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Got a large issue that I can’t seem to understand. This is at my uncles house.
House built in 1922 time frame. 12″-18″ rough block foundation walls. Very uneven, rough, unlevel, etc. Plan was/is to finish the basement. Never have ever seen a drop of moisture from the walls, even though there on some cracks. And I mean, in 25 plus year, there has never been a drop in the basement.
I started by filling in any cracks with crack filler and sealing other gaps. Then I got some 1/2″ insulation board that I glued to the wall using proper glue. Followed that by taping all joints. After that was done, you could feel coldness on the joints but the insulation was fine. It was actually amazing how much warmer the basement felt with just R3. Next I framed up 2×4 walls. This is where is goes badly.
All the framing is done. Was just about to get going on electric and drywall. Get a call that there is water on the floor. Upon inspection, I am seeing wetness along the bottom of the walls where the insulation meets the floor. The outside portion of the walls is showing some signs of sweating also, even thought temps have been around 20-30F.
I don’t know what to do, I don’t know where this moisture is coming from all of sudden. Plan was to then put r13 bats in the wall but now this have put a stop to everything. Don’t want to continue to only end up having huge mold problems.
Any suggestions? Should I of painted dry-loc on the walls first? I guess I didn’t think of it as we have never had moisture in the basement.
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My guess would be the foam insulation board you glued to the wall. It is trapping moisture in that was previously was able to evaporate.
Chad
A Working Pro since 1993
Member since 12/07/2013Do you think spraying 2″ to 3″ of closed cell spray foam over the entire wall, including joist spaces above help? It’s just weird as there never has been any moisture on the walls.
Jonathan, My guess is that you have a fairly high humidity level in the home and a fair bit of moisture migrating through the wall. With the insulation on the wall, the passage of moisture is stopped at the back side of the insulation where it condenses and runs down to the floor. prior to the insulation, the moisture would just diffuse into the air in the basement.
I would start with a good water weal on the inside of the block wall to keep the moisture from migrating through the wall. The second thing I would do is use closed cell spray foam on the wall. This will seal to the wall and not allow a place for moisture to condense between the wall and the foam. In the Minneapolis area you should have an R – 10 on the basement walls as a minimum. you would have had that with the r – 3 foam and the R – 13 batts, that system puts the vapor barrier (the foam) on the cold side of the wall (against the block) and not the warm side where it should be in our climate. Additionally, batt insulation is not recommended below grade. It is allowed by the code, but it is not a good choice.
unfortunately this option requires a lot of rework but it is the best way to accomplish your goal. Additionally, when you have the foam insulation sprayed, you could also insulate and air seal the rim joist area which would result in significant energy savings also.
I would remove the existing foam and spray a waterproofing agent on the wall then closed cell spray foam. The key will be to make sure there is not an air gap between the foam and the wall which you can not get with rigid foam. even a gap of 1/8″ or less can allow moisture to condense and run down the face of the insulation board.
My guess would be the foam insulation board you glued to the wall. It is trapping moisture in that was previously was able to evaporate.
Bingo, amazing what happens when you make a change. Follow Kurt’s advice above.
Automotive Pro
Fayetteville, NCGreat advice from Kirt.
Did you use a sill plate gasket? In your picture I’m not seeing one.
“If you don’t pass on the knowledge you have to others, it Dies with you”
— Glenn BottingDidn’t check the thread again last night before I hit the sack. Kurts advice is spot on and I agree that is the route you need to take to remedy the problem.
Chad
A Working Pro since 1993
Member since 12/07/2013@themagicone sounds like Kurt gave you some sound advice,
Another thing, I assume the age of your home, they didn’t do anything on the outside of the block for waterproof prior to backfill,
Eventually if you have any work to be done outside around the foundation, it’s probably a good opportunity to have some sort of waterproof membrane applied,Good luck, looking forward to hearing how you make out with this.
That solves the inside issues.
What would cause the 1′ section of foundation that is above ground outdoors to seem to be condensing also?
I thought by using 1/2″ to start would be flexible enough to get mostly tight to the block. $400 in foam…
What would cause the 1′ section of foundation that is above ground outdoors to seem to be condensing also?
My guess would be, that the condensation that would have normally go into the home is now finding its way through the block to the outside.
“If you don’t pass on the knowledge you have to others, it Dies with you”
— Glenn BottingCan’t add much more other than insulation is all about dew points and where that occurs in the wall assembly. The R-3 was not anywhere near enough to put the dew point where it needed to be. In that assembly you want the dew point to occur in the foam where it wont really condensate and do any harm. We use 2″ ridgid foam on the insides of our new basements in our climate zone. Depending where you are located determines your needs. Ultimately closed cell spray foam not open cell, is the best but most expensive type of insualtion for below grade. DO NOT put fiberglass over that R3…it will be a huge sponge!!!
Andrew
A Working Pro since 1995!
Member since March 26, 2014.
Well right now I am thinking just doing a 2 to 3″ spray of closed cell foam over everything. Including the rimjoist. This will basically seal the foam board to the concrete. That will seal the inside. Not sure what to do if moisture is coming in from outside. But if it stay the same temp as outside/block behind the foam there won’t be any way for it to condensate. Ripping the 1/2″ as starting over would be a lot of work being that glue I used is really strong.
Well right now I am thinking just doing a 2 to 3″ spray of closed cell foam over everything. Including the rimjoist. This will basically seal the foam board to the concrete. That will seal the inside. Not sure what to do if moisture is coming in from outside. But if it stay the same temp as outside/block behind the foam there won’t be any way for it to condensate. Ripping the 1/2″ as starting over would be a lot of work being that glue I used is really strong.
Don’t think that’s going to work out too well for you.
Building science is a complicated subject, and if not understood properly, can lead to destruction of buildings.
Old buildings were not designed to be airtight, and a tremendous amount of moisture moved freely through the building and dissipated. If you seal a section improperly, you can cause a great deal of damage.
Besides, spray foam over the boards is unlikely to stop your moisture migration issue.
Delta
Goin' Down In Flames........
Crisis averted I think. Finally got back over and from the look of it, it is just some water from really wet lumber. I pulled the bottom plates out and did not see any sign of water on wall/floor behind them. Really just some water under the plates. Then moved the stack of wood and saw water under that.
I pulled a section of foam off and the wall was bone dry. Plus we are only sealing like half of the walls so there is plenty of space left for the basement to breath.
Did the lumber come from a yard that stores it outside? Seeing you are in MN
Maybe frozen and while in your basement had time to thaw?“If you don’t pass on the knowledge you have to others, it Dies with you”
— Glenn BottingMy guess would be the foam insulation board you glued to the wall. It is trapping moisture in that was previously was able to evaporate.
my thought as well, only other thought would be bottom plate fasteners allowing water to come through the floor, but i would lean more towards above
I cleaned up the few spot I saw water at. In the photo you can see water in front of the plates but behind and next to it is bone dry. It was fairly humid outside and inside today but didn’t any more water on the floor.
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Do you have a foam gasket under the plates on the floor? You’re supposed to. Never fasten wood directly to concrete.
I also second Kurt’s previous advice.
A couple of free online publications you may want to download and read.
Pre-WWII homes…..
Basement insulation…
https://www03.cmhc-schl.gc.ca/catalog/productDetail.cfm?cat=178&itm=195&lang=en&fr=1482555094919
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