# Air sealing around electrical boxes/outlets



## spitz1234 (Jan 1, 2019)

Foam insulation gaskets

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## SeniorSitizen (Sep 10, 2012)

Electrical boxes in a wall are similar to Belly Buttons, there's innies and outties. If cold air is coming into the room through the box it's originating from somewhere else. If air is going out of the box it's exiting somewhere else. Look at the big picture to stop the air flow. In my opinion, attempting to seal those boxes is similar to placing a Styrofoam cover on a hydrant on the side of the house to prevent freezing.


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## carpdad (Oct 11, 2010)

I used to seal all holes and joints with caulk, can foam, foil tape, but now i think that was waste of material and effort. Should have sealed the exterior sheathing against air and forget the boxes. If plywood, just the joints and 4 sides of the stud bay. If 1x boards, 1/2" foam board. If retrofitting, with those plastic boxes, caulk at the cable openings.


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## jbrah (May 29, 2018)

carpdad said:


> I used to seal all holes and joints with caulk, can foam, foil tape, but now i think that was waste of material and effort. Should have sealed the exterior sheathing against air and forget the boxes. If plywood, just the joints and 4 sides of the stud bay. If 1x boards, 1/2" foam board. If retrofitting, with those plastic boxes, caulk at the cable openings.


The stud bays are sealed - foam board cut to fit each bay with spray foam around the perimeter, and caulk where the studs meet top and bottom plates.

So the concern isn't so much about outside air getting into the stud bays (though of course that could happen over time), but about room air getting into the stud bays, which would be an unnecessary loss of conditioned air, but also a potential condensation concern in the winter since the bays are air sealed (i.e., warm humid interior air gets into stud bay and has no drying path to the exterior).


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## SeniorSitizen (Sep 10, 2012)

How many inches of drywall didn't get sealed to the top of the top plate? Calculate every exterior wall 1 side and every interior wall both sides that cold attic air can travel down to those electrical boxes, switches and or out into the room at floor level.


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## jbrah (May 29, 2018)

SeniorSitizen said:


> How many inches of drywall didn't get sealed to the top of the top plate? Calculate every exterior wall 1 side and every interior wall both sides that cold attic air can travel down to those electrical boxes, switches and or out into the room at floor level.


Actually, I'm remodeling a particular room, and I am going to seal the drywall to the framing.


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## Nealtw (Jun 22, 2017)

jbrah said:


> Actually, I'm remodeling a particular room, and I am going to seal the drywall to the framing.


 If you are not using a VB just caulk the holes in the outside of the box and exterior boxes have a perimeter gasket. 

If the attic and floor is sealed properly there is no problem with interior walls.


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## jbrah (May 29, 2018)

Nealtw said:


> If you are not using a VB just caulk the holes in the outside of the box and exterior boxes have a perimeter gasket.
> 
> If the attic and floor is sealed properly there is no problem with interior walls.


What's a VB?

My plan is to spray foam the knockouts on the back of the boxes (where the wires enter box). Once drywall is up, I was thinking I'd use spray foam to fill the small gap between the drywall and perimeter of box. Then outlet gasket under the cover plate.

How is that perimeter gasket installed? Seems if I were to put that around the box, then when I'm cutting out the drywall with a rotozip, the bit would chew up the gasket? I guess the gasket is thick enough that the bit doesn't go all the way through it, so you still get an air seal?


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## Nealtw (Jun 22, 2017)

jbrah said:


> What's a VB?
> 
> My plan is to spray foam the knockouts on the back of the boxes (where the wires enter box). Once drywall is up, I was thinking I'd use spray foam to fill the small gap between the drywall and perimeter of box. Then outlet gasket under the cover plate.
> 
> How is that perimeter gasket installed? Seems if I were to put that around the box, then when I'm cutting out the drywall with a rotozip, the bit would chew up the gasket? I guess the gasket is thick enough that the bit doesn't go all the way through it, so you still get an air seal?


 Those boxes come like that the drywall sits against the gasket. 

Watch the video here. 

https://www.shdelectric.ca/archives/1240


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## That Guy (Aug 19, 2017)

SeniorSitizen said:


> Electrical boxes in a wall are similar to Belly Buttons, there's innies and outties. If cold air is coming into the room through the box it's originating from somewhere else. If air is going out of the box it's exiting somewhere else. Look at the big picture to stop the air flow. In my opinion, attempting to seal those boxes is similar to placing a Styrofoam cover on a* hydrant* on the side of the house to prevent freezing.


That hydrant you speak of is called a spiget:wink2:


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## SeniorSitizen (Sep 10, 2012)

That Guy said:


> That hydrant you speak of is called a spiget:wink2:


When someone determines how to spel it i'l use that word more.:biggrin2:


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## That Guy (Aug 19, 2017)

SeniorSitizen said:


> When someone determines how to spel it i'l use that word more.:biggrin2:


https://www.beedictionary.com/common-errors/spicket_vs_spigot


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## jbrah (May 29, 2018)

Nealtw said:


> Those boxes come like that the drywall sits against the gasket.
> 
> Watch the video here.
> 
> https://www.shdelectric.ca/archives/1240


I get it, thanks. Wish I knew about these before I installed all the electrical boxes!


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## carpdad (Oct 11, 2010)

First seeing boxes like those. Does that mean the outlets can be installed without the ground pigtail? What info I have is fairly old. I thought the inspectors wanted to see the ground wire out of the outlets?


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