Has anyone ever heard of fiberglass insulation batts that are 29" wide? I'm trying to insulate the floor of my 1860 house and I'm stumped by the joists, which are set 30" OC. I can't seem to find anything wider than 24", or anything (like rigid foam board) which could be cut to that width reasonably efficiently.
There are lot of these houses around -- I figure there must a solution out there. But so far no luck. Ideas?
John
on 12/14/2007 2:21 PM jgold723 said the following:
Blown in insulation. Available at the BORG, including a blower rental.
48" x 96" sheets would yield 3 @ 29" x 48" leaving 9x48 waste which is less than 10%.
closed cell foam blown in over R6 per inch. seals air infiltration too
way better than fiberglass
Don't you mean 28" ? They must be rough cut which would mean they are actually a full 2" wide.
I've never heard of wider batts than 24". What I would do is take a
24" roll of fiberglass insulation and cross cut it into 29" pieces or whatever and install them crosswise in the joist space. Alternatively you can cut a little strip, to add to your 24" batts, though this can be a PITA if you are relying on friction to hold the batts in place. Lots of labor, but then that's an old house for you.for under the floor???
swhat do you hope to accomplish insulating a floor?
sand if you insist, i agree the sprayed in place closed cell foam will do the trick.
Well i insulated my dining room floor thats above a unheated garage. it helped a lot.
John,
There's no reason the batt has to run parallel to the joists. Cut narrower batts into lengths that would fit between your joists.
For instance, You could buy 24" wide insulation, and cut it into 29" lengths. With eight foot batts, that would give you about three sections per batt. However, with four foot batts, you would have a lot of waste.
I've also seen 4x8 sheets of rigid foam insulation at Home Depot. You could cut three 29"x48" sections out of each sheet.
Another option would be to attach some kind of barrier to the underside of your joists (1/4 inch hardware mesh, for instance), then blow in loose fill insulation. Just don't use a vapor barrier like plastic sheeting that would trap moisture.
Another option, add a joist in-between your existing joists. They wouldn't need to be the same depth as your existing joists (they wouldn't bear any weight), just deep enough to span the distance without sagging. This should let you install regular 15" batts fairly easy. However, if you did make them the same depth as your current joists, you would end up with sturdier floors as well.
Anthony
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