What Are the Causes of Sweaty Pipes?

Cause

• On a base level, one singular cause leads to sweaty pipes: a conflict of temperature between cold water in the pipes and warm air, especially humid air. Just as it causes condensation on the outside of a cold glass on a warm day, warmth and humidity cause moisture buildup on the exterior of cold-water pipes. As cold water courses through pipes located in hot or humid areas of your home, condensation – or “sweat” – builds up on their exterior surfaces.

Effects

• Condensation collected on sweaty pipes can essentially cause these pipes to have the same effect on your household as leaky pipes, though typically on a smaller scale. Moisture from sweaty pipes can dampen walls, ceilings and cabinets, depending on the pipes' location. Depending on humidity levels, sweaty pipes can cause light dampness or sizable puddles, the latter of which occurs when enough “sweat” collects to actually drip off the pipe.

Remedies

• Running a dehumidifier in warm, humid areas with sweaty pipes, such as basements, may remedy the problem. Dehumidifiers dry the air and help lower the relative humidity and dew point. Wrapping pipes in foam insulation also helps cut back on condensation buildup. Using foam insulation on accessible pipes can reduce condensation on less-accessible connected pipes as well. Often, a combination of these remedies serves as the surest bet in the fight against pipe sweat.

Considerations

• Use a relative-humidity tester, available as a digital gauge at most hardware stores, to check the humidity levels near wet pipes. High humidity levels generally indicate that the pipes are sweating; if humidity is low, your pipes may be leaking. Sweaty pipes that go untreated may cause mold, mildew and foul odors -- or have an ill effect on the structural integrity of drywall and framing. Though hot-water pipes don't generally sweat, wrapping them in insulation can help retain heat and conserve energy.