How to Repair a Leak With a Foam Gap Filler

Updated July 20, 2017

Leaky plumbing pipes are a major source of inconvenience, increased water bills and household damage. Pipe repairs are often costly and time consuming, but there is a way to repair leaks without replacing the pipes. Foam gap filler is an expanding foam product that, when sprayed over the leak in a pipe, fills the gap and stops the flow of water. This project depends on access to the leaky pipe but takes only a few hours to complete. Foam gap filler is available at most home improvement or hardware stores.

Disconnect the flow of water to the leaking pipe. This is usually at a water manifold, individual pipe control valve or the main water supply.

Allow any heavy leakage to subside now that the water is off. Dry the pipe completely with a cloth to examine the leak source closely. Clean the pipe around the leak with a bowl of warm soapy water. Use a degreaser and sponge if there is any greasy or sticky build-up.

Position the can of foam gap filler at the point of the leak and spray around the circumference of the pipe with as smooth and steady a stroke as possible. As the filler expands, it should cover the entire leak. Filling the area around the pipe strengthens the bond with the surface to reduce the risk of the leak reoccurring.

Trim excess filler from the pipe with a sharp utility knife if the material expanded too much or in an unsightly way.

Leave the filler to dry. Although the material hardens on the exterior in seconds, it takes a few hours to fully solidify and cure.

Turn the water flow back on. Check the filler for stability and evidence of any further leaking. Inspect the pipe repeatedly for the first few hours and then periodically for a few days. Repeat the process if leaks continue.


If the filler can comes with a directional tip for application, place it directly over the leak to get the foam at the source.


Keep the gap filler away from any sources of combustion; it is highly flammable.

Things You'll Need

  • Cloth
  • Bowl
  • Liquid soap
  • Degreaser
  • Sponge
  • Utility knife
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About the Author

Julie Keyes has been a writer for over five years. She has written marketing content for the Michigan division of a large international company and also provides freelance writing assistance to personal clients who require a particular type of marketing message. Keyes holds a degree in sonography from Jackson Community College.