REMOTE retrofit
I am in the climate zone 4 and I am working on the design phase of a REMOTE retrofit for a 1000sq ft home built in the 1940’s. The house is roughly 16×30′ and has two levels. The upper level is stick framed – 2×4 with board sheathing. The lower level is an 8″ CMU wall. The house is located on a hill and the basement is 8′ below grade at the front of the house and walks out to ground level at the rear (along the 18′ side of the house). In my REMOTE research it seems like ideally I would excavate all around the house to expose the footer and then proceed with the REMOTE system as described in the manual. However, budget limitations may prevent this. If I cannot excavate completely around the portion of the house that is below grade can I stop my REMOTE insulation on the exterior at the bottom of the rim joist and insulate all of the CMU walls and basement slab from the interior? Would it be better to continue my exterior insulation to 32″ below grade (the frost line in my area) and then insulate the basement from the interior as well? I haven’t seen any details yet where the insulation does not go to the footer and would like to make the most effective game plan as possible if we find excavation is not feasible. Also, based on the info above what rigid insulation would you recommend for these interior and exterior applications? Thanks for any feedback.
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Replies
Charles,
Yes, you can insulate the first floor on the interior, and the second floor on the exterior. If you go this route, it would be best if the rim joists (where the two types of insulation overlap) were insulated from both directions -- for example, with rigid foam on the exterior, and spray foam or rigid foam on the interior.
Most green builders prefer polyisocyanurate or EPS to XPS. Polyiso should not be used in contact with soil, although it can be used on the interior of below-grade walls (as long as you leave a 1/2-inch or 1-inch gap between the bottom of the polyiso and the concrete slab to prevent wicking).
Martin,
Thank you for the response. Interesting point about insulating the rim joist from both sides. I had actually planned on only choosing one side, most likely the exterior. It seemed like insulation on both sides would limit the drying capabilities of the rim joist.
Charles,
Once you have insulated the rim joist on the exterior with a layer of rigid foam, the rim joist will stay warm enough that there are no worries about moisture accumulation or condensation. That fact allows you to install vapor-permeable insulation on the interior -- for example, open-cell spray foam or even fiberglass batts -- so that the rim joist can dry to the interior.