insulating basement walls

Old 12-30-01, 10:33 AM
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insulating basement walls

I have built walls in my basement. I put the walls against the poured wall. I have room for 3 1/2 inch insulation but I'm concerned about any moisture. Should I put in 2 inch insulation so I have a dead air space? I am putting up tongue and groove knotty pine on the walls. Do I need to have a vapor barrier? I have heard yes and no. Any opinions would be helpful.
Old 12-30-01, 06:04 PM
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Question Ditto for this question

I plan to also use standard 2x4 (16 on center) framing along poured concrete walls. I currently have no problems with moisture that can detect. I知 in a climate that stays relatively warm although we do see very cold conditions occasionally (Atlanta). Although I have a walk out basement, the entire area that I知 finishing is below grade. My plan is to use ス inch sheet rock on the studs and probably a drop ceiling system above. Also, forced air heat will be pumped in. It would be easier to have the heating/return vents near the ceiling. But, I知 willing to do whatever痴 best. Will this vent placement be a big problem?

Currently, the area is noticeably colder than the upper floors of course. I知 hoping that proper insulation will help fix that. Therefore, I知 wondering how I should insulate the walls and ceiling. Some articles suggest rigid insulation while others imply standard fiberglass insulation, etc. Am I taking a risk by filling in the space between the drywall and poured concrete walls with fiberglass insulation? Should I use a different type of insulation? Should I not insulate the walls at all and leave the air space (or leave a gap as DeWayne above suggests)? Do I need a 4-6mil vapor barrier behind the drywall? What about the ceiling? Although sound isolation would be nice, I知 really more concerned about keeping the area as warm as possible. I wouldn稚 think that the drop ceiling alone would be enough.

Thanks in advance for any advice,


Last edited by jazzyeric; 12-30-01 at 06:24 PM.
Old 12-31-01, 04:00 AM
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I'm also interested in the answer to this question as I will be framing in my basement soon. My house is newly built and I noticed when the contractor insulated all the the walls he put the insulation in first between the 2X4's and then put sheet plastic over the insulation stapled to the studs. Then he put the drywall over that. So I was assuming you would do it the same way in a basement. Seems to me as long as the poured foundation is not leaking you want the moisture barrier to be between the dry wall and the insulation as this is the most likely spot moisture would form because of the warm moist inside air meeting the cold air.
Old 12-31-01, 05:05 PM
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The contractor in the last post did it correct. There are really two ways to do it. One is put in batts of insulation that are completely sealed in a plastic wrap. These are becoming very popular. The other way is to put in un-faced insulation batts and then cover the entire wall with 6ml black plastic then drywall or osb board.
Old 12-31-01, 06:28 PM
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Finishing a basement

Go to for useful info. I have finished two basements. I applied two coats of masonry sealer, studs, insulation, and dry wall. The first project was drywall from floor to sealing. The second was oak wainscoating with drywall above and oak molding between the two. Both basements were dry, moisture free, and well ventilated. Although I had forced air heat into the basement area, I supplemented with electric baseboard heat. The basement recreational area was not frequently used unless we had guests, so I didn't worry about heating it. The only area that was frequently used was my office which I had studded out in a corner of the basement and dry walled. I had electric baseboad heat which I could crank up when I had to go to the basement and close the door. As a late night owl, that was where I spent most of my time. I could heat my personal area, crank up the computer, and plug in my coffee pot and pull out a bag of M&Ms without having to heat the whole basement.
Old 01-01-02, 02:54 PM
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Lightbulb Thanks & here's another opinion

Thanks for the responses to this question. After posting my question, I went on and did more digging on the subject. I thought you all might be interested in what Tim Carter posted about vapor barriers in basements. Take a look at

Basically, he says that vapor barriers in basements are a waste of time. Perhaps Jack's idea of the wrapped insultation (and no vapor barrier) is the best "middle of the road" approach.

Feel free to respond with comments. It seems that everyone has a different opinion about this one.

Old 01-03-02, 04:31 AM
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My foolproof method...

There are a lot of issues with vapor barriers and moisture coating, etc. that I have figured out a way to do it. Assuming you don't have any water leaking issues, this is what I do:

I glue one or two inches of rigid foam insulation to the concrete walls, floor to ceiling. Doing this is similar to the stress-skin panel method of roof construction that obviates the need for vapor barrier and ventilation. You don't need air space and you don't need vapor barrier this way. You then build your 2x4 or 2x3 wall up against the foam, attaching the bottom and top plates to the floor and ceiling and not to the wall (not necessary). You don't have thermal breaks where you have attached strapping or studs to the wall. You lose a couple of inches in room size but I challenge anyone to be able to tell the difference. You then have nice empty stud bays to run wires or ductwork in. remember to keep any cold air returns close to the floor.

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