Insulating floor of an old barn
I have an 1804 bank barn and plan to use the lower level as a shop. Since dirt falls through the floorboards above anytime I walk upstairs, I need to think about insulating as a first step.
The easy thing would be to spray open-cell foam on the ceiling (bottom of 1.5″ floorboards); but, I’m concerned that the foam won’t maintain an air seal when people and machinery move around upstairs.
Rigid foam boards would be extremely tedious, since every beam is different and nothing is square. Creating a ceiling is just as tough for the same reason. I don’t know if it makes sense to stretch plastic and blow in cellulose from above. No other ideas come to mind.
Does someone have a good idea on how to do this?
Thanks.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Open cell foam is fairly flexible, but the wood needs to be pretty clean to get a reliable bond.
Putting up an OSB or plywood ceiling on the under side of the joists with ring-shank nails (or screws), then blowing the joist bays full of cellulose would probably be a better bet. If the spacing is all over the place, install some 2x4 furring 16" on center first, and fasten the OSB or plywood to the furring.You can seal the seams of the sheet goods with tapes, and the wood ceiling can handle the weight of cellulose and flexing of the floor. There would be some blow-by of cellulose through the seams of the plank flooring above when installing it, but it would stay in place otherwise.
Thanks for the good advice about open cell foam.
I was trying to avoid installing a ceiling because each beam is a different thickness, a hand- finished tree trunk with a notched end to make the floor level; but, it seems I must.
Maybe this calls for a drop ceiling, where I can adjust the lengths of wires, instead of shimming furring strips. Does anyone know how many inches of cellulose a 2'x4' ceiling tile can comfortably handle and the appropriate spacing for the wire hangars?
Thanks again.
Michael,
Suspended ceilings with 2'x4' acoustical tiles aren't airight. You can't use that type of ceiling to enclose cellulose.
Another option is to install a new plywood subfloor on the barn floor above your shop. The barn floor won't look old-timey, but it will be easier to sweep.
-- Martin Holladay
If you use 2x4 furring, OSB/plywood ceiling, and blown cellulose you don't necessarily have to shim it at every beam, or at all, unless you insist on a perfectly flat ceiling.
Thanks for the ideas. I think my idea is to use 20' 2"x 12", ripped into six pieces and strung under the beams at 16" to carry 3/8" plywood. I can't attach plywood directly to beams because the height changes up to 4" and the spacing is very irregular.
With furring that skinny you may need to shim & fasten at every intersection with an old beam.