# basement insulation



## bobcatnj (Jan 4, 2007)

im framing out my basement and was wondering on the insulation. should i use the foam board or r13? also the foam board does it go on the 2x4's or behind the 2x4's. i talked to a couple people and got mixed anwers. im not in the carpentry construction field, i do landscaping, so im pretty new at this


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## theworx (Dec 20, 2005)

Have you checked out the difference in price between the 2 options??? Foam is not cheap!!! Personally, I'd go with the batt insulation and proper vapour barrier...


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## Cuz (May 5, 2006)

proper vapour barrier, could you get away with using tyvek paper on in a crawl space ? any pros or cons to this idea?


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## bobcatnj (Jan 4, 2007)

its not a crawl space and yes i put vapor barrier up. yea i checked out the price of the foam panels of 4x8 @ 13.00 each


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## AustinDB (Sep 11, 2006)

theworks may have been talking about sprayable foam insulation-which expensive! the downside w/ the 4x8 sheets you're speaking of is that once you cut them to fit between the joists-you've put in a lot of hours. Fill the joists w/ batt insulation for quicker results. In the off chance you were talking about tacking whole 4x8 sheets of foamboard up, I would recommend the batt insulation.


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## seekingadvice (Feb 23, 2007)

Another thing to think about, how much additional space are you looking to gain. It's not alot of space and is more expensive, but often we'll use 1 1/2" rigid foam between 2x4 on flat...If we build conventional walls, when possible we'll frame on the ground then staple house wrap before we stand the walls up, then bat insulation.
We also always use PT lumber for our bottom plate.


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## woodmagman (Feb 17, 2007)

Polystyrene "EPS" is great for insulating the interior of the foundation. Our codes require that is be covered by a minium of 1/2" drywall for fire and saftey reasons. A good thing about the product I use is that it does not emit HCFC during the manufacturing or after installation. HCFC's are linked to ozone depletion. 
A foam adheasive is used to bond it to the wall and then you can use a foam gun to seal the seams. Just one layer of 1 1/2" makes a huge difference. If you are installing on a cold day the difference is felt as you work. 
One person can install a 1000SF- 8 ft. height basement including joist spaces with one layer in about 10 hours.That is about 1100 SF of material.
There are systems for installing without using traditional framing. Our builing code requires the drywall to be mechnical fastened through the foam.


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## mikeybobo (Feb 18, 2007)

look into spray foam. It is expensive to have put in, but they do sell large cans, a little bigger than a propane tank for a barbeque with a dispenser gun. If you look into the spray foam extensively you will find that the first inch of the foam does 80% of the insulating. it is expensive to have someone come in and do a thicker coating of it, but look into doing an inch of it yourself, and then putting in batt insulation. I never liked the idea of having the craft face and the foam on the other side of the insulation due to a vapor lock, locking in moisture, so get unfaced batt insulation. supposivly the fome will breath enough so you can use the craftfaced but I never liked the idea. my neighbor installs spray foam, he's the one who told me about this method. He said its the best bang for your buck in insulating if you cant afford a full spray foam job.:thumbup:


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## Milhaus (Feb 11, 2007)

Check out building science.com. I was asking a similar question a couple weeks back, and did quite a bit of research on it. What I found was much the same as you, there are one hundred answers to this question!!

I live in a climate where temp fluctuates quite a bit. I found that you should not use a vapor barrier in a basement, as the walls need to breathe, or allow the vapor to move through them as much as possible. Ideally, an open cell spray foam(as opposed to a closed cell) is the best, but it is expensive. I opted to use extruded 1" rigid foam on the block foundation (make sure there is no vapor barrier on the foam), then I'll frame the interior basement wall, and insulate with fiberglass, followed by drywall on the interior. No vapor barrier. 

Mold is everywhere, it's how you handle it that counts.


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## Double-A (Jul 3, 2006)

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