Floorba insulation


Old 02-15-10, 10:40 AM
Thread Starter
Join Date: Sep 2006
Location: USA
Posts: 4
Floorba insulation

I have a 4' crawl space under my pier and beam 120yr old house in a coastal community. I am concerned about heat/air loss and moisture under the house. I have improved drainage on the property to prevent rain water from getting under the house and I have good ventillation. Now I want to install roll insulation between the 12" floor joinsts. The common wisdom seems to be to install kraft faced insulation with the vapor barrier against the floor. HOwever, I was wondering if I can leave the faced side of the insulation toward the ground, stapling the edges of the insulation to the ends of the floor joists. Could this do a better job of keeping the ground moisture away from the bat insulation and the house floor? OR....will it create a bad trap for moisture to hang out between my floor and the face of the insulation?
Please help....I need to install something soon.
THanks for all advice!
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Old 02-15-10, 11:54 AM
Join Date: Oct 2008
Location: New England
Posts: 9,990
The moisture issue has to be considered for summer and winter. We don't have your location, si I have to be generic. During heating season the house has a higher moisture content due to the warm air. If that air were to leak through to a cold air barrier, ie the kraft facing, it would cause condensation and potential problems. Thus the kraft is normally kept on the house side/warm side of the insulation.

HOWEVER, if you are in a warm, air conditioning climate, then location reverses and it is installed on the outside of the insulation, which happens to again be the warm side.

There is more to the issue than that and your desire to have a neat surface underneath is understandable. Although I have not used it, I do believe they make a breathable covering that can be stapled in place just like the kraft.

Having said all of that, in a heating climate, all/most of the warm air would be rising to leak out somewhere in the upper half of the house and cold dry air would be invading your insultaion and that does not cause condensation. So, despite the general guidelines, there is probably no risk.

As I said, more options may be available once we know your climate.

Old 02-15-10, 12:23 PM
Thread Starter
Join Date: Sep 2006
Location: USA
Posts: 4
thanks, Bud

That is very helpful info. Yes, I am on the Texas coast. So, generally we are very warm and very humid.

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