Seal vapour barrier around ceiling fan box.

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  #1  
Old 05-30-16, 10:14 PM
A
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Question Seal vapour barrier around ceiling fan box.

I would like to install a ceiling fan in the master bedroom of our new townhome (constructed in 2014). I bought a Westinghouse Saf-T-Brace with my ceiling fan and would appreciate any adivce about how to install it while maintaining the integrity of the vapour barrier.

When taking down the existing light fixture, I discovered that the light fixture was mounted to a yellow plastic junction box. It appears that the holes in the junction box where the wires enter may be sealed on the outside of the box with some form of black foam sealant. I can also see that there is what appears to be 6 mil poly vapour barrier above the drywall on the ceiling. I poked my head up into the attic for the first time and discovered that we have about 14 inches of blown-in fibreglass insulation and that the ceiling and roof is constructed using 2x4 engineered trusses. Getting to junction box from the attic would be possible but quite difficult, and would likely mean moving quite a bit of the insulation around.

The instructions that come with the Saf-T-Brace simply say "Clear the area of insulation" and don't mention vapour barriers at all. I've Googled extensively but found very little information about ceiling fans and vapour barriers. Are there any best practices to follow to maintain the integrity of the vapour barrier when installing a retrofit ceiling fan support?

Thanks!
 
  #2  
Old 05-31-16, 04:49 AM
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Hi al and welcome to the forum
The vapor barrier is less of an issue than the air barrier. Lots of air can leak through a small hole, carrying moisture with it, while a hole in a vapor barrier is usually protected by drywall. With a VB it is a % issue. With 1% of the VB being holes you still have 99% protection. Unless those holes are also air leakage paths.

A small rake will move the insulation around, be neat, and then be sure the install is air sealed and you will be fine.

Bud
 
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Old 05-31-16, 08:55 AM
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Thanks Bud.

One more question then: What type of sealant should I use to seal the small gaps around the outside of junction box and around the bushings where the wires enter?
 
  #4  
Old 05-31-16, 09:12 AM
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Can foam or caulking. Just don't get a bunch of it inside the box.

Bud
 
  #5  
Old 06-15-16, 04:26 PM
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I know that my reply is a little late, but I went with a double-gang vapour barrier device box. I cut holes for the wires and support arms and sealed it all with tuck tape. I picked up some acoustical caulking too just in case I needed it, but found that I was able to make it air tight with just the tape. And it was probably less messy too. Thanks for your advice!
 
 

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