Really confused - sound & temp insulation

Old 02-19-03, 04:19 PM
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Really confused - sound & temp insulation

First let me say that I have read the other posts and the insulation documentation off of the homepage and the more I read the more I am confused.

I am trying to finish off a basement in the Mid-Atlantic. It was started by a couple of different owners and now I want to finish it off. It is in a townhouse and is about 20ft x 50ft. One wall is against the ground. Two other walls are common with other townhouses on each side. The last wall is exposed to the open air at grade and has a sliding glass door in it. We have a concrete slab floor and the walls are made of cinderblocks. We have no water/seepage problem (yet).

On the side adjacent to the dirt. It is currently framed with wood 1x3's directly touching the wall. First - should we waterproof this wall before we do anything (paint waterproofing material on it?)?We have no current water/seepage problem, but isn't it better to do this now when everything is exposed? Second, this framing is right against the block wall - I keep reading how the framing should be an inch away from the wall - do I have to remove this and re-frame farther away from the wall? Third - the frame is with 1x3's - is this too small to insulate? If I insulate, do I need a vapor barrier? I was thinking about kraft faced batts, will this work? If yes, on which side do I place the paper side (toward the wall or towards the inside of the basement.

On the two side walls - common with other townhomes, do I even need to insulate? We do not have a noise problem from the neighbors and since they are not exposed, I can't see how temp should be a problem. However, we will have teenagers in the basement and so I don't want to disturb the neighbors with our noise. I plan to frame in the walls - so I can add sheetrock/electric and have normal looking walls (looking a block walls looks like I am in a prison). I will use steel to frame in these walls. Do I need to keep this framing an inch away from the side walls if I do insulate? If I don't insulate? Do I need vapor barrier here? Which side for the paper side? Will insulation make any noticible difference in the sound - there is that block wall. I don't want to spend the money or time if it is not needed.

On the back wall which is exposed, since this wall gets very cold in the winter I already know I have to insulate. Do I have to frame away from the wall? Which side does the paper side go?

On the ceiling - I will place sheetrock, but the noise from above is terrible. What kind of insulation can I put up there to cut the sound? Does it need a vapor barrier?

There will eventually be a bathroom and there is already an interior room - I want to make sure I cut down on as much of the noise from one room to another. Is it worthwhile to place insulation in the interior walls? What kind? With a vapor barrier? The walls to the interior room are already up (metal frame with sheetrock), but are not finished. Is it worth the time to pull down the sheetrock (a bunch of screws) and put in insulation (for sound) or is it not worth it in terms of keeping things quiet?

Since I don't want to lose any height, is there any alternative to keeping the floor warm except putting in an insulated floor (rug with thick padding?).

So many questions....

Old 02-20-03, 11:00 AM
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The one inch gap does several things for you. One is that it acts as a buffer between the 2 different materials because they have different rates of absorption and expulsion towards moisture. Second, it has a fairly high R-value. This gap is also referred to as a dead air space. Air has very good thermal qualities. However, air that moves a lot because of temperature does not. Which is known as convective heat transfer. The lack of movement in this application gives the dead space high R-value characteristics, especially when applied to masonry walls. Not so when applied to wood framed walls.

Since you intend to heat the basement, you must use a vapor barrier towards the warm side when applying insulation. In the interior bathroom, you can apply insulation for sound purposes but do not apply a vapor barrier.

You do not have to rip out that section that is already framed out, just keep the insulation at least an inch away from the masonry. You may feel that this is not enough insulation, but remember, behind this wall is the ground and the temperature there will not be anywhere as severe as outside during the winter.

Water-proofing a dry cinder block wall as a precaution is something I do not agree with. It's not because I'm frugal. It's because a dry cinder block wall indicates that it is expelling the humidity created in the basement. The advantage you have over most basements is that only a small section of the basement walls have ground behind them. And the wall that is exposed to the outside and above grade will remove the vast majority of humidity in the basement. So I guess it wouldn't matter if you water-proofed that one wall, if it makes you feel happy or gives you peace of mind.

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