How to Fix Sweating Pipes

Updated: Jun. 30, 2017

A simple way to prevent condensation on cold water pipes in humid weather.

FH99JAU_SWEPIP_01-2Family Handyman
Cover cold water pipes with inexpensive foam pipe insulation to prevent condensation and dripping in humid weather.

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Photo 1: Install pipe insulation

Cut pipe insulation to length with a serrated bread knife.

Photo 1A: Miter corners at joints

Miter the corners and cut a V-shaped notch where pipes intersect at a “T.”

Photo 2: Tape the joints

Seal joints between lengths of tubing with special “peel-and-stick” seam-sealing tape or foil duct tape.

If your cold water pipes are sweating more than you are on these hot summer days, here’s the simple cure. Run down to the local home center, lumberyard or hardware store and pick up some foam pipe insulation. The deluxe version we purchased has a peel-and-stick seam along its length and costs about $3 for 6 ft. Less expensive insulation lacks this feature, but you can tape the seam to seal it. We also bought a roll of peel-and-stick seam sealer to wrap around the joints between tubes. The insulation is available in different sizes, so you’ll need to measure the diameter and total length of the pipes you intend to insulate.

The insulated tubing keeps the warm humid air from condensing on the cold pipes. Insulating hot water pipes offers little advantage beyond the possibility of getting hot water sooner at faucets far from the water heater.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Tape measure
  • Utility knife
You’ll also need a serrated bread knife.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Foam pipe insulation
  • Seam sealing tape