GIMME SHELTER-Moisture mystery: When water haunts the floor

Brian Gillispie, Gillispie Enterprises LLC

Q: In the hot weather when the humidity is high, my wood floors "sweat" in certain places. How do I stop this from happening?

A: Although it's sometimes hard to remember what hot weather is like during these cold winter days, humidity is a real problem in the hot summer months. All wood has some moisture in it, as does the subfloor, the basement, and the air itself.

Controlling the moisture level in your house is key to preserving your wood floors. We see floors damaged by moisture all the time– usually the floors are badly "cupped" because of too much moisture in the subfloor. We always check the subfloor with a moisture meter before installing a floor. To prevent things like cupping and warping, the moisture level in the subfloor should be below 14 percent– ideally, around 9 or 10 percent.

In most cases, however, spot sweating is caused by moisture in the room itself. Installing a dehumidifier on the heating system or buying a standing dehumidifier for the room should fix the problem. In older houses, sweating is sometime caused by condensation on copper pipes running under the floor, but, again, a dehumidifier should take care of the problem.

If the dehumidifier doesn't stop the moisture from rising up on your floor, it would have to be internal; either the subfloor or the basement has too much moisture, or the pipes are sweaty or leaking. Again, a good dehumidifier should be the answer to all your moisture problems– except for leaking, of course. Also, you might want to give the area a smell test. Sometimes these moisture spots turn out to be places where pets like to relieve themselves.

If you continue to have strange moisture problems, you might want to check the tax records on the house to see if it was built over an Indian burial ground. You could have a poltergeist!

Brian Gillispie