Insulation Advice

[Welshman]

I have a 1300 sq.ft. unvented concrete block crawl space, with a concrete floor, in northeast Ohio. The crawl space is about 5 ft. high, with about 4 ft. below grade.
Which would be more efficient for keeping the house warm (or "comfortable") - insulating under the floor of the living space with R19 batt, or insulating the inside of the crawl space walls with 2in. foam board? If you can give me a brief explanation of why it would also be helpful.
Thanks.

[clarkie]

In my own home I have a crawl space, not as high as yours, which I insulated the walls throughout with sprayed in expanding foam. The floor joists are uninsulated. I have no problem with keeping the rooms above comfortable. If you help stop the inflitration through the walls of the crawlspace, hence the rooms above will not be cold or warm. If you insulated the floor joists without the crawlspace being vented, the possibility of mildew and mold could exist because of a damp, dark area. Is there a vapor barrier on the floor or under the concrete? My floor is dirt which I put heavy plastic over and I don't have any issues with moisture coming up thru the floor.
Good luck!

[DanW13]

I have a crawl space similar to yours, I took some rubber roofing and covered my dirt floor and then sealed the perimeter around the floor and insulated the floor with R-19 and will have before winter the outside walls sprayed with foam to seal and insulate them nd all should be good.

You sould probably do the same with your crawl space, once thats all done there should be no need to ventilate the area after you have it insulated and sealed from any outside air entering the space.

[heaterman]

If you insulate the floor, ventilate the crawl space. 2" foam glued to the block walls will work provided the crawl space is dry, remember to insulate the plate spaces and heat the crawl space for warm floors above.

[DanW13]

Someone's gonna get slapped on the hands !!!!

[Welshman]

Someone's gonna get slapped on the hands !!!!

I don't know what that means.

Thanks all for your input so far.
Heaterman: just to clarify - when you say insulate the floor - are you refering to the crawl space floor, or the living space floor (crawl space ceiling)? Thanks.

[beenthere]

A spammer made some post.
They were deleted, so you can't see them.

Dan saw the first one, and was posting in response to it.

[Welshman]

Thanks. Sometimes I confuse easily.

[heaterman]

Crawl space ceiling if not insulating crawl space walls.