit: cohe.co.nz

If you find RBM difficult to work with, liquid rubber is a great alternative. This type of material is ideal for any DIYer and can be used for both small and large areas.

Unlike sealants and repair kits, liquid rubber is not meant for quick fixes. It is a good waterproofing solution for new buildings that require waterproofing from the scratch.

Some products may require you to add primer to the roof before coating while others may not. You simply need to apply a generous amount of liquid rubber solution on the surface of your roof and spread it evenly to ensure that it’s well-distributed. After that, allow it to dry.

The result of such applications will be a durable and efficiently waterproofed flat roof that will stand the test of time.



Apart from your home's environment or exterior, the roof also helps to indicate how much you take good care of your home. Using a flat roofing system makes it even more apparent due to the less slope it has when compared with the pitched roof.

Therefore, regular maintenance of your flat roof will not only guarantee a neater and healthier abode to live in but will also make your roof last longer. And waterproofing is one of the best ways to have a durable roof for your home.

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Basavaraj Hanchinal

Basavaraj Hanchinal

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