Insulation choices for zone 6 basement
RockfordHarley
| Posted in General Questions on
My brother has a house in zone 6b, with a unheated basement, that is usually pretty damp.
He began installing fiberglass insulation between the floor joists in the basement. He put the kraft faced side down (facing the basement), since he thought that would prevent any condensation from developing directly under the floor. I told him to wait until i asked here.
But, this is wrong, right? If hes set on using fiberglass insulation, should he remove the kraft facing, or turn it around so the kraft facing faces the heat, or leave it as is?
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Replies
The kraft side is a vapor retarder and should be closest to the warm side of the house--in this case, pointing up.
He should really address his damp basement. It's not only an annoyance but a health and safety risk, as mold and wood-rot microbes can thrive in such an environment.
If he has AC, then keep the kraft paper on the bottom. With no AC, I don't think it makes much difference which side the kraft paper faces. It is a vapor retarder, but so is the subfloor. And yes, something should be done about the moisture.
It's likely not what he wants to hear, but it's better to address the moisture issues in the basement, vapor seal & insulated the slab & walls than to try and separate the basement outside the conditioned envelope.
You can find several articles here at GBA about why bringing crawl spaces inside the condition envelope is a good idea. The same principles apply with an unheated basement.
Thank you all for the replies and insight, hes gonna pull it out and address the damp issues first.