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Vapour Barrier Between Garage And Living Area??

 
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Old 12-02-2008, 01:50 PM   #1
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Vapour Barrier Between Garage And Living Area??


Hello,

I need a little direction.

I am insulating and VBring between an unheated attached garage and living area ( both on the side and above)

Now, we have insulated and vb the garage as well as gas proofed it.

My question is this.

Where the garage shares a wall with the living area should we vb the garage side or the living area side?

Normally we vb the heated side, but here we have to worry about the garage gases so it's better to put vb on the garage side. But this sie will be cold and it would condense I think with moisture coming through from the heated ( living side)

Thanks
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Old 12-02-2008, 03:33 PM   #2
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Re: Vapour Barrier Between Garage And Living Area??


big builder, suprises me alittle you do not know this, but I am gonna try to help you. your not going to heat the garage to the same temperature as the house, so YES, install your "vb"

how do you "gas" proof....?

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Old 12-02-2008, 06:46 PM   #3
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Re: Vapour Barrier Between Garage And Living Area??


hmmmm, that gives me an idea, when I finally get around to remodeling the bathroom maybe I'll gas proof it against my 11 year old son. Yeeesh he's rotten.
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Old 12-02-2008, 07:48 PM   #4
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Re: Vapour Barrier Between Garage And Living Area??


Quote:
Originally Posted by bighammer View Post
big builder, suprises me alittle you do not know this, but I am gonna try to help you. your not going to heat the garage to the same temperature as the house, so YES, install your "vb"

how do you "gas" proof....?
Not because hes a builder means he knows what hes doing, here in Toronto we have builders all over the place anyone pickup a hammer is a builder, it means hes a sponsor aka "builder", i came across a guy that told me hes a builder, and when i asked him what excavator he dug the hole with, what nailer he got, what gauge of electrical, he new nutting, little did i know his daddy owned a jewellery store and give him money to flip houses, and that makes him a builder, seems like pretty boys with ties feel, if they got that title it ill make em more ruff and tuff .........................big hammer this is not towards you, just had to vent that
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Old 12-02-2008, 11:00 PM   #5
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Re: Vapour Barrier Between Garage And Living Area??


Are you Double Rocking as well???
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Old 12-02-2008, 11:59 PM   #6
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Re: Vapour Barrier Between Garage And Living Area??


Vass is das...."gas proofing"
of vich you speak?

Vapor barrier on the house/warm side.
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Old 12-10-2008, 04:20 PM   #7
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Re: Vapour Barrier Between Garage And Living Area??


Yes, double sheet rock too.

Why is it when you are VB the ceiling of a garage with living area above it you vb the cold side ( ceiling of garage) not the hot side ( which would be the under the subfloor above)? MY question was specifically which side of the wall...the house side or the garage side. Doing the house side is better for keeping the humidity from condensing but doing the garge ( cold ) side is much better for keeping the gas from entering the living area.

Gas proofing is simply making sure carbon monoxide or diesel fumes cannot make it thru the walls or ceiling inot the living area.

These days we take extra cautions after the advent or remote car starters. Do you know that there is one brand of car starter that if trigger a certain way will start your car every 30 minutes for 15 minutes?
That is scary if you and your kids are sleeping under the same roof.

FYI-Rotarex. By any definition of the word professional builder.... I qualify. I have Owned a successful custom constrution company for over 20 years and I am on the site everyday and in the office every night.
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Old 12-10-2008, 05:10 PM   #8
 
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Re: Vapour Barrier Between Garage And Living Area??


If your insulator is not putting the retarder (there is no such thing as a vapor BARRIER on any insulation product no matter what the manufacturer says) to the warm side in the garage ceilings, he is not doing you any favors.

He may say that there is no way to get a "seal" by putting the retarder to the top but that is not true either. The retarder can be stapled in before the sub floor goes down.
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Old 12-10-2008, 06:03 PM   #9
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Re: Vapour Barrier Between Garage And Living Area??


In order to put the vb to the warm side of the garage ceiling it would need to go down on top of the floor joists? We have in the past put 15 lb felt paper under the flooring but I am not sure how effective it is when you drive thousands of flooring staples through it.
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Old 12-13-2008, 10:55 AM   #10
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Re: Vapour Barrier Between Garage And Living Area??


Quote:
Originally Posted by big builder View Post
In order to put the vb to the warm side of the garage ceiling it would need to go down on top of the floor joists? We have in the past put 15 lb felt paper under the flooring but I am not sure how effective it is when you drive thousands of flooring staples through it.
I insulated new houses in Calgary for a couple of years...cantilevers and unheated garages are two of the most common areas where corners get cut, as far as providing an effective, continuous vapor barrier is concerned. In Canada, code compliance calls for R28 in these areas but installing batts after the fact (i.e. just prior to drywalling) is problematic. We were always provided with R20 batts for cantilevers in the house itself; these were "hooked" into an "L" shape and pushed into the joist space with a broom handle... The theory is that the 1/4 of the batt "hooked" will stand up to cover the rim joist and the remainder will cover the flat bottom (soffit) area. The problem is that in many cases, mechanicals and wiring make effective stuffing of this area impossible... vapor barrier? yeah right...
The more "conscientious" builders would have the framer poly the top of the joists prior to sheeting the floor...if this poly was present we used an "Olfa" knife to cut along the joists (as far back as you can reach) and dropped the tail of the poly over the top plate, then caulked the wall v/b over these "tails"...
I made deals on the side with a few of the builders to insulate and poly the rim joists and cantilevers (prior to the floors being sheeted), to my knowledge, I was the only one doing this; the drywall company I was subbing to was not happy when they found out about it!!! Regardless, this is the only way to attend to these "problem" areas properly.

As for garage ceilings?
The only way to do it right is to "drop" the ceiling and provide 5" heat runs to heat the entire space...
Dropping the ceiling allows for a continuous vapor barrier to be installed below the bottoms of the joists on the warm side of the insulation. Rim joists/garage wall (above the "drop") in this area should be treated the same as any other part of the house (R20/ continuous vapor barrier), the last step becomes batting the dropped ceiling with R28-24 prior to boarding/firetape. The drop should provide a minimum of 4" between the bottom of the floor joists and the vapor barrier to allow for effective circulation of the heat in the area.
This is the only effective way to do the job using common "production" residential insulating techniques/products. The HVAC company must be "on board" to accommodate for the additional forced air requirements to adequately heat this space as well. I never had a single "cold floor" call back, even at sustained temps of -40*C when these techniques were employed.
And yes...I admit that going behind the back of the company I was subbing to was wrong...I was young and stupid at the time.
The fact is though, that it was not a hard sell to convince the better builders that there was a definite value in "doing this right"...particularily the cantilevers. In the early days of "TJI" introduction, I encountered many a cantilever where the framer had blocked the joists at the top plate with chunks of TJI, leaving no access to the void behind, whatsoever...sometimes they'd get the sider/framer back to open the soffits from the outside...

...as often as not it was: "shoot, shovel and shut-up"

(this last is a quote from former Alberta Premier Ralph Klein, in reference to the BSE crisis of a few years back)

Cheers, Ron
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Old 12-16-2008, 12:12 PM   #11
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Re: Vapour Barrier Between Garage And Living Area??


Use vapor retarder both sides. buildingscience.com , RR-0410 and BSD-104. Look at local building code.
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Old 12-16-2008, 03:01 PM   #12
 
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Re: Vapour Barrier Between Garage And Living Area??


Quote:
Originally Posted by big builder View Post
In order to put the vb to the warm side of the garage ceiling it would need to go down on top of the floor joists? We have in the past put 15 lb felt paper under the flooring but I am not sure how effective it is when you drive thousands of flooring staples through it.
If your mechanical attachments are in the top of the joists, it will not matter as that "hole" will never be exposed to air.
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Old 12-16-2008, 03:05 PM   #13
 
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Re: Vapour Barrier Between Garage And Living Area??


Double vapor barriers will trap condensation because there is no such thing as a vapor barrier.

Vapor retarder? Yes.

Vapor barrier? NO.
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Old 12-22-2008, 05:06 PM   #14
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Re: Vapour Barrier Between Garage And Living Area??


Whew....


I don't really know where to go with this.

I think I would prefer to just spray foam the entire floor....but I am not a fan.

We never bat rim joist cavities was always have these foamed. Just seems to work way better and it fast.

Would I be correct in say that a sheet of 6 mil poly will no penetrations
is a vapour barrier?

Also, just my 2 cents but it seems like a bad idea to have poly on top and bottom of floor joists?
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Old 12-22-2008, 05:31 PM   #15
 
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Re: Vapour Barrier Between Garage And Living Area??


Quote:
Originally Posted by big builder View Post
Whew....


I don't really know where to go with this.

I think I would prefer to just spray foam the entire floor....but I am not a fan.

We never bat rim joist cavities was always have these foamed. Just seems to work way better and it fast.

Would I be correct in say that a sheet of 6 mil poly will no penetrations
is a vapour barrier?

Also, just my 2 cents but it seems like a bad idea to have poly on top and bottom of floor joists?

Poly on top and bottom=condensation>rot.

Poly is as good a retarder as any.
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Old 12-22-2008, 09:33 PM   #16
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Re: Vapour Barrier Between Garage And Living Area??


Quote:
Originally Posted by big builder View Post
Whew....


I don't really know where to go with this.

I think I would prefer to just spray foam the entire floor....but I am not a fan.

We never bat rim joist cavities was always have these foamed. Just seems to work way better and it fast.

Would I be correct in say that a sheet of 6 mil poly will no penetrations
is a vapour barrier?

Also, just my 2 cents but it seems like a bad idea to have poly on top and bottom of floor joists?
Why not a fan?? Seems as if poly spray foam would solve all your problems. Foam even seals the gas

And why in the heck do you keep coming back to the vapor barrier on the cold side Ever see what a PB&J sandwich looks like if left too long in a zip lock?

Last edited by davitk; 12-22-2008 at 09:38 PM.
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Old 12-23-2008, 09:45 AM   #17
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Re: Vapour Barrier Between Garage And Living Area??


From personal experience......not a good vapour retarder no matter what people say. I have over $30 000 dollars worth in my personal house and I still run gable fans ( in the partial attic). Hot roofs suck.

What do you mean bu poly spray foam?? I don't think y ou can do both.....double vapour right?

Unless you do what terrorron said, which is an excellent idea. sadly we don't always have enought headroom to make that happen. I guess the next best thing is too apply the vapour barrier before the subfloor goes on. I guess it's not considered proper practice but we have been putting the vapour barrier on the underside of the joists.
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Old 12-23-2008, 12:14 PM   #18
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Re: Vapour Barrier Between Garage And Living Area??


Quote:
Originally Posted by big builder View Post
From personal experience......not a good vapour retarder no matter what people say. I have over $30 000 dollars worth in my personal house and I still run gable fans ( in the partial attic). Hot roofs suck.

What do you mean bu poly spray foam?? I don't think y ou can do both.....double vapour right?

Unless you do what terrorron said, which is an excellent idea. sadly we don't always have enought headroom to make that happen. I guess the next best thing is too apply the vapour barrier before the subfloor goes on. I guess it's not considered proper practice but we have been putting the vapour barrier on the underside of the joists.

???

Poly = polyurethane = closed cell.

Check out this link. http://www.sprayfoam.org/index.php?page_id=229
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Old 12-23-2008, 02:25 PM   #19
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Re: Vapour Barrier Between Garage And Living Area??


Sometimes I just over think things.

I love the stuff in crawlspaces, rim joists, and places where you just can't realistically use anything else,

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