Does insulation need to be installed in basement ceiling?

bwood74December 15, 2010

I'm going to stud out the exterior basement walls and install R13 fiberglass batts. Does the basement ceiling need the R19 batts too? The basement isn't really going to be climate controlled, but I was figuring on the exposed ductwork in the floor trusess might add something. I just didn't want to have to worry about the finished first floor above suffering. This house is being built in central Va.

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I'm going to respond to something you weren't looking for - fiberglass batts on basement walls are not ideal. Yes - it is done all the time but foam is better. I'm not up on all the arguments but the basics are that moisture comes out of the concrete and will cause mold/mildew in the fiberglass.

Far better to use rigid foamboard and I am pretty sure that you would be fine with R-8 - which would be 2 sheets thick. You can then put fiberglass on that if you want.

Code here would be insulate the floor. Anytime you have unconditioned space next to conditioned, you need to insulate. Even if the basement is always going to be mild temp.

I see what you are thinking - get some climate control from the ducting but that isn't allowed. And then maybe some more from the floor above.

Fiberglass is cheap. Insulating the floor is the right answer. My builder always insulates the basement floor even on a conditioned walkout basement. The reasons are sound (minimal) and if you don't want to heat the basement at different times then your 1st floor won't suffer.

    Bookmark   December 15, 2010 at 6:44AM
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The issue will be how you want to use the space.

The ducts are likely heating it now, from both leakage and radiation.

If you insulate them and isolate the space it will be even colder.

If you are wiling to use space heaters in the area it could still be worth insulating the ceiling if the space is only used a limited time each day.

If the area will be used daily for any length of time it would likely be better to get it inside the HVAC envelope.

The basement floor and exterior walls would then be insulated.

    Bookmark   December 15, 2010 at 9:07AM
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