Hello DIY Forum! [B]Question.[/B] [I][U]How can I tell if 2" x 10" floor joists under bath tub are rotten?[/U][/I] I have got a condo under contract for sale. I am the buyer. The condo was built in the year 1969. My unit is a second (top) level unit. The finish floor in the bathroom has a pressed [i.e. chipped] wood board finish floor. A repair man that is familiar with the building said the floor structure was 2" x 10" floor joists. The floor has been replaced sometime in the past because in the year 1969 chipped wood press board had not yet been invented. There is water damage at the corner where the wall meets the bath tub. The seller is going to remove the finish floor and the sub-floor. He then is going to let me have time to inspect the floor joists. I am going to have to lay down on the floor [belly first], shine a flash light between the floor joists, and then look underneath the bath tub. I was going to take a screw driver, reach up under the bath tub, and try and jab it into the floor joists. I don't think my arm is long enough to reach the floor joist all the way at the back of the tub. How can I be reasonably sure that the wood floor joists at the back of the bath tub are not rotten? Thanks.

I have searched but do not see a best case answer for my application. I have used pt lumber in contact with the concrete slab. I am now at the insulation stage. The floor was raised 18" above concrete, this created roughly 9" of open space between bottom of joist and concrete slab. And when its finished this area will have very little air flow. My question now is how to insulate install vapor barrier. Should I put poly directly on the floor and than plastic wrapped insulation between the floor joists? Should I try to get air movement by cutting in vent? Floor sheathing will be 3/4 osb. What is recommended?