# Vapour Barrier Sealing Around Heat Duct



## mattpalmeris (Nov 17, 2011)

I have a situation where I'm doing a reno on a house with the top floor cantilevered over the bottom by 2 feet. The Hvac duct for the top floor travel tucked into the floor joists and out to the floor registers. All the other joist cavities are sealed with VB but the ones with the ducts.

The Inspector is calling for the sections with ducts to have VB as well. What is the prescribed method as I don't think tape and VB would stand up to the heat the pipe is putting out. 

Any advise would be appreciated.


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## Windows on Wash (Aug 30, 2011)

What type of heating system it is?

Can you just insulated with a mineral wool and cut piece of drywall to fit the joist cavity and seal with intumescent if you are worried.


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## mattpalmeris (Nov 17, 2011)

Windows on Wash said:


> What type of heating system it is?
> 
> Can you just insulated with a mineral wool and cut piece of drywall to fit the joist cavity and seal with intumescent if you are worried.


Its a Natural Gas forced air system. As for the Drywall I don't think it accomplishes what the inspector is looking for in terms of a vapour barrier.


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## Windows on Wash (Aug 30, 2011)

Neither does plastic melted to the duct work line.

I am sure one of the HVAC guys can correct me if I am wrong but I seem to recall that output temps can be north of 140 if I am not mistaken. That is certainly close enough to mess with plastic.


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