I have fiber cement siding, over tyvek, over 1" r-board, over 1/2" OSB, over 2x6 framing. Because of the way our storm shelter was built, the porch cap was poured monolithic with the walls below at the time the basement was poured. This resulted in having the exterior walls of the main floor sitting on top of the concrete porch. Floor joists hang from a ledger board that is bolted to j-bolts embedded in the porch cap. I used peel n' stick waterproofing between any wood and the concrete (sills, joist ledger boards, wall plates, etc).
I had asked the framer to leave a 1/2" gap between the OSB and r-board and the concrete just to keep moisture from wicking up to them.
We are making changes to the porch framing, so we exposed one wall of the porch and I took off the tyvek. This is a 6ft wall that I had not noticed where the gap between the foamboard and concrete starts at 1/2" at the corner but the last 2 ft towards the outside of the porch the foam is right on the concrete. The last foot and a half does get rained if the wind is right. It looks like the foam is wet here, and this was maybe a week since it rained. There is a framed column right next to the wall built with 2x4 and covered with OSB/Tyvek that was not sided. I took the tyvek off and this OSB was also touching the concrete, and it's soaking wet. The framing is only treated wood on this column, no waterproofing used on it. Doesn't look rotten yet, but I can't be good for it. So I had to check the rest of the walls.
There is a 2" gap per trim instructions between the bottom trim board and the concrete inside the porch that is covered with 6" of pvc coated aluminum . The Tyvek overlaps the top of the pvc aluminum behind the trim. I took the trimboard off and the aluminum and the rest of the walls seem to be fine. The 1/2" gap is there. The interior of the main floor is not finished, so I checked the OSB from the inside at the wet spot, and it felt dry to my touch. I plan on cutting a section of the foamboard off to check the condition of the OSB from the exterior. The exterior is only 2 yrs old.
I am wondering what I can do to waterproof this gap and more importantly, how to waterproof the trouble spot. I'm pretty sure the problem is water wicking up from the wet concrete, more so than rain getting behind the wall. And also what to do with the column. We were planning on using stone for covering the bottom 2 ft or so of the column.
I was thinking of filling the 1/2" gap with vulkem where the walls seem to remain dry even when it rains. But the spot towards the front of the porch where it gets wet, I'd like to do something more than that if needed.
The column I was thinking of replacing the OSB with cement board for the bottom 2 ft where stone veneer will be applied. But the framing is only treated wood with tapcons into the concrete porch. Should I take the column down, put some peel n' stick under the bottom plates and re-install it? Or will it be ok if I just caulk the joint of the wood to concrete before installing cement board? The bottom of the plate will still be in contact with the concrete. I do need to confirm and see if the framer put anything under this column like sill sealer or something since I don't remember using any waterproofing here.
Any help or guidance is appreciated.
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