I have been following this forum for some time and have found it to be a wonderful, informative place. I just finished drying in my very small starter cabin. I have a vapor barrier installed over the floor joists and under the subfloor. I got a heavy rain one night before I got the roof up, and rookie mistake, had not covered the subfloor. I am sure the 3/4 ply got soaked. Is it now trapped or will it eventually evaporate through the ply? If it is trapped, should I try to go under the cabin and try to cut open some vents in the vapor barrier to get the water out? The down side for this is that with my foundation (pt lumber over crushed stone), I won't be able to get another vapor barrier on.
[highlight]Slice Away![/highlight] Get the water out, let it dry out and see if there is any real damage.
Don't worry about getting a second VB in under the plywood subfloor. The plywood is already a very good vapor retarder. You don't need anything else.
In fact make sure you don't put a vapor barrier material on the bottom of the joists after they are insulated. I have used heavy 6 mil black poly but you have to poke holes in it so it won't trap moisture.
If he slices the plastic he already has installed, the bottom face of the plywood will then be less protected against moisture present under the building. Wouldn't protecting the floor underlayment from moisture in the ground underneath the building or some method of minimizing the moisture under the building (ie. a layer of poly, drainage, ventilation) be an important consideration?
Tom
I laid 6mil plastic on the ground underneath my cabin. It has worked so far.
Kevin