Help with detail for Basement Sill/Rim Joist/Building Shell intersection
NW Arkansas, Zone 4a, Mixed Humid
So this would have been fairly straightforward, but the concrete plans changed and now I have to adjust. 4″ of foam and veneer got added to the outside of the concrete. I moved the walls out 1″ so there wouldn’t be so much underhang. Because of a time issue, the basement walls were poured short, with the understanding I’d find a a way to make up for it with wood (the top of the floor can’t be any lower).
Picture 1 is a rough idea of where things “should” be. In Picture 2 I moved the wall back inline, primarily because we are in tornado/storm country, and it seemed the simplest way to maintain the uplift load continuity from the mudsill. And I simply stacked another 2.5 inches of lumber to reach the bottom of the joists.
I am not very satisfied with Pic 2, though it may not get much better under the circumstances. So I’d love some feedback.
I also have some notes and questions:
– It will be a conditioned but unfinished basement. I expect the concrete to find a fairly dry steady state, being so far off grade and open to the conditioned interior. Therefore I’m not terribly concerned about capillary wicking into the mudsill board, but I have a strong urge to put some of the waterproofing liquid membrane I’m using on the outside of the basement wall on top of it as a capillary break. What I am concerned about is the condensation of summer air (primarily outside air) on the cooler concrete. It seems it could always be damp with moist air leaking under the sill plate. So the foam is great, but I’ve also seen details of a foam/metal flashing/foam sandwich there, which seems reasonable. Or just two layers of foam?
– Not in the plans are various lines of caulk around the board edges, I also forgot to add spray foam on the interior of the rim joist.
– The anchor bolt location is the actual location of the most inside one I measured. Most should be much closer to the midpoint of a 2×6 sill plate.
Thanks.
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