How to Waterproof Your Flat Roof in 5 Easy Steps

In almost any given temperate climate situation regardless of where you live, it’ll likely rain at some point—albeit to varying degrees.

Given this inevitability (aside from the more arid regions), and the specific type of roof you have, you would be best to assess whether yours needs to be waterproofed in the event of a torrential flooding (if you happen to live in a desert climate, for example).

Here are some easy steps you can follow to weather proof your flat roof in particular—one of the more popular roofing types.

Observe and inspect your roof

First off, you need to thoroughly inspect your roof before beginning the waterproofing process. On a positive note, if you find any leaks, that doesn’t necessarily mean you will have to replace the entire roof. However, the tricky part is identifying the core problem and coming up with a remedy in a timely manner.

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Bituminous waterproofing on a flat roof by W. Carter via Wikimedia Commons.

Before you begin, make sure to nail down (no pun intended) the fundamentals before addressing the leak(s). For starters, make sure your roof is sturdy and safe to walk on and secure enough to hoist your ladder against, too. We also recommend you to consider having someone at the base of the ladder to hold it while you’re climbing it.

Used reinforced bitumen membranes (RBM)

RBMs are some of the more popularly used materials to waterproof flat roofs. Typically, this involves using a few layers—two or three—across the entire surface area of the roof. These are then bonded by hot bitumen which is combined with polyester to effectuate a waterproof membrane.

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Bitumen on a paperboard flat roof by sanremo-domains via Pixabay.

At Rexoseal, we recommend embedding our 5” membrane on all joints with the 1000 multi-purpose sealant for best results. Next, embed a 40” wide membrane on the entire roof with the same product, too. Overlap this by another 3” before sealing all flashings, vents and drains with a 5” membrane.

Consider using a repair kit

These are most ideal for small areas of the roof that need to be fixed. These are most in alignment with those who are not experienced in undertaking DIY repairs on their roof because they can follow along according to the manufacturer’s instructions.

Home construction tools by Life of Pix via Stockvault.

However, you should note these are generally only used for roofs that are initially waterproofed, but damaged. With patch kits, for example, you can apply what is a sticky adhesive sticker to the damaged surface. 

Use a sealant

As mentioned in step three, you would be wise to double-check to make sure you’ve applied the correct sealant for your flat roof. This acts as a seamless and easy solution that is typically used for small surfaces, but it can also be used to cover entire rooftops, too.

Our Rexoseal 1000 rubberized waterproofing sealant.

But what’s perhaps more convenient about it is that literally anyone can do it. We recommend choosing between a sealant and liquid rubber if you’re trying to determine the longevity of your leak remediation.

Begin the drying process

Next, allow the sealant (if you went that route) to dry for two to three hours between coats, or when it is dry to the touch.

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A rubberflat roof by Crownbuild via Wikimedia Commons.

Now enjoy your new waterproofed home roof!

Once you are ready to get started on your own DIY project, make sure to check out our flat and low slope roofs DIY steps today.

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