# Insulate basement ceiling?



## chandler48 (Jun 5, 2017)

Welcome to the forums. Your term "exterior insulated foundation" is a little illusive. Is it insulated on the outside? If so, how? Are the walls monolithic or cmu? Do you have walls built with foam against the wall, taped at the joints and insulation in the stud bays? I doubt you are having a heat loss in the upstairs floor.


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## stick\shift (Mar 23, 2015)

I don't understand the line about heat loss - if both spaces are conditioned, there is no reason to insulate between them. Where is this loss occurring?


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## Marq1 (May 31, 2021)

So your insulating the interior of a conditioned space, it's not going to hurt anything and you would not install any type of vapor barrier.

Your entire structure looses heat, insulation simply slows that process down. Putting insulation inside that condition space will not improve anything since the heat loss occurs elsewhere, the temps will just equalize. You may get a little sound benefit but it your looking to improve efficiency put that insulation on the walls/roof/floor where the heat loss exists.


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## Bud9051 (Nov 11, 2015)

Need a better description of the insulation you have. Also, suspect they did not air seal the perimeter rim joist to the foundation, a frequent source of infiltration.
As mentioned, sound reduction maybe, but you are not losing heat from the basement through the floor above. If anything it is going the other way.

Bud


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## House Designer (Oct 4, 2019)

If your first floor surface is cold, it would be more effective to improve (increase) your basement wall insulation, including rim joist. There is no need to insulate between conditioned spaces of basement and first floor level.


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