Home & Garden Architecture

Do Flat Roofs Leak?


    • Flat roofs tend to have shorter life spans than sloped roofs since they get pounded by bad weather and often sit under the weight of a heavy snow or rainfall. Whether you've got a partial flat roof, such as over a garage or porch, or a full flat roof, finding and fixing the leak eliminates further damage down the road.

    Finding a Leak

    • You've got to look for leaks when flat roofs are dry, not wet. Often, flat roofs develop pools around a leak. If it rained recently, you might see small pools of water that help identify problem areas. Or you might see rings of dirt these pools left behind. Work your way around the roof, looking for small holes or cracks in the material. Check both the roof as well as the flashing and any seams for cracks and other areas in need of repair. If you find a trouble spot, test it with water. Run a hose on your roof, and direct the water near the problem area, using a low setting. Water takes up to 10 minutes to travel through a leak. Have someone inside your house watch the spot, or go inside yourself to confirm suspicions.

    Fixing a Leak

    • For a tar and gravel flat roof, you'll need more roofing tar and gravel for a patch job. Remove gravel from the leaky area. Apply roofing tar over the leaky area, using a trowel, adding tar until the area is level with the roof around it. Cover the tar with a piece of reinforcing mesh, then add more tar. Pour gravel on top. For a rubber roof, you'll need to cut a patch from rubber and seal it to the roof using rubber seam adhesive or a primer and seam tape. It can be tricky to find rubber roofing supplies, so you may prefer to hire someone.


    • If you've had roof problems for years, replacing the roof material can eliminate both the frustration and expense of chronic repair. Asphalt shingles don't work well on flat roofs, nor does a rolled asphalt product. Synthetic rubber or plastic single ply membranes offer leak protection and may come with up to a 20-year warranty. These membranes can be glued or fastened directly to a flat roof. If you want to upgrade your roof, find a professional roofer who can install the new finish for you.

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