Another basement insulation question

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  #1  
Old 02-17-04, 10:45 AM
PeterO
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Another basement insulation question

Hello,

I have perused many of the basement insulation quetions but haven't arrived at a conclusion for my situation. Hopefully, someone here might be able to help.

I have been slowly finishing a basement area that has cinderblock on 3 sides, 2x4 framing on the 4th side. I framed out the cinderblock areas with 2x4's (pt on the bottom in contact with the cement) with one exception - 2x2's on a portion of a wall in a bathroom that will have a tub against it. I am just about ready to insulate and don't know what to do.

There is not a water problem (we get some pretty good rains and I have not seen any water ever in the space) - the cinderblock walls have some sort of white sealant on them.

It seems that I should be using foam insulation - though I don't know what kind. I stopped by the local Home Depot and Lowe's to see what they had and the selections were pretty limited - just a few thicknesses instock. If I find the right tize (thickness), how is it 'held up'? Is it attached to the walls (between the 2x4's) with some sort of adhesive? Do I need to put anything else over it before drywall?

Any help is greatly appreciated.

Sincerely,
Peter
 
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  #2  
Old 02-19-04, 12:40 PM
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They have a mastic glue to put that polystyrene up on the walls with. But if you have 2X4 stud walls Id hang a V/B over the block wall and put R13 in the studs paper side to the room. A 4 mil poly over this then the drywall. ED
 
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Old 02-19-04, 02:20 PM
PeterO
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Apologies Ed, but what is a V/B?
 
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Old 02-19-04, 03:59 PM
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V /B stands for vapor barrier Like the 4 or 6 milpoly sheet you can buy. Also that paper on the insulation rolls goes to room side if you look there is like a blackseal on it this also is call a V/B
vapor barrier. ED
 
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Old 02-20-04, 06:11 AM
PeterO
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Thanks again for the help, Ed. The V/B acronym got me! Let me go one step further then...

The walls against the cinder block are, as I mentioned earlier, pt 2x4 on the floor, 2x4 studs, with two 2x4s on top - except for two sections where some duct work is located and in those areas, the 2x4 studs have been cut down by about 16in. I have not yet 'finished' attaching the walls - I have one of those .22caliber nail setters to anchor the walls to the flloor and plan on using some galvanized brackets every so often to attach the wall studs to the cinderblock. Of course, where I can, I am also attaching the top of the walls to the above floor joists.

On top of the cinder block, there is a piece of pt lumber (2x6?) onwhich the upper floor joists rest. Now as far as putting up the vapor barrier, if I understand you correctly, I finalize the walls, then place the 4/6mil plastic on the room side of the walls - pushing it back all the way to the cinderblock even though it will have an 'accordion' type look since it has to be on the room side of the 2x4 studs. Then I put the insulation batts inside the wall panels. Then I put the drywall on? Is this correct? Should I tack the V/B lightly to the studs to keep it in place? SHould I cut small holes in the V/B for wiring, etc.?
 
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Old 02-20-04, 07:17 AM
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The first V/B goes on or over the blocks first. From that sill plate that the joist rest on down to the floor. You nail the bottom P/T plate on the floor and the top plate to the joist. you only use one 2X4 on the top plate not 2 like for a home wall.Shim it if you have too to the joist and nail it to them. You DO NOT naill any wood or other to the block wall make no holes in it at all. Then the R13 in the studs paper to the room and then another 4 mil poly over this then drywall or panel ED
 
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Old 02-20-04, 11:37 AM
PeterO
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OK, I think I have it. Cinder block wall, 4/6mil poly (does it matter what thickness), 2x4 studs with insulation batts between, another 4/6mil poly, drywall.

FWIW though, I need to have the double 2x4 on the top to reach the floor joists above (and I just screws (5in) thruogh the double 2x4 into the floor joist?). At least that is how the walls worked out and I don't want to take them all apart - even though I will have to move them all to put the V/B behind them.

Since I will not be making any holes in the cinderblock, any suggestions about what to do with the two walls that don't go floor to ceiling becuse there is ductwork in the way? I realize this is getting a little off topic (insulation) but you've been so helpful that I will just keep bugging you!
 
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Old 02-20-04, 12:44 PM
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Dont know if Im right here or not on the 2 walls The bottom plate would go as one and the top plate cut out so it cleared the duct on each side.Now the studs 24"on center if they would hit the duct get cut off and a header or plate would go from the last full stud to the next full studand nailed on the short ones .Is this right ????

4/6 poly what ever I like clear best you can see the studs and all

ED
 
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Old 02-21-04, 06:45 AM
PeterO
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On the wall with the ducts, the ducts run right up against the wall for a 20 ft stretch. I can't really get behind them to put the wall all the way up to the floor joists above...
 
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Old 02-21-04, 01:10 PM
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Just how much room do you have from the duct to the wall? can you drop anything metal or wood down between wall and duct from the joist above and hold the wall. Or cut all the studs with the plates to go tight to the duct and put some screws up into the duct put some shims behind it to the wall so you can nail to the studs. Or will you box the duct in??. could make the wall 3/4" short. put 1"X4" nailed to the top of wall and stick out to where you would go up to the joist to box the duct in; this would hold it for you ED
 
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Old 02-22-04, 08:16 AM
PeterO
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I am going to box the duct in. It is all flexible duct. It is strapped to the floor joists tight up against the wall but one of the ducts (a batrhoom vent/light runs tight against the wall and exits the house so I can't really get behind it. I guess boxing it in might keep it tight enough against the wall?
 
  #12  
Old 03-01-04, 10:21 AM
PeterO
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After doing some thinking about this (and before installing the v/b that goes on top room side of the 2x4 studs), I was wondering why the v/b was needed on the room side of the studs if there is already a v/b between the cinderblock wall (that has waterproofing on it) and the studs...
 
  #13  
Old 03-01-04, 11:07 AM
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All I can say about it .Is we do it all the time, there can be some moisture from the cement so you put it there. Then in the winter from the home so we put it over the studs under the drywall or panel. You just dont want any moisture at all to get into the insulation .Even with the paper back kind paper to the room do it. Just had one on here Said had paper V/B on a home but now has water and brown stains running down the outside of the home. Some times the paper job is not to good and moisture goes out to the cold and froze in the insulation.ED
 
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