I recently had some new stairs built that connect the first floor to the second floor, and I have a basement underneath the first floor. I'm curious about a couple of things: First, do I need insulation under the stairs? If so, what R-value should I aim for in Massachusetts? I was thinking about using Rockwool Safe'n'Sound, but I'm open to using standard Rockwool if necessary. Secondly, do I need to seal these stairs? What's the best method for sealing? Can I just use standard caulking, or is spray foam better for this job? I've been hesitant about using spray foam for personal reasons, but it seems this might be a suitable application for it—kind of like the method for sealing around rim joists. This is something I'm considering doing myself. Thanks in advance!
2 Answers
For sealing, it’s common to use caulking for gaps, but if you want a tight seal, spray foam is the way to go. Just keep in mind it expands a lot, so you might need to trim it back after applying. If you don't want to use spray foam, go with a good quality caulk and ensure you fill any gaps well. Doing this yourself is totally doable!
It sounds like your stairs are interior, right? Typically, insulation isn't necessary between floors if the stairs are inside. You could insulate if you're concerned about sound crossing between floors, but it's not required. Just make sure you're okay with how it might look since you’ll see the underside of the stairs if you look up from the basement.
Yes, they are the interior stairs, but underneath there are basement stairs. So, I guess insulation might help with noise transfer.
Thanks for the tips! I appreciate the info about the caulk versus spray foam. I'll consider the spray foam option carefully.