Bedroom addition above the garage.

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Posted by: from Toronto
5/17/2016 at 2:33:59 PM


I hired a contractor for a big reno on my house. Part of the reno is building a bedroom above a pre-existing garage. There is wood frame on the brick/concrete wall of the garage.

My dad said there should be some kind of plastic or foam barrier between the wood and concrete to prevent condensation. Is this true?

I asked my contractor and he said:

"That is true to new builds. This is going onto an existimg structure and its not on a foundation wall. Its on a brick wall".

I have photos for clarity.

Bedroom addition above the garage.
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Date/Time5/17/2016 at 3:03:06 PM

Depends on your local building codes. You need to always have a vapour/moisture barrier between each floor regardless. Hope all works out. Tell the builder to stop till he complies as a clients request. There has to be permits in place and hopefully your walls are all good.


Ian Byng-Jewett

All That Contracting

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Yuri from AIMG Inc in Richmond Hill
Date/Time5/17/2016 at 3:25:10 PM


Plastic or foam barrier is a MUST. Make sure it is fixed otherwise moisture will cause damage to the wood supporting all structure.

Best regards,


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Date/Time5/17/2016 at 3:44:36 PM

This type of project requires a building permit, if you are not confident in your builder or the work being done it is always a good idea to consult with the architect or building inspector on the project. They are the ones responsible to design and ensure the building complies with OBC regulations.

That being said, I am not aware of any time it is okay for wood to be in direct contact with concrete as the wood will absorb moisture and rot over time.

Call the architect that signed off on the drawings or the building inspector if your not sure if its done correctly or not.

Good Luck!

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Date/Time5/17/2016 at 4:03:16 PM

You should consult your engineer who did the drawings for you as well as if that thing include in the code the inspector will not pass it and he should ask the contractor to make it done probably?

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Date/Time5/17/2016 at 8:30:40 PM

I have to agree with the posts.

However, I always install a moisture barrier between wood and concrete. Or wood and concrete block.

Hope this helps,

James Fram

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Date/Time5/18/2016 at 10:00:00 PM

Anytime wood is placed against a moisture retaining item such as masonry or concrete a vapour barrier needs to be used. Non pressure treated wood will only last years before showing signs of deterioration and a engineered joist like what is being used has an OSB core that is never good to let moisture in contact with.

Hope this is helpful,

Joel Dunkley

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Steve from Proka in Montreal
Date/Time5/19/2016 at 8:52:02 AM

Ridiculous, vapour barrier a must!!

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