How do you fix moisture problems in basement?
I am redoing a basement wall that has a lot of moisture and has rotted the studs I see you mentioned to do drywall, studs with mineral wood then 2" of rigid insulation attached to block foundation would it be ok if I put Delta MS against the block foundation then apply the rigind insulation Thanks for your help.
Putting a membrane like Delta MS against a foundation wall before studs is a great idea. Keep in mind though, that moisture may drain down the interior or the wall, so ideally you would have a trench at the bottom, and even bring the membrane under the sill plate of the stud wall if you can to prevent moisture damage to the framing members. Or, check out something like this vented sill plate to reduce moisture damage on basement walls.
That way you keep your stud wall dry and don’t have to go through this again in the future. And a question – what is your climate zone? Insulating old block foundations from the inside can be a bit risky in really cold climates, as they are accustomed to staying warm with a lack of insulation. Suddenly being exposed to the freeze / thaw cycle of bitterly cold winters can cause the mortar in the joints to crack, just something to be aware of. Also check the current state of the wall to see if there are any structural concerns, and if so maybe consult a pro to see what a safe level of insulation would be that you can install. 2 inches of insulation is most likely fine, It's just something I wanted to put on your radar in case you are in Alaska and have an already cracked block foundation is all :)
Thanks Mike Im in Toronto zone 6 I see what you mean by the Delta membrane not having a place to drain to. Im going with the other option on your site using 3" closed cell sprayed right onto the block wall then using PT wood for framing with FoamSealR 3-1/2 in. x 50 ft. Multi-Use Ridged Sill Plate Gasket do you think I should also put Roxul on the 2x4s or is that overkill? Also if the closed cell gets moist would it just evaporate to the inside and would that create any mildew on drywall really appreciate your help on this its very hard to find good information out there. Thanks jr
Hey John,
My only concern would be the condition of the block wall and possible cracking. Is it in good shape? If so, and you go for it I would suggest the following - PT isn't really necessary, I would frame the stud wall an inch away from the concrete blocks and sit it up on small 1 inch high foam blocks (one cheap sheet of EPS from a local building supply store would be all you likely need) so the spray foam can get under and behind. That way your wood is prefectly protected. As for the spray foam, my other suggestion would be to choose a spray foam with more climate friendly blowing agents- read more here. There are a few companies that have switched to much less harmful blowing agents, they are also said to be a lot less toxic to humans. Below you can see what I mean by foam blocks, it just keeps the wood off the concrete. The wall isn't structural so the weight isnt't a problem. As for putting batts in the cavities, once you're already going with the spray foam you might want to just save myself the headache and labour of doing a how round of batt insulation and get them to thicken that to the desired R value you want. They charge by linear foot usually so adding an extra 2 inches of spray foam while they are already at it may actually be the cheapest solution, but price it out both ways I guess.