Stone house insulation alternatives
Hi,
I am gut-remodeling a 1950s single story, stone slab-on-grade house in the Hudson Valley, NY climate zone 5A.
The house has problems with water/moisture, both from water infiltrating between the foundation and the walls where the soil has accumulated over time and from the flat roof with no eaves at the back which has been leaking. I plan to fix both of those, which I think control a lot of the water issues, but I’m unsure what the best plan to insulate the interior of the house is.
The current construction, outside to in, is:
10″ stone wall
asphalt tar paper/vapor barrier
fiberboard sheathing
2×4 framing
fiberglass batting
drywall
A lot of the fiberboard is rotting away from water exposure, but more than half the fiberboard seems to be in fine condition. Is it worth keeping this where it’s intact? I’m sure it’s not much of an air or vapor barrier.
I’ve considered removing all the fiberboard, which may be difficult to get out from behind the studs, and using a closed cell spray foam, but I’d like to avoid a spray foam product if possible. I like the air sealing I’d get from this, especially applied behind the studs, but wondering if there’s an alternative.
Are there any other products that could be used in combination with a rockwool batting or something? Would something like DRYLOK be a viable long term solution applied to the interior walls? I don’t want to crate additional condensation issues inside the wall if layered incorrectly.
Thanks!
Tyler
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Replies
Hi Tyler.
I'm not a fan of closed-cell spray foam either, but it can be a problem solver and I believe that this is a situation where it makes sense, like an old stone foundation. I think you'll need to pull out the sheathing so the CCSF can fill the gap between the stone and stud walls. With the appropriate R-value of CCSF, you could then fill the rest of the wall cavity with something much more environmentally-friendly like cellulose, if you'd like. In this case the CCSF gives you a WRB, air barrier, and vapor control. You should probably work with a local expert on a project like this.