Thread: Condensation?

I am only assuming that this issue involves condensation as opposed to a plumbing leak (read on).

We live in an A-frame cabin with a crawl space beneath. The underside of the floor joists are covered with OSB. The P-trap from the shower extends beneath/beyond the OSB and is insulated against freezing. At no time have I observed any leakage under this immediate area, nor seen discoloration in the OSB that would indicate any kind of plumbing leak.

It would be accurate to say that the OSB covering in the crawl space is not air tight, taking into consideration the cut-away area for the P-trap. That said, I have plugged any appreciable gaps with fiberglass insulation. Now for the interesting part.

As the colder weather arrived last year, we began to see moisture around the inside edge of the shower base, which is made of some kind of plastic. There is a very slight gap at the bottom of this shower base where you can feel colder air coming through. I should also mention that our primary source of heat is an efficient wood stove, which obviously has to draw it's air from somewhere. If it didn't draw incoming air, it wouldn't work properly.

Now, as the weather got colder, we began to notice more moisture along the edge of the shower base. As an experiment, we cut up a cotton sock and slid the edge of this fabric under the edge of the shower base. The result was that we usually wicked some moisture into the cotton fabric - some days more, some days less.

Today, the outside weather stats were: 20ºF, 63% humidity and a 12º dew point.

QUESTION: why was the cotton fabric totally dry after taking a shower? When I say "totally dry" I mean it wasn't soaked with water; it wasn't even as damp as it would be if you exposed it to live steam.