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Another basement insulation question!!


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07-07-05, 09:41 AM   #1  
billy_5555
Another basement insulation question!!

Hi. I'm insulating my basement walls. the only question i have at this point is is it ok to put rigid foam insulation directly onto the brick walls? I had fiberglass insulation there for a couple of weeks and found moisture on them so i think i should use the foam insulation.
thanks.

 
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07-07-05, 10:30 AM   #2  
billy_5555
basement wall insulation

Hi,
i'm putting new insulation on my basement walls - is it ok to put rigid foam insulation directly onto the concrete walls? the fiberglass insulation had some moisture on it after just a few weeks of being on the wall.
thanks.

 
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07-07-05, 10:35 AM   #3  
Thats why we hang a 6 mil poly on the cement walls. Then put the insulation in the studs paper to the room With a 4 mil poly over that.

ED

 
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07-21-05, 05:24 AM   #4  
In addition, batt insulation is always better for this application since it fills the gaps better and is easier to work with.

Mositure on the walls has nothing to do with the type of insulation you use...it will return without a proper vapour barrier.

 
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07-22-05, 05:46 PM   #5  
You can glue rigid foam insulation directly to the concrete wall. You don't have to use a moisture barrier with foam panels. I suggest surfing to the manufacturer's site and reading their instructions. There are also many online articles that discuss how this can be done.

 
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07-22-05, 07:14 PM   #6  
Another basement insulation question!!

Last I heard rigid extruded polystyrene with properly taped joints was a completely acceptable vapor barrier. It also does not absorb the moisture that lowers the insulating value of fiberglas. (305 to 50% insulation reduction with 1/2% to 1% moisture are the numbers I consistantly hear).

Don't try it with the cheap expanded polystyrene (bead board) since is not impermeable.

This lets you eliminate the wood studs if you choose this route.

Dick

 
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07-23-05, 07:47 AM   #7  
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I was originally going to go that route but when I priced both methods it was the same price to stud up walls.

Putting up walls is much better. More solid and sturdy for hanging shelves, plus lots more room for electrical boxes.

 
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07-25-05, 05:04 AM   #8  
Posted By: Concretemasonry This lets you eliminate the wood studs if you choose this route.Dick
Be careful if you are suggesting to use metal studs. The following are the downfalls...

1. In cold weather, the metal studs will show through the drywall.
2. You must add wood blocking to add strength in any spot where you will hang a door frame or cabinets.
3. You need to add grommets to pass the electrical wires through so that the insulation on the wires is not accidentally cut.
4. Ideally you should add wood blocking at the base so that you can nail the baseboards. Without this blocking, you cannot nail baseboards.
5. It is strongly recommended to use a special drill which spins at 4,000rpms to attach the screws.
6. Metal studs have sharp edges...there is a good chance you will cut yourself during installation.

 
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07-26-05, 10:59 AM   #9  
Check out this site. These guys have done a lot of research and travel all over the country explaining the right way (as he has determined) to insulate houses.

http://www.buildingscience.com/

The current line of thinking is to place the rigid foam insulation directly against the foundation and tape and seal it. Think of it like putting a cold drink can in a huggy. Then if you need more insulation (depending on your location) you can frame a wall in front of it and place batt insulation in the wall. Oh and remember to insulate the rim joist as well, that can cause major problems if you insulate the rest of the basement and leave that area open.

 
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07-26-05, 02:34 PM   #10  
Another basement insulation question!!

Good solution!!

If you plan to finish the wall, you could use staggered layers of extruded polystyrene instead of on thicker layer. - Better vapor barrier and you can try running any electrical in the layer near the wall and have a continuous layer on the surface (Just a thought).

Some of the newer low expansion foams are compatible and very helpful with a system like this.

Importantt - Make sure your concrete or block wall is as dry as possible. Use a water repellant material on the surface. Drylok (well advertised) or something like Thoroseal (time tested and cheaper).

Dick

 
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