Insulating floors w/post and pier foundation

[CREATIVE1]

I am interested in using an expanding foam product to insulate the floor.  How high off the ground does the floor need to be to allow room to apply this material?

[skiwest]

Can't answer your question but couldn't you put sheathing on bottom of joists , 3/8 osb, and spray from the top?

If you were going to put sheathing under joists wouldn't it be easier to do with out the subfloor there.  Rather than crawling around underneath.

[John Raabe]

A mininum code crawlspace is 18" under the joists and 12" under beams. 24" everywhere is much easier and 30" is uptown.

If you are having a contractor sprayed foam such as Icynene, check with them and what space their equipment needs.

[Kodakjello]

Hey Creative1,

I'm getting Icynene sprayed on the underside of my pier and beam subfloor. I told the insulation contractor that there would be about 36" head room under the joists and he didn't seem phased at all. I would think that anything less than 30" would be a rather tight fit, especially in the summer heat .

Kodakjello

[MountainDon]

If you were going to put sheathing under joists wouldn't it be easier to do with out the subfloor there.  Rather than crawling around underneath.

It would be easier. I had similar thoughts. One problem that PEG pointed out to me was the danger if it rained before you got the thing dried in. And Murphy's Law would kick in for sure, for me at least. The forecast would be for 10 days clear, I'd have friends lined up and ready to help, materials all on hand. Then something would go wrong and I'd have only the floor done, water would fill the insulation cavity rather than leak through. I decided it wasn't worth the risk. YMMV.

[builderboy]

I insulated my 20 x 10 cabin floor from above before installing the subfloor. I then covered the whole floor with a large tarp wrapped down around the sides and fastened with wood strips. It wintered like that perfectly dry. Now I have my walls framed up right over the tarp and sheathed. Still dry. The roof rafters go on next. When I'm weather tight I'll cut the tarp out from the inside. Maybe not practical for a larger home but my solution to mtndon's concern.