Ask Me Help Desk - Inulating basement walls

Hi everyone,
I found many useful informations here while working on my projects.

I'm finishing my basement.. the Concrete wall is almost 9' high all the way around. The wall is insulated 1/2 way by the builder with a plastic wrap all the way around. I have framed the walls by 2"x4" wood with fireblocks midway... my question is: when insulating the walls, do I insulate the entire wall, and cover it with the vapor barrier, OR just the bottom 1/2, the area not covered by the builder? Planning on using unfaced insulation with a vapor barrier. Thank you

I would not use unfaced insulation against the exterior vaporer at all. Use the polystyrene foam boards not the white styrofaom boards. I'm a builder and the 'half way" is not correct. The correct way is to liquid nail the pink 1 1/2 or 2" ridge Owens and corning foam Bord onto block walls Then spray foam any gaps to the bottom floor joist and around joist to seal air out. Use tongue and grove foam board and caulk the tongue and groove Tuck tape all seams no plastic vaporbarries are needed on foam or walls now.

If you want you can run your electoral conduit surface apply that onto foundation wall and then use the foam board over that cut out outlets and furring strips over foam and the drywall.

If just 5% of moisture gets into the unfaced insul it looses 95% of its insul qualities not to mention possible mold.
The unfaced is used above ground and it HAS to be in a non damp room and it needs to breath on the cold side and air flow and the barrier is on the heat side. Polystyrene is the only good way to go in a damp basement and can take the general dampness on both sides and keep its "R" value and inhibits the start of mold.

Signed 21 Boat

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Quote:

Originally Posted by 21boat

I would not use unfaced insulation against the exterior vaporer at all. Use the blue polystyrene foam boards. I'm a builder and the 'half way" is not correct. The correct way is a continues vapor barrier on the foundation wall taped and sealed and the the foam board and to studs.
If just 5% of moisture gets into the unfaced insul it looses 95% of its insul qualities not to mention possible mold.
The unfaced is used above ground and it HAS to be in a non damp room and it needs to breath on the cold side and air flow and the barrier is on the heat side. Polystyrene is the only good way to go in a damp basement and can take the general dampness on both sides and keep its "R" value and inhibits the start of mold.

Signed 21 Boat

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I'm sorry, I neglected to mention that I live in chicago area, and I thought the vapor barrier can be used on the winter-warm side, which would be my basement walls, right?. I originally wanted to remove the builder supplied insualtion, frame the walls, then insulate the entire walls, but now its too late. The problem with the foam boards, is the walls are at least 2 inches and some areas even 4 inches away from the foundation walls. They won't stay in place.
so, you're suggesting to not use unfaced insulation.. how about if I just use faced insulation say, R-13 on the 1/2 wall that I framed only. BUT how can I seal both sections of the wall (the builder with vapor barrier, and mine) with 2x4 block in between

They will stay in place if you sue liquid nail caulk. See the problem here no matter what is on the summer side or what ever ALL vapor barriers go on the HEATED side of a wall. That's the interior of your room which that application is fine but you have a double whammy here the foundation is another barrier and a barrier to barrier is a big No NO If any vapor was installed it would be on the studs under drywall stud side. Again It has now trapped the moisture in behind wall to basement wall. Sorry I know it's a bummer to hear this but no matter what faced or unforced doesn't change the moisture trap between the studs and foundation walls

Signed 21 Boat
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Quote:

Originally Posted by 21boat

I would not use unfaced insulation against the exterior vaporer at all. Use the polystyrene foam boards not the white styrofaom boards. I'm a builder and the 'half way" is not correct. The correct way is to liquid nail the pink 1 1/2 or 2" ridge Owens and corning foam Bord onto block walls Then spray foam any gaps to the bottom floor joist and around joist to seal air out. Use tongue and grove foam board and caulk the tounge and groove Tuck tape all seams no plastic vaporbarries are needed on foam or walls now.

If you want you can run your electoral conduit surface apply that onto foundation wall and then use the foam board over that cut out outlets and furring strips over foam and the drywall.

If just 5% of moisture gets into the unfaced insul it looses 95% of its insul qualities not to mention possible mold.
The unfaced is used above ground and it HAS to be in a non damp room and it needs to breath on the cold side and air flow and the barrier is on the heat side. Polystyrene is the only good way to go in a damp basement and can take the general dampness on both sides and keep its "R" value and inhibits the start of mold.

Signed 21 Boat

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So the best way, is to completely remove the insualtion installed by the builder, use the foam boards onto the walls as you described without any vapor barrier...

Yes all insul goes. Foam board only. I hate to tell you that but It has to done right. Its like a good foundation footer. This way you will be mold free and warm and use less heat to heat the room. It's a little pricey to use the foam board and if it has to be done in budget stages at least the results will be perfect no worries later. I'm Glad you come to terms so to speak and it pleases me you will now have a GOOD room when you are done.

Signed 21 Boat

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Quote:

Originally Posted by 21boat

Yes all insul goes. foam board only. I hate to tell you that but It has to done right. Its like a good foundation footer. This way you will be mold free and warm and use less heat to heat the room. Its a little pricey to use the foam board and if it has to be done in budget stages at least the end results will be perfect no worries later. I'm Glad you come to terms so to speak and it pleases me you will now have a GOOD room when you are done.

Signed 21 Boat

If I helped To Answer Your Question Please Rate My Answer

Thank you very much.. you're answers were very helpful, and informative.