Can you use Foam boards on basement walls to stop condensation?
I am finishing my basement and my basement exterior walls are fully framed about 2” away from the concrete. They have mineral wool in between the stud bays but not all dry walled yet. My issue is that since insulation was added on one of the walls (all others checked and fine) condensation is building up after I waited a month or so into winter and pulled the insulation out to check. This particular wall is not buried fully like the rest (due to slope of property) and it is exposed to the outside temps top to bottom from the outside so I know this is why this is occurring only here.
My question is now that it is after the fact how can I correct this condensation issue? If I install 1” or 2” foam insulation board sliding them in behind the studs and directly to the concrete wall will this stop the condensation or will it just build up on the inside of the foam board and still be a problem?
Hoping to just be able to apply foam to regulate the concrete temps and prevent inside warmer air from touching the concrete and condensating...but wanted to get opinions prior to spending $300.
Thanks
The air space is for sure causing the problem. The mineral wool batts don’t really impede air movement, but it would seem enough so that the moisture on the walls is not able to evaporate into the air. Installing EPS foam boards against the concrete would be wise, and though there would be minor amounts of air space given that a concrete foundation wall is never a perfect uniform surface, that should not be a problem. Any incidental moisture that did condense in a certain location would likely just be re-absorbed into the concrete. It doesn’t sound like an easy job to do – slipping rigid boards behind a stud wall – but it should solve the problem.
That should solve the immediate issue, but there are basement construction techniques that you may wish to employ so you have a durable and mold-free basement wall, this page will help –
How to fix and prevent mold in basement wall renovations
The biggest problem, as you would read about in that page, is the fact that standard basement construction techniques usually involve an interior vapor barrier, which will cause more harm than good. And a part of that problem is that Building inspectors often insist on a vapor barrier, despite the harm it can do. Will you be subject to inspections that you need to pass?
Thanks for the comment
I went ahead and installed the foam. It wasn’t easy but I’ve done worse. Had to cut each piece in 16” strips then slide in and apply glue to the wall and place the foam. Did this about 8 times and spray foamed around to prevent air infiltration. I feel good that this provide enough air block to prevent condensation.
My county has no inspections on anything you do within your own home building wise only if you do an addition on the home or plumbing so I am good there.
This has been a learning experience for sure. I have checked all other areas of concrete and they did not have any condensation on them (as most are buried either within 1’ of sill and the ones That go with the slope of the house are more buried than not). I have no plans on tearing out all the insulation on every exterior wall and applying foam as this “test” so to speak.
Thanks again for the link and input
That does sound like a time consuming fix Chad, but it should work. Best regards.