Insulating floor joists?

I have a room that is over a crawl space. The room has hardwoord floors. Last year I had the permiter of the crawl, and the block walls stripped of the old wet pink insulation, and sprayed with the yellow foam. This definately helped with the temperature of the room, and the coldness of the floor. Would it be beneficial to also insulate (maybe with the pink stuff) the floor joists under the floor? I live in the midwest--10 to 30 degrees most of the winter.
thanks.
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Absolutely it would. You can use foam board, you can spray, you can use fiberglass.
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How does foam board attach? I assume that is the blue colored board? I would think the foam might be the most effective, but I can't install it myself.
Which is then more effective--the foam board or fiberglass?
I don't understand the comment about making the basement colder, this is above a closed off crawl space.
Edwin Pawlowski wrote:

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patrick wrote:

The foam board can be attached almost any way you can think of - nails, screws, adhesives. You can cut the board to make a wedge fit between the joists and use a can of expanding foam to seal the gaps.

Rigid insulation has roughly twice the R-value of fiberglass batt insulation.

The heat coming from the room above the crawlspace won't supply enough heat to heat the basement to any measurable degree. It's not a factor.
R
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Does the fact that he has HW floors make a difference in foam insulation, i.e. is it a fire code violation since there is no fire-resistant covering over the foam? Or does that apply just to walls?
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Buck Turgidson wrote:

The fire resistive barrier must be on the occupied side of the foam so it is acceptable to have rigid foam insulation in the crawl space.
R
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My understanding is that the building code specifies that a thermal barrier is required between the foam and the living space, and that 1/2" of gypsum board is a thermal barrier, but that it doesn't enumerate all possible thermal barriers. So some jurisdictions accept alternate thermal barriers, e.g. 5/8" of wood, in which case the subfloor and HW floor would presumably be sufficient.
Cheers, Wayne
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The person answering that did not read the message fully. It won't have an effect at all.
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Edwin Pawlowski wrote:

by code...I'm amazed that in the midwest this wasn't done. You'll save a BUNCH!
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House was built in '23......so no surprise to me.
Curmudgeon wrote:

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