# Vapor barrier for canadian garage that wont be heated often/not too long?



## PatInsulator (Sep 24, 2019)

So.. as the title of this thread states, I am about to start a project. My garage is 30x25 and I want to insulate it, but it will only get heat for 6-9hours per week. 

Would that little heat create enough moisture to cause mold and stuff? I am thinking of using fiberglass batt insulation for the walls covered with either drywall or 7/16" osb sheathing and cellulose blown insulation in the ceiling with 7/16" osb sheathing.. i will use spmething like an industrial heater whenever I do heat it up.. i have yet to figure out what ill do for the overhead doors..


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## user_12345a (Nov 23, 2014)

Heat doesn't create moisture - you have to have a moisture source for that.

Even without moisture, a air/vapor barrier will make batt insulation more effective.

Only concern - if you park cars in the garage and it's attached to the house, sealing it up could trap car exhaust and some of it can enter the house.


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## 660catman (Aug 25, 2019)

For the price of vapour barrier don’t skimp on the build. Snow covered car inside when you heat garage will create moisture. 


Retired guy from Southern Manitoba, Canada.


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## PatInsulator (Sep 24, 2019)

Okay, i suppose I should expand a bit.. the garage is not attached to the house, and I do not park my cars in there. I will only heat it up when I am using the garage as a jam spot with my band, and when Ill be using it to fix my snowblower or do oil changes on cars and whatnot..


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## PatInsulator (Sep 24, 2019)

And the reason why i kinda want to skip on it is because i inherited the garage when buying the property and the previous owner has already nailed osb to the bottom chords of my roof trusses and there is a bunch of light fixtures and whatall.. kinda dont want to remove and reinstall everything for the vb.. or try to mess around in between the webs and all of that


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## 660catman (Aug 25, 2019)

Sounds like you’ve made up your mind already. Sorry, but I’d be ticked if I bought a place with “finished” garage that smells like mould and find out no vapour barrier was installed. A lot more work with walls finished too!! 


Retired guy from Southern Manitoba, Canada.


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## Nealtw (Jun 22, 2017)

PatInsulator said:


> And the reason why i kinda want to skip on it is because i inherited the garage when buying the property and the previous owner has already nailed osb to the bottom chords of my roof trusses and there is a bunch of light fixtures and whatall.. kinda dont want to remove and reinstall everything for the vb.. or try to mess around in between the webs and all of that


 The attic will want its soffet and high vents , you would air seal the osb from above before the insulation. When plans change you would just add drywall over the OSB.


Always plan on plans changing. Always do it like it was going too have a suite in it on day.


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## PatInsulator (Sep 24, 2019)

Would it work to use vb on the walls, but not in the attic? Does the soffit vents air flow not allow any moisture to dry out?


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## PatInsulator (Sep 24, 2019)

Or... would it be problematic to staple the vb to the ceiling osb thats already there and then cover that with drywall?


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## Nealtw (Jun 22, 2017)

PatInsulator said:


> Or... would it be problematic to staple the vb to the ceiling osb thats already there and then cover that with drywall?


No that would be easy enough, you would still have to seal anything like light fixtures from above.


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## PatInsulator (Sep 24, 2019)

That sounds like my best course of action then! Thank you all for your insight!


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## Nealtw (Jun 22, 2017)

PatInsulator said:


> Would it work to use vb on the walls, but not in the attic? Does the soffit vents air flow not allow any moisture to dry out?


Yes it does but you want to do all the cheap stuff to keep the moisture out of there.


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## PatInsulator (Sep 24, 2019)

Whats "all the cheap stuff" to keep moisture out of there? And what would the good stuff be?


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## user_12345a (Nov 23, 2014)

vapour barriers do improve insulation performance whether or not moisture is an issue - stop the air movement.

with a insulated attic you will need to add in ventilation.


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## Nealtw (Jun 22, 2017)

PatInsulator said:


> Whats "all the cheap stuff" to keep moisture out of there? And what would the good stuff be?


 Cheap and good are the same thing, Vapour barrier.


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