Rigid foam and air sealing on rim joist embedded into townhome party wall
Climate zone 4, NYC metro area, so fairly rainy.
In my townhouse there’s a pretty significant air leak where the rim joist/sublfloor/partywall intersect at right side (you can see how dirty the fiberglass batt is). On the plus side, the moisture content is ok at the moment and no signs of wood rot, which I thought might be an issue during cold weather, especially on a NE facing wall.
Normally I would insulate with rigid board and air seal no problem except there are two issues that give pause: 1) the rim joist is partially embedded into the party wall and 2) part of the rimjoist is up against concrete stairs on the other side.
I’ve attached some pictures to give a better idea. Inside and outside picture.
So the main question is – would this rim joist be okay to air seal and insulate – or should I just focus on air sealing the major air leakage points.
Insulating would be fairly easy since all the other joists run parallel to the front/back foundation wall so I would just need one long strip of rigid foam.
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