Recently built a framed and truss shop building in Ohio. Will not be fully
heated full-time, but want to maintain just above freezing, so it will be
There are concrete footers below frost line, and 8"CMU frost wall to above
grade. The site slopes both directions, resulting in the uphill sides
having a frost wall that is approx. 3-1/2' above the floor slab on the
inside of the shop. The CMU is waterproofed and parged above grade.
The roof has had baffles and stuffed batt installed at the eaves prior to
the drywall going up, to allow blown-in in the ceiling, and the walls will
be done with dense pack cellulose ( blown in behind reinforced poly stapled
to the 2x6 studs then drywall).
What I'm trying to decided is what's the best approach for insulating the
frost wall on the inside. Can't fill the CMU's since there are too many
that were grouted for strength to prevent the hill from pushing the wall in.
And the building is already backfilled and graded so insulating the outside
is not an option.
There is a small step where the wall sole plate / treated sill plate sit on
the CMU. The options I've thought of so far are:
1. Build a "stud wall" out of treated 2x2, anchoring a sole to the slab,
putting 2x2 "studs" 48"O.C., and a 2x4 top plate ripped to fit against the
shop wall's sill plate. I'd cut 1-1/2" DOW stryrofoam to fit in between the
"studs", and top with fire-taped drywall. This would let there be a
mechanical attachment for the drywall.
2. Glue 1-1/2 or 2" DOW foam right to the CMU then adhere drywall to it,
taping the seams with fiberglass mesh tape. Might use the ripped 2x at the
top, nailed to the sole to reinforce the step that would result. Not sure if
adhesives are up to the task?
3. "stud wall" as in 1, but using poly vapor barrier over batts. This is
probably least attractive due to possible moisture infiltration into the
batt from block side.
Anyone have thoughts, observations, experience, or a suggestion for #4?
Thanks in advance!