Hi, my name is Tim. I was speaking with a Billy Boerner in email as he is a local St Louis area inspector. He informed me that it would be best for me to post here. As I am aware that topic regarding vapor barrier and moisture in basements have been beaten to death, I still want to discuss it given my skepticism with things. I also am not sure if this was the right thread to post in, but after viewing the other threads, I felt this might suit it best.
I live in Cottage Hills, IL which is near St Louis. As you are probably aware our climate consists of temperatures as low as 0 degrees in the winter and as hot as 115 degrees in the summer at times. Our winter months can vary in temperature drastically here, as the other day it was 70 degrees and last night our low was 20 degrees. O happy days. Either way I would like to discuss how I should go about framing up my basement. I have read and read and read different ways to go about it and have an idea of my own that I think might best fit my application. I will present it, and see how you guys feel on it. I will also give you an idea of the type of house I live in.
My application is a below grade basement in front with a walkout basement in back. I have a sump pump that was installed before I bought the house, when and how I do not know, but from doing some jackhammer work already in the basement it appears they have a slotted pipe with clean rock on top of it. It appears that it was done correctly. It also appears to work very well. I have a cinder block foundation, I doubt the outside was every waterproofed on the below grade side. The house was built in the 60s. I live in Cottage Hills, IL. My backyard tapers down to a creek that is probably 20 feet below my house or more. Just wanted to give you an idea of what were working with.
I am wondering if I should even use a vapor barrier in my construction. It appears from this website that people frown drastically on them. I have seen a ton of pictures that would explain why. I have also experienced first hand about the rigid foam board insulation installed against the cinder blocks with slats in between, as this is what was installed already. I also had an area in the basement where just studs were installed right over the cinderblocks with no gap between the block and board, but it was never finished just left roughed in. The cinder block walls are dry locked as well.
The area where the rigid foam board was installed was growing mold at the very bottom of it between the foam and the blocks. It was a slat against block, foam between with laminated paneling installed over it. Mind you my basement has a sump pump system, the area where the mold was in this application likes to stay damp, and had it stayed dry, probably wouldnt have grown mold. I do not know why the bottom one and a half bricks hold moisture, but they do. It is just in one corner of my house.
As far as the studs that were installed right on the cinder block wall, they have grown some surface mold. At one point in that corner of the house the dirt was up over the siding for some reason and the guy that installed my panel box didnt seal around the pipe where enters the house through the sill board, so water would flow through that hole, into my box, down the walls, into the studs. That could be why their is more mold there also then should be.
Either way I do not have standing water in my basement at all, moreso dampness along some of the cinder blocks near the floor. The drylock in those areas have bubbled up as well due to hydro static pressure. Hopefully everyone is still with me and I am explaining myself well.
I have since tore out the rigid foam board install, which was probably 20 plus years old to begin with, but do have the studs still up in that one corner. Nice way to experiment with things in my opinion anyways, you live you learn. Here is my idea.
I want to reframe part of my basement very soon. I am not sure what to do with the dampness yet at the bottom, but I do intend on drylocking the rest of the basement. It has held up well over the years since I have never finished it on the higher portions of the walls, but like I said, not at the bottom. Not sure why, maybe the surface wasn’t clean enough or something it was applied. I also intend on framing a 2x4 wall with a 3 inch gap behind the wall. I am thinking I should not use a vapor barrier at all. I was told to use a plastic or foil wrapped insulation in the wall if no vapor barrier is used, but I think I would just go with regular unfaced fiberglass between the studs instead so it can BREATHE more. I also considered not putting the insulation all the way to the floor to help aide in breathing. As far as the framework is concerned I have a couple ideas. Their was one thread that showed a guy using composite decking as the bottom plate, then treated 2x4 as a second bottom plate, then the non treated studs, with non treated top plate. I thought that was a very sound idea. Then my mind started to wander a bit. I began to think well, composite decking is very expensive. Why not just space the composite material that is being applied to the floor, since I have two bottom plates this would be fine. By spacing the composite decking, I would allow a gap under the wall so that the wall would never sit directly on the floor and be able to breathe that much more, therefore never being expose to water and never wicking any water up into the walls. Another thing that came to mind was not bringing the drywall all the way to the ground, but stopping it above the treated bottom plate giving myself a 2.5 inch gap between the drywall and the basement floor, preventing that much more wicking into the drywall if the treated board ever got wet. I also went as far as to think wrapping that treated board in a sill sealer, foam product to prevent any wicking if the water level ever went above the bottom composite decking spacer. ALSO since the composite decking is wider then a 2x4, i would fur out the composite board to be plum with the thickness of the drywall, so that when I put trim up around the perimeter it would be flush and cover the area that is not drywalled.
Hope this all makes sense. Thoughts? I will take some pictures of the mold/damp area that was under the rigid foam board insulation and the picture of the mold on the studs. Foam board area like I said was over 20 years old and the stud area is probably 6 years old.