How do I Waterproof a Roof? (with pictures)

T. Webster
T. Webster
Silicone sealant, which can be used to repair leaks.
Silicone sealant, which can be used to repair leaks.

Waterproofing a roof typically entails using a liquid sealant that is designed to repair leaks or to seal an entire roof. The techniques and materials used to waterproof a roof vary depending on the kind of roof you have and the nature of the repairs you need to make. In fact, the first step is to assess the extent of any needed repairs.

A novice can generally fix small problem areas or perform the routine maintenance needed to waterproof a roof. Keep in might that it might be necessary to waterproof an entire roof if it is leaking and the source cannot be located. If the job seems complicated or the roof is in need of serious repair, consider enlisting the help of a professional.

A ladder is needed to reach the roof.
A ladder is needed to reach the roof.

To waterproof a roof with tar shingle, check for ripped or warped shingles that might be allowing water to seep through. A caulking gun filled with silicone sealant usually will work in repairing leaks related to these kinds of problems. If the roof has a chimney, check around it to look for areas that might allow water to get in. Use the sealant to repair any problem areas.

Poured concrete roofs require a waterproof coating that seals the concrete to help prevent it from shifting or dissolving. This can be a major problem in areas that have freezing temperatures in the winter followed by a lot of rain in the spring. Weather extremes can cause the concrete to crack, allowing water to seep through.

The appropriate coating for a concrete roof is one that provides a rubbery or plastic-like coating. These coatings will shift and expand with the concrete. They also provide a watertight seal to prevent the roof from leaking. Be sure to look for products made specifically for concrete roofs and carefully follow all instructions.

Be aware there are pros and cons if you decide to waterproof a roof on your own. Much of this depends on your skill level and experience. The advantages include increasing your home repair skills, saving money and understanding how to do waterproofing should any leaks spring up in the future.

If you do the repairs incorrectly, however, you probably will spend even more money to hire a contractor who can correct the job. There also is a chance that you will damage the roof or injure yourself. Remember to allow yourself ample time to complete the project, and always put safety first. Use a strong, sturdy ladder or scaffolding, and make sure to wear foot gear that will prevent you from slipping while on the roof.

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Discussion Comments


A good place to start your search when you have a leak is around any fixtures on top of the roof. The article mentions chimneys can be a problem, so can any other spot where there is any type of opening to the house.

Sometimes rain can blow into openings on the side of your house like attic vents. Water can also get under loose pieces of siding and soak through wood.


Like the article says, finding the spot where water is getting under your roof can be time consuming and virtually impossible to do unless you search during a rain storm. Unless the cause is obvious, you're probably not going to locate the defective area by walking around on the top of your house.

My advice is to go to the attic and see where the water is entering the house. Maybe you can find the leak there, but even when you find the water coming in, you may not be able to locate the exact spots where it is coming through your shingles on the roof.

As this article says, you may have to call a professional who has more experience with these situations. He can find the leak and you can watch him so you will know how to waterproof a roof in the future.


Our leaking roof has been the only real headache we have had since we bought our house. The house is old and needs some repairs. We knew this when we bought it.

At first we had one leak in the mud room. There is a venting pipe on the roof above that section of the house, so I bought some sealant and sprayed it around the vent pipe. After several rains and no more leaking, we thought the sealant had done the job.

However, the leak has since returned and there are a couple other places, but they don't leak every time it rains. When I go on the roof I can't tell where the problem is. The shingles look good. I'm still searching, but this is really becoming one big headache. I know the leaks can eventually cause some serious damages.

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    • Silicone sealant, which can be used to repair leaks.
      Silicone sealant, which can be used to repair leaks.
    • A ladder is needed to reach the roof.
      A ladder is needed to reach the roof.