Vapor barrier

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  #1  
Old 12-15-04, 07:03 AM
packy40
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Vapor barrier

I have the 6 mil plastic ready to go against my basement walls. I have a couple of questions.

Where do I attach it? I'm assuming that I staple it to the sil plate or the studs, sitting atop my concrete walls. Is this correct?

How far down does it go? Do I simply let it rest and gather on the floor? Do I tuck it under the bottom plate of my framed walls?

I'm sure I'll have more questions as I progress.

Thanks,

Packy
 
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Old 12-15-04, 07:26 AM
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hi
first of all you dont put plastic film over the cement wall.
if you going to finish the wall with drywall, first you need to create a stud wall. the bottom plate mjust be preassure treated lumber and the other studs regular lumber. anchor your wall to the top joist and secure the bottom with crip con nails or tap con screw. then insert insulation between the stud that are 16 " cc
and then place vapour barrier over it anil staple to the stud. Also make sure you insulate betten the joist around the sill plate to cut air and used vapoour barried there too.
then install drywall over your insulation
hope this helps

cheers

pg
 
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Old 12-15-04, 07:40 AM
packy40
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Thanks for the info. But, I was under the impression that it was useful to put a vapor barrier both between the stud walls and concrete and then between the insulation and drywall. Thus, creating "dead air" between the barriers? Is this not the case?
 
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Old 12-15-04, 08:19 AM
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Wink

Have been putting the 6 mil poly V/B on the walls first. Staple to the sill plate and hang down to the floors. If it fits set the P/T bottom plate on it. A R 13 in the studs and then another 4 mil poly over them then the drywall.Now for over 30 years in basement's and earth contact homes.
have been back in many and had no problem at all. Dont forget to put a R 19 up there on the sill plate in each joist space also.

ED
 
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Old 12-16-04, 06:53 AM
Shadowman
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I've seen three ways recommended and never a definative answer.
1. Hang poly from sill plate down
2. Hang poly from slightly above grade level down
3. Don't hang poly against the cement.

For what it's worth, the Canadian guide on insulating a basement chooses option #2 and I've seen cdn home reno shows follow that as well. Maybe it's a cold winter climate thing. Also, you won't see anyone using faced insulation here as it's not rated as good a vapour barrier as using unfaced and poly.
 
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Old 12-16-04, 07:22 AM
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Shadowman
That is why we have always used paper back and staple in the studs Then a 4 mil poly over the whole ceiling in the upstairs let it hang down some on the walls . Then a4 mil poly over the insulation in the walls.

ED
 
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Old 12-16-04, 08:23 AM
Shadowman
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Yeah I just mention it because I've noticed so many people here talking about using the faced stuff and I find it interesting that it's fairly hard to find around here. Don't really see the point in even using it if you are still putting poly up. I guess it could help in overhead work to keep it in place, although I still rarely see it even then, they seem to just rely on friction fit. That and if it's the common type to sell around you, then there's not really a choice, heh.
 
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Old 12-16-04, 06:46 PM
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Vapor barriers

Plastic vapor barriers are NOT designed to be placed directly over concrete basement walls UNLESS the plastic vapor barrier terminates BELOW the concrete floor or into a peripheral drain.

Otherwise any condensation that forms bwteeen the masonry basement wall and the plastic sheeting will simply pool on top of the floor and cause rot to wood framing members, mold and mildew formation and damage to flooring.

But whether or not you should use plastic is dictated by local codes, and while in Canada plastic vapor barriers are required and should be used, in most parts of the US they should NOT be used unless the plastic terminates over the footer under the concrete floor.

In fact, it is a code violation in most parts if the US to use plastic vapor barriers in a basement where the barrier does NOT terminate below the concret basement floor slab.

You will get your proper answer by consulting your local code enforecment office.
 
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Old 12-24-04, 04:41 AM
pixal
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How about XPS foam

I heard XPS foam is semi permiable. Is it ok to use XPS foam without the peripheral drain?
 
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Old 12-24-04, 07:06 AM
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lets see have been just hanging the 4 or 6 mil poly on the basement walls and earth contact homes . Then the insulation. paper back or not then another 4 mi over that for over 30 years now and have had no trouble with any of them.

ED
 
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Old 12-24-04, 08:59 AM
darren_1974
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I use poly on the concrete too, but only to grade height, then R13 in the stud wall, then 6 mill poly. The poly directly against the concrete wall is runvertically so it has overlapping seams every 7 feet or so. These seams ar not sealed. This is code up here in Canada. The poly against the foundation only serves to keep the fiberglass from getting wet if there ever is any water seepage through the wall. We build our stud walls 1 inch from the foundation wall.
 
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Old 12-25-04, 06:42 AM
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In Canada, That is Correct

In Canada, it is Code and is correct to use 6 mil poly plastic sheeting in walls, ceilings and in basements. The reason is that the plastic is there to keep all water vapor out of walls because of the excessively cold climates.

In the States, except for some of the most northerly, it is not proper to use 6 mil plastic sheeting in any wall or ceiling, and is only allowable for basement walls when the plastic sheeting is placed directly against the masonry wall, is taped at all seams, and the sheeting terminates below the plastic.

Ed Idumec apparantly has been doing it wrong for 30 years and has no intent on changing his ways despite the fact his practice remains incorrect...
 
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