I'm currently renovating my basement and have all my foundation walls lined with polyiso boards. I've used 20ga metal framing for the interior walls, separated from the slab with sill seal. I'm about to build a partition wall to separate the finished basement area from an unheated garage. I initially planned to use 6" metal stud framing and insulate it with fiberglass batts, but I just realized thermal bridging could be an issue since that's connected to an unheated space. If I add a 1/2" layer of polyiso on the garage side of the partition before putting up the plywood, will that help with insulation enough, or should I switch to wood framing to improve R-value? Is the difference with metal studs really that significant?
1 Answer
Honestly, if you're putting in the work, consider insulating the slab too. It may cost a bit upfront, around $1.75 per square foot, but it will help cut down on thermal bridging massively. If you don't need heavy stuff on the floor, you might not need plywood on top. Just make sure to build your wall on top of the insulation to eliminate any bridging. As for your partition, yes, adding foamboard between the metal framing and the unheated garage is definitely worth it! It will be a cost-benefit thing, of course—will it save you in energy bills over time? That's something to think about.