How to Seal Water Leaks in a Fiberglass Roof

Updated February 21, 2017

No matter what type of roof you have, leaks are almost certain to occur at some point. Leaks can be large or small, but either way, they need to be fixed properly to keep the inside of the home in good shape. Fixing leaks on a fibreglass roof is similar to fixing leaks on any other type of roof. The most important step to properly sealing a fibreglass roof that is leaking is finding the leaks. When this is accomplished, the rest of the job is manageable for many homeowners.

Find all the leaks on the inside of the house to determine how many and where they are on the outside. Go up into the attic where the leaks are entering the house and locate precisely where they are coming in. Look for stains on the underlayment of the roofing to determine where the leaks are entering the house.

Climb a ladder and inspect the roof looking for any damage or cracks in the roof. Get on your hands and knees and go over the roof inch by inch with your hands beginning in either corner and working all the way around. Look for areas that match where the leaks were located on the inside of the house.

Clean all the damaged cracks and gaps by pouring water on a rag and scrubbing any excess dirt and debris that may be located in the cracks. Pour dish soap on the rag and clean the areas thoroughly. Rinse, and dry them with a clean rag.

Spread a bead of DAP watertight roof sealant caulk over the first crack and continue on by filling all of the cracks on the roof. Spread roof patch over the bigger cracks and holes with a trowel.

Allow the caulking and cement ample time to dry and inspect the area to make sure all the gaps, holes and cracks have been properly sealed.


Be cautious when working on a roof with a ladder.

Things You'll Need

  • DAP roof caulking sealant
  • Ladder
  • Caulk gun
  • Water
  • Rags
  • Dish soap
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About the Author

Alexander Callos began writing in 2005 for "The Lantern" at The Ohio State University and has written for various websites, including Bleacher Report, Top Ten Real Estate Deals and Columbus Sports. He has published articles for CBS Sports, and other websites. He graduated in 2007 from The Ohio State University with a bachelor's degree in public affairs journalism.