Insulation in overhead floor joist in basement
#1
04-14-16, 07:44 PM
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Insulation in overhead floor joist in basement
The builder installed kraft faced fiberglass insulation in the floors. So when you look up in the basement the fiberglass is showing and the kraft face is on the other side (warm side under 1st floor subfloor). I am finishing the basement and am wondering do I leave it this way or pull it down and pull off the kraft face.
#2
04-14-16, 08:48 PM
If you are going to finish the basement and condition that space as living space, it doesn't matter. Only purpose it will be serving will be a touch of noise reduction. The vapor barrier issue comes up when you are insulating between conditioned and unconditioned spaces.
Be sure to air seal the rim all the way around the top of the foundation.
Bud
Be sure to air seal the rim all the way around the top of the foundation.
Bud
#3
04-15-16, 03:37 PM
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Thanks for the response. I am confused when you say the issues occur when a vapor barrier is used between conditioned spaces. The upstairs is conditioned...heat in the winter and central AC in the summer. The basement does not have AC, and will have electric heat that is used when the basement is in use. Should there be no vapor barrier then between the two floors? Should I remove the kraft paper that is under the first floor and just leave the fiberglass?
#4
04-15-16, 04:10 PM
The Kraft is not a vapor barrier, it is a vapor diffusion retarder. It will slow the movement of moisture but it will still allow drying. Perfectly fine right where it is.
When you say you are finishing the basement, to me that says it is or will become conditioned space. It certainly won't be what mother nature is offering us on the outside.
Your priorities should be to air seal the perimeter of that basement ceiling and insulate that area if they didn't. If they didn't air seal, then it must be done. I use an infrared camera and the house to foundation plus all of the seams allows a ton of cold air to flow in.
Once the basement is properly sealed and insulated (the walls) then you will want to share the heat and ac from the house above. Basements will inherently have moisture issues as moisture vapor will go right through the concrete and even wick up from below the slab and footings. It isn't always a lot, but it requires managing on the inside.
Bud
When you say you are finishing the basement, to me that says it is or will become conditioned space. It certainly won't be what mother nature is offering us on the outside.
Your priorities should be to air seal the perimeter of that basement ceiling and insulate that area if they didn't. If they didn't air seal, then it must be done. I use an infrared camera and the house to foundation plus all of the seams allows a ton of cold air to flow in.
Once the basement is properly sealed and insulated (the walls) then you will want to share the heat and ac from the house above. Basements will inherently have moisture issues as moisture vapor will go right through the concrete and even wick up from below the slab and footings. It isn't always a lot, but it requires managing on the inside.
Bud
