Cold Water Pipe Condensation

Insulate the pipes from condensation using foam insulation sleeves to protect your home from damage to floors, belongings and storage in the summer months. Sweating plumbing is from the cold pipe of water condensing the warm humid air, to drip down on my stuff. This is an easy solution to several problems, like if you insulate your hot water pipes, too.

This time of year creates the perfect storm for dripping pipes in the basement ceiling. The humidity is high, the incoming water is very cold and the basement is warming up.

Warm moist air forms condensation whenever it encounters a cold surface. You will see it around a refrigerator door where the seal is bad, on a toilet tank and of course on the cold water pipes in the basement ceiling.

The water drips will leave a trail on the basement floor with dots of stain or mold on the carpeting directly beneath the cold water lines.

This does not happen under the hot water lines because they are not cold enough to cause condensation.

The solution is an easy one and not very expensive. Measure the diameter of the pipes involved and purchase foam pipe wrap to cover them up.

The tip of the day is when you measure the pipe you are measuring the outside diameter of the pipe and most pipe wrap is sold by the nominal size of the pipe which is the inside diameter.

The most common copper main is called 3/4, but it measures 7/8”, 1/2 copper measures 5/8. Galvanized pipe is thicker so 1/2″ measures 7/8” and 3/4” measures just over an inch.

It is usually sold in about 5’ sections for about $3 a ‘stick’. Purchase one more length than you estimate and use it to cut to size and wrap around valves and fittings that you will encounter.

The sections, ‘sticks’ are split to make it easy to wrap around the pipe. Some come with an adhesive to hold the foam tight to the pipe and some do not. The non-adhesive foam is held together as you install it with tape; I usually use electrical tape which I band around the foam about every foot or so to keep it mostly tight against the pipe.

Do not get to precise about the fit of your cuts because a little gap here and there usually does not cause a problem.

Some humid homes have a problem with toilet tanks getting too wet from condensation leaving puddles below the tank. The best solution is to get a foam insulation kit for a toilet tank which is difficult to install because it installs inside of the tank. Once done it does prevent the tank from getting ice cold during multiple uses in the spring and early summer. Once air conditioning dehumidifies the house and the incoming water from the city warms up as the summer goes on the problem will disappear.

The preformed foam insulation tubes for water pipes come in different diameters, on the inside and outside. For example, a 6’ foam piece for 1″ pipe is ¾” or 1″ thick – 1” insulates best, but ¾” is cheaper. The foam has a slit that opens the tube to snap over the pipe. The sleeve doesn’t close completely around the pipe due to joists and hangers in the way, so use tape sometimes.

Fiberglass rolls of insulation and tape are also used. The fiberglass strips are wrapped around the pipe with tape.

If you want to save money on hot water, first turn your water heater down to about 115° – 120°, next insulate your water heater with a water heater blanket kit, and then insulate the hot water pipes.