If the crawlspace (post and beam), is completely enclosed, is R-30 insulation still a good idea or is it overkill.
Thanks,
Frankie
Since it is enclosed and thus wind isn't getting under it, R30 is over kill. But if it is laying around go right ahead, but thinner would do just as much - vapor barrer to heated surface and some thing plywood to hold it up and keep critters from easily nesting in there.
Floors are normally insulated to the depth of the joists. It is important that the insulation be held up in contact with the subfloor and not leave a ventilated gap above the insulation. This is more critical than the actual R-value (which will vary with climate).
In a well insulated house all surfaces exposed to the same outside temperatures should be insulated to about the same level. Floors over sealed crawlspaces do not see the same climate the roof does, however.