How to Seal Gaps Around Pipes and Wall Holes

Gaps around pipes, cables and air conditioner lines are some of the most common sources of drafts in a home. You can seal most of them yourself in a few minutes. Find the gap, clean it, and fill it with a sealer that suits its size and location.

Where to look for gaps

• Under the kitchen and bathroom sink, where water and drain pipes go into the wall
• Around air conditioner lines and outdoor faucets
• Behind the washing machine and dryer
• Where cable and internet lines come through the wall
• Around radiator pipes and in cabinet backs

How to find drafts

1. Feel for air. On a windy or cold day, move a slightly damp hand slowly around pipes and openings. You'll feel cool air where there's a gap.
2. Use a light. At night, shine a flashlight from one side of a wall opening while someone looks from the other side.
3. Look for clues. Dust lines, cobwebs and small insects near a pipe usually mean air is getting through.

Choose the right sealer

• Small gaps around pipes and cables: a moldable sealing clay or putty. It presses in by hand and stays flexible, so it's easy to remove later.
• Thin cracks along edges: a flexible caulk.
• Larger holes: expanding foam, then trim it flat once it's dry.
• Pipes that get hot: check the product is suitable for the temperature, or ask a professional.

How to seal a gap around a pipe, step by step

1. Clean the area. Wipe away dust and grease so the sealer can grip the surface. Let it dry.
2. Soften the clay. If you're using sealing clay, knead it in your hands for a minute until it's soft and easy to shape.
3. Press it in. Push the clay firmly into the gap all the way around the pipe. Work it into corners with your thumb.
4. Smooth the edges. Run a damp finger along the edges for a neat finish.
5. Check again. Repeat the hand test. If you still feel air, add a little more.

Common mistakes

• Sealing over dirt or moisture. The sealer won't stick well and may come loose.
• Using the wrong product for the gap size. Clay is great for small openings; big holes need foam or a patch.
• Blocking ventilation. Don't seal vents, dryer exhausts or gaps that are meant to let air out.
• Ignoring leaks. If a pipe is wet or dripping, fix the leak first. Sealing it hides a bigger problem.

Why it's worth doing

Sealing small gaps helps keep rooms more comfortable, cuts down on dust, and removes an easy way in for insects. It's one of the cheapest home fixes you can do in an afternoon.

Our Moldable Gap & Hole Sealing Clay presses into place by hand, no tools needed, and is made for wall holes, air conditioner pipes and sewer pipe gaps. See more home fixes in Home & Kitchen.

FAQ

Can I seal gaps around pipes myself?

Yes, for small gaps around water, drain, cable and air conditioner lines. For gas lines, electrical panels or large holes, call a professional.

Is sealing clay permanent?

Moldable clay stays flexible, so you can remove or reshape it later. That makes it handy for pipes you may need to access again.

Will sealing gaps keep bugs out?

It removes one of the easiest ways in. Combine it with door sweeps and window screens for the best result.

How do I know if a gap is too big for clay?

If you can fit more than a finger into it, use expanding foam or a patch first, then finish the edges with clay or caulk.

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