DIY: Flat Roof Repairs

Updated July 20, 2017

Flat roofs are plagued with problems because water has a tendency to collect on them. Without a steep enough slope, rainwater and snow cannot run off, so it stays put and puddles. These roof puddles become stagnant and can cause roof damage. Flat roofs on houses are often made of multiple layers that protect the house's structure from being penetrated by the puddling water. If large bubbles start to form on your flat roof and you hear a sucking sound when you walk around on it, then you may want to consult a professional. However, repairing tears and holes in a flat roof is a moderately simple project.

Remove any surface gravel from the damaged area with a spade.

Cut a rectangle around the damaged area with a utility knife. Remove the damaged section.

Apply a thick layer of roofing cement to the inside of the rectangle with a putty knife.

Apply a rectangular patch of the same roofing material as the existing area or fibreglass mesh cut to size with scissors on top of the roofing cement. Press the patch down into the roofing cement to secure it.

Spread roofing cement over the patch with a mason's trowel. Re-cover the area with surface gravel.


Make sure the damaged roof is sturdy before you work on it. Use caution when working on roofs and ladders.

Things You'll Need

  • Spade
  • Utility knife
  • Roofing cement
  • Putty knife
  • Roofing material or fibreglass mesh
  • Scissors
  • Mason's trowel
  • Surface gravel
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About the Author

Rachelle Proulx has been writing since 2000. She co-owns a pet-sitting company, providing her the experience to cover pet care and small business. Proulx is also a flooring specialist who writes about flooring options, preparation, application and maintenance.