How to Repair a Leak in the Roof Around PVC Pipe With Foam Gap Filler

Written by donna armstrong
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How to Repair a Leak in the Roof Around PVC Pipe With Foam Gap Filler
One can of foam filler can save a lot of money on caulk. (glazier image by Greg Pickens from

Polyurethane foam or foam gap filler is a tight celled foam that is use to close off cracks or gaps in roofs and walls. This foam is perfect for blocking holes to keep out insects, drafts and small animals. Most foam fillers can be used on wood, drywall, PVC, masonry and glass. One can of foam filler is equal to approximately 12 to 24 tubes of caulk.

Skill level:

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Things you need

  • Wet rag
  • Towel
  • Scrub brush
  • Soap
  • Gloves
  • Foam gap filler

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  1. 1

    Check the weather. Foam filler does not dry well on rainy days or days with high humidity. For optimum results, install the foam filler to a dry roof with at least an hour of low humidity and not rain.

  2. 2

    Clean the area around the PVC pipe paying close attention to the area that leaks. In most cases a wet rag will clean way most debris, however, a scrub brush and soap can be used to clean tough, caked on dirt or grime.

  3. 3

    Remove the cap on the can and insert the small plastic straw that is attached to the can. This straw is inserted where the foam sprays from. The straw allows you to inject the foam in small spaces and control the spray of the foam.

  4. 4

    Wear gloves to protect your hands. Most types of gloves will work. The main concern is to ensure the skin is covered. Polyurethane foam can cause rashes and chemical burns. Do not touch your face, eyes or mouth with the glove after it has been used to spray the foam.

  5. 5

    Shake the can of foam gap filler before using it. Normally five to 10 strong shakes does the trick.

  6. 6

    Place the spray straw in or as close as possible to the crack that is causing the leak and press down on the sprayer to dispense the foam. Pull back on the can about one-half an inch once the spray as started.

  7. 7

    Spray around the base of the PVC pipe and cover the area thoroughly. The foam will expand as you spray and you will be able to tell what has and has not been covered. Spray foam in any cracks around the area to ensure complete coverage.

  8. 8

    Allow the foam to dry. Most foam gap fillers will dry with in 30 minutes. Once the foam is dry it can be touched or trimmed to look more appealing. Check the label on the can to find out how long the foam takes to dry.

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