Submitted by Wonderful_Promise_69 t3_123831q in DIY
Hello! I am renovating, and after removing the plaster and lathe in my kitchen I discovered that someone had poured concrete down the stud bays of all the exterior walls on the first floor. No idea why, (Misguided insulation? Racking support? DIY bulletproofing?) but it's there and I don't want to remove it in case the house has settled onto it and it is now a structural component. Also it's a few tons of rubble I'd rather not tangle with without cause.
My current plan is to create a false wall of 2x4's laid flat and screwed into the old studs to run electrical and some insulation. I'm hoping I can insulate with some foil faced EPS I have on hand to at least get some kind of R value. Anybody have any experience with this, or ever heard of it being done? I'm reluctant to lay the 2x4's longways as the kitchen is rather tight already.
pic of the concrete, the new studs are my addition https://imgur.com/a/OvLcHTt
Inshpincter_Gadget t1_jdtych4 wrote
Holy shit that's crazy bro.
Foil-faced insulation, I think, is completely vapor impermeable. If so, then you have to be ultra careful where you use it. Last thing you want to do is trap moisture inside your walls and end up with 50 tons of moldy stinky concrete wall filler.
In my climate zone vapor barriers are not really needed, so I avoid using them.
In cold zones you want the vapor barrier towards the warm in winter side of the wall, so that the steam from your hot cocoa does not condense into water droplets inside your wall.
If condesation is a concern then use the Rockwool product -- I forget the name.
Gosh, fucking concrete in the walls. Unbelievable.
Man, if you're brave enough to get rid of that shit... I wonder if closed-cell spray foam would replace some of that stiffness you are afraid of losing. (That would also be a vapor barrier, though).
If the studs are in good shape then I think the concrete isn't really doing much. There's that gap at the top of the walls. There's nothing sitting on top of the concrete, so I don't think it's really holding up anything.
I guess I'm just getting stuck on the idea of having such terrible wall insulation for the sake of keeping such a bunch of garbage inside the walls where the insulation should be.