Quote:
Originally Posted by Superflyer
I have an unfinished basement that I'm wanting to insulate the ceiling in because my main floor floor is always cold in the winter. I have joists that are 16 inches deep but the thickest insulation I can find is 6 inches. Should I just push it up to the top and leave a gap on the bottom?
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Is the basement insulated and heated at all? If so, I wouldn't bother with any insulation, I'd just keep the basement warm enough that the floor isn't too cold. Insulating the floor can work, but normally not that well unless you really get the details right and to proper air sealing.
If you do want thicker insulation, you can usually buy R28 or R40 fiberglass. Or alternatively you can always just stack 2 layers of insulation.
Quote:
Originally Posted by EverfresH15
I would do the opposite, leave a gap between the floor and the insulation.
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That's not always code compliant (though it may be these days). Sometimes it can work better, as it keeps warm air under the subfloor and raises the floor temperature slightly. But it sort of relies on excellent air sealing and insulation installation to prevent any cold air bypassing the insulation and getting into the cavity. To use that method, I think they also recommend rigid foam across the bottom of the joists with taped seams to prevent cold air infiltration.