Mineral Wool Insulation directly under Carpet
pottsypotts
| Posted in General Questions on
Ground Floor existing concrete slab with 6mm poly on top. No water/damp issues. Low head height. Wanting to add insulation and carpet.
My idea:
Seamless layer of 1.5″ rockwool comforboard 80 or IS (higher compressive version), carpet right over the top.
Benefits: soft carpet underlayment and decent insulation add also saves head space from not needing the foam under carpet layer.
Im sure this is probably a bad idea but maybe its not!? thoughts?
My backup plan (original plan) is:
.75″ purlins 16OC with 0.75″ foam board in-between and 0.5″ plywood ontop then finished with foam underlayment and carpet.
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Replies
Comfort board is still pretty squishy, I can’t see it working in this application. You’d have the equivalent of carpet with a really, really thick pad underneath, and you’d likely sink in so far you’d damage things. I’d go with your backup plan, which should work fine.
Bill
pp,
Comfort board 80 compresses 25% at 7 psi. A woman's high heel exerts at least ten times that. The only way you could walk on that carpet without damaging it would be in snowshoes.
What about comfort board CIS? apparently it is much firmer to walk on. I laughed at the snow shoes idea, that would be a funny house rule to implement
PP,
Unfortunately Comfort board CIS still compresses by 25% at 10 PSI. Neither are a problem if you have some solid surface on top to spread point loads, but on their own you are going to see damage.
I don't want to stifle innovation or creativity, but a pretty good rule of thumb is that if you haven't seen something done in a building, there is probably good reason why.
Just to put some numbers to Malcolm's example, if we assume a 100 pound woman (which is probably smaller than average), and a high heel "heel" of about 1/2 inch square, you get 400 pounds per square inch effective force on the heel alone. This is worst case while walking and leading with the heel, which assumes that the heel will carry for the full weight for a short period of time. This becomes a very concentrated load that is going to be a big problem for ANY rigid insulation without some kind of subfloor above it.
Bill
Thanks Bill, I decided to use 6ml poly, 1x4 purlins tap con'd into the concrete at 16OC with 3/4" foamboard insulation inbetween and 5/8"s ply subfoor on the top. Will be doing carpet on top with the foam underlayment. Should be good!
I had a similar issue, used underlayment and half inch Eva interlocking foam with a carpet top. Kids have comfort underneath and it’s warmer, I have an exercise bike on it, no issues. Floor was also not completely level but doesn’t matter with foam squares. You can’t install a kitchen or a pool table but that isn’t the purpose. I could also remove at anytime in 2 seconds. Run a dehumidifier at 50, checked for signs of mold nothing there