Damp spots on sub floor????

Man I've really been hogging this forum.

When we pulled up the carpet, there were a few damp spots on the floor. They haven't dried out yet [img]/forums/images/icons/frown.gif[/img]

The largest (3-4 sq feet) is near the wall (maybe the wall is leaking?) One is under a bathroom upstairs, but the ceiling has no water stain/damage. A couple are in the middle of the floor with out any probable water sources. I've checked the basement underneath for pipes.

Any ideas what is causing this? Could it be old pet stains? (doesn't smell like urine). Methods for hunting down leaks? Should I try to dry them out?

""Could it be old pet stains? ""

Your question here made me wonder if the areas just look damp (stain), or are really damp (to the touch, or will soak up water into a newspaper laid on top)?

They feel damp to the touch, but my brain could be playing tricks on me. I'll try the newspaper test tonight.

Haz,

Take a piece of clear plastic and duck tape a 1 foot square down on the suspect spots. Tape them real well so they have a good seal on the edges. Leave them for 24 hours and see if there is any signs of condensation. This is a common test to see if concrete is to wet to put wood on. I don't see why it would not work on you sub floor.

The other thing that comes to mind are potted plants. Did you or was it a likely spot for plants to be set in the past? They often leave stain areas on a sub floor.

MarkV

Mark,

I'll give it a try tonight.

Put the newspaper down last night, forgot to check it this morning. [img]/forums/images/icons/frown.gif[/img]

Well,

Didn't get a chance to put the plastic down last night. Too busy making saw dust with the table saw.

The newspaper didn't absorb any water. Feeling the floor again, the "damp spots" feel cool to the touch, but so does the rest of the floor. Here's hoping that they are just stains!