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Old 03-17-2014, 10:18 PM   #1
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Another basement flooring insulation question

Hi all, first post.
I am in the process of finishing my basement. I have searched the forums for info on cork as a thermal break and can' t find any info. Does anyone have any experience using it in this manner. I have seen it promoted as R-60 but have a hard time believing this and I couldn't find good info on the internet. I used 2" XPS on the walls. My ceiling height is low at 7'6" so I would like to avoid the XPS/plywood option if possible. Any info would help. I live in the northeast, Staten Island, NY. I think I am in zone 4, not sure though.

I tried to post a link but forum wouldn't let me.


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Old 03-18-2014, 12:08 AM   #2
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Something's way off in the R value you posted.
Even 1/2 thick it would only be about R 1.63.
What's the plan for the finished floor?


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Old 03-18-2014, 06:46 AM   #3
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Downward energy loss through the slab is vastly overstated. Is the basement full below grade or walk out?
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Old 03-18-2014, 07:08 AM   #4
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I don't believe the slab is that important to insulate. Some people only insulate the top couple of feet of the wall and ignore anything that is under grade by more than a foot or two.

Also, doesn't cork absorb and hold water? Not sure it would be good for an area that can flood.
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Old 03-18-2014, 09:11 AM   #5
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Joe- I agree that the R value is way off. I tried to post a link of the claim but I don't have enough posts. If you google cork as thermal break and click images you'll find it. As far as finished floor I haven't decided yet but I wanted to get some type of break.

WOW-It's not so much energy loss I am concerned with(well it is) but more to make the floor less cold, for. If that makes sense. Majority of walls are below grade, three are above grade ranging from less than a foot to about 2 feet. One wall is completely below.

Mike- I Sprayed foamed the rim joists and sill plates, sealed any air gaps and leaks I could find. Then put the 2" XPS on entire wall surface, figured it was best way to go. As for the cork I'm not sure. I've read that is a good thermal break and it is impervious to water yet I have also read that it absorbs water, so I agree with you that it shouldn't be used in an area that will eventually have type of flood. That's why I turned to the forum for some insight.

I just don't want to go through all this work to have a floor that transmits the cold, I get that it is a basement floor and it won't be as warm as the main upstairs but I likes to get it as comfortable as possible is the goal. I have radiant flooring upstairs and played with the idea of putting in but then I loose some ceiling height and of course the cost of installing.

Thanks again for input.
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Old 03-18-2014, 10:51 PM   #6
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R-5 XPS will give you warm toes. Just Delta FL (or similar) will stop the moisture rising. Payback;

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