Subfloor Moisture: Hidden Threats & How to Protect Your Floors from Damage

[@joejesus9902]

But if moisture is deflected to the walls, would that cause moldy walls and baseboards? Thanks

[@CoronaHardwood]

Yes exactly. This is why the plastic is only a good option if you have very minimal moisture. Otherwise it will become problematic.

[@jeremyr1501]

We pulled up our old floor, and it had a moisture barrier and looked to be treated with a rolled on moisture prevention film. Underneath the barrier, there was a small amount of moisture in two areas (it looked like someone sprayed two sprays from a water bottle), and once exposed to air it dried up immediately. The floor boards themselves and the top of plastic moisture barrier were bone dry. Is this small amount of moisture from the slab normal? Or is this cause for concern and something that needs to be addressed prior to installing a new floor?

[@CoronaHardwood]

Yes this is completely normal. You will always have some level of moisture in your concrete. The roll on/trowel on products do not stop this transmission of moisture vapor, what it does is slow it down to a level that does not affect the flooring.