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Community and Q&A

Insulating Unconditioned Basement Ceiling

ec83 | Posted in General Questions on

I have an old camp in southern Vermont built by hand in 1940.  There is a walkout basement, the walkout portion of which is finished and conditioned.  The remainder is unfinished and unconditioned, and housing the HVAC, well pump, hot water heater, etc. Two of the walls in that section are CMU masonry with a poured footing and the third is dry laid field stone. The floor is dirt with crushed stone.  As you can imagine, we get a ton of moisture intrusion, particularly along the fieldstone wall (although the CMU wall has a problem too – we run a dehumidifier constantly). Eventually we plan to replace the foundation entirely, but in the meantime we are just trying to do our best in terms of improving efficiency.  Currently, the joist bays of the existing ceiling in the unfinished basement area contain fiberglass bats.  The mice have had a field day up there, and between that and the age of the bats (35ish years), we are going to take it all out and clean things up.  

I know the preference from a performance standpoint would be to insulate the basement walls instead of the ceiling, but there is literally nothing we can do to stop the moisture issue without having to replace the foundation.  So, I’d like to insulate the joist bays again, but am weary of the rodent issue (we do a pretty good job excluding, but this house is so porous, it will continue to be an issue in the near-term).  What options would be best to address the need for insulation while being sensitive to the rodent issue?  I’m planning to take care of the rim joist pockets as well – that part is straight-forward. I’m just at a loss which ceiling approach would best meet my needs.  Maybe I can’t achieve this goal?

Thanks for your help!

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