Vapor barrier boxes

[pmoney44]

Good evening,

State of Massachusetts

I’ve been seeing a lot of these electrical boxes with so called vapor barrier.
They are plastic boxes guessing for residential use but have a gasket around them. They seem to be very expensive compared to regular plastic boxes. In the state of Massachusetts does anyone know if these are a new code requirement for New residential construction or just a new way for suppliers to increase cost in the industry?

 

[JFElec]

https://www.mass.gov/files/document...-towns-adoption-by-community-map-and-list.pdf




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[JFElec]

Not new at all, and not a ploy— it’s just a lot of cities/towns haven’t adopted stretch code.


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[goldstar]

Just a side bar, they’re not a bad idea and I don’t have a problem using them. However, there are some instances (like kitchens) where I like to use adjustable boxes because the back-splashes are usually tiled. Using extension collars can sometimes be a real PITA.

That said, I’m told by some of my colleagues that there are some towns here in NJ that are requiring them. Not sure what Code they are citing but some EI’s like to find obscure Codes just to break chops :happyyes:

 

[dkidd]

It's from the IECC.

 

[goldstar]

There’s the obscure Code !!! It’s hard enough trying to keep up with the NEC and then an EI finds this one just to let you know he’s “up on the Codes”. :rant:

 

[dkidd]

There’s the obscure Code !!! It’s hard enough trying to keep up with the NEC and then an EI finds this one just to let you know he’s “up on the Codes”. :rant:

That's PE.

 

[Knuckle Dragger]

My experience so far in Massachusetts vapor barrier boxes are not required in remodels ( I'm not talking additions) and where closed cell spray foam in used.

 

[pmoney44]

My experience so far in Massachusetts vapor barrier boxes are not required in remodels ( I'm not talking additions) and where closed cell spray foam in used.

My application would be for a new construction home.

 

[Knuckle Dragger]

My application would be for a new construction home.

If the GC is using closed cell spray foam insulation in the walls when you don't need vapor barrier boxes. If they are using fiberglass then you will need vapor barrier boxes.

 

[lordofthisworld]

Good evening,

State of Massachusetts

I’ve been seeing a lot of these electrical boxes with so called vapor barrier.
They are plastic boxes guessing for residential use but have a gasket around them. They seem to be very expensive compared to regular plastic boxes. In the state of Massachusetts does anyone know if these are a new code requirement for New residential construction or just a new way for suppliers to increase cost in the industry?

What I understand they only have to be installed on the outside walls.

 

[kwired]

There’s the obscure Code !!! It’s hard enough trying to keep up with the NEC and then an EI finds this one just to let you know he’s “up on the Codes”. :rant:

Unless the inspector is a "combination inspector" IMO this is not a concern for strictly an EI. He may make a suggestion that another inspector is not going to accept something though.

If the GC is using closed cell spray foam insulation in the walls when you don't need vapor barrier boxes. If they are using fiberglass then you will need vapor barrier boxes.

Seems to me they are only required if the box is penetrating the "vapor barrier". Spray foam insulation - the vapor barrier is behind the box (most of the time anyway)

 

[Knuckle Dragger]

Unless the inspector is a "combination inspector" IMO this is not a concern for strictly an EI. He may make a suggestion that another inspector is not going to accept something though.

Seems to me they are only required if the box is penetrating the "vapor barrier". Spray foam insulation - the vapor barrier is behind the box (most of the time anyway)

I'm not 100 percent sure but i believe it it is 2x6 construction with fiber glass insulation you may not need vapor barrier boxes either.
Maybe someone here knows for sure.

 

[pmoney44]

I'm not 100 percent sure but i believe it it is 2x6 construction with fiber glass insulation you may not need vapor barrier boxes either.
Maybe someone here knows for sure.

I’m under the impression they are needed in outside walls and ceilings. A colleague of mine was called out on it in another town in Massachusetts. I’m guessing he was referred to the building code. But I still haven’t received exact clarification. Guess I’ll have to contact AHJ.

 

[pmoney44]

I'm not 100 percent sure but i believe it it is 2x6 construction with fiber glass insulation you may not need vapor barrier boxes either.
Maybe someone here knows for sure.

Got me???

 

[kwired]

I’m under the impression they are needed in outside walls and ceilings. A colleague of mine was called out on it in another town in Massachusetts. I’m guessing he was referred to the building code. But I still haven’t received exact clarification. Guess I’ll have to contact AHJ.

Where else would they apply to?

This is not an NEC requirement, it would be an energy code issue I would think. Probably not the only way to comply, but likely the easiest way to comply.

 

[Adamjamma]

I think too many inspectors watched Holmes on Homes and decided that should be correct. But, in the show, it looks like Holmes uses a vapor barrier in every single room, and uses tape over the staples etc... then wraps plastic around the boxes as well, taping that plastic to his barrier, and the only times he did not do that was when he used spray foam...

AgIn, that was certain places in Canada. Not USA.

 

[Knuckle Dragger]

I in gut jobs (remodels) I typically don't install VB boxes, but in all other new work yes, unless closed cell is used.
If closed cell is used in the roof rafters then you don't need the vapor barrier boxes in the ceiling.
I don't have code references this is just what I have figured out throughout the years through the GC and inspectors.
When all else fails ask the AHJ.

 

[bullheimer]

From my latest set of prints, I'm in Washington State: Electrical and Communication Boxes: THE AIR BARRIER SHALL BE INSTALLED BEHIND ELECTRICAL OR COMMUNICATION BOXES OR AIR SEALED BOXES SHALL BE INSTALLED.
What this means, i am still trying to figure out. I don't believe it is required by the Electrical AHJ but it is spec'd out so I am trying to see if it is enforced by a BUILDING inspector and if i can delete it. Platt employee gave me a price of $4/box then when i went in his boss showed me a picture of a box with a flange and gasket and told me No, the price is $14. Then he dropped it down to just below $9 each when i said i might need 30 of them. Now please note, the quote from the print, says "Air Barrier" not Vapor Barrier, just to add to the confusion. So... welcome back from the dead, OP.

 

[wwhitney]

Yes, the entire 2018 discussion should be referring to air barriers, not vapor barriers.

Every building needs multiple control layers, i.e. a continuous shell surrounding the interior space that controls exchange of some quantity. E.g. thermal (insulation), air infiltration (air barrier), water vapor exchange (vapor barrier if appropriate), liquid water (weather resistive barrier and/or rain screen), bulk water (siding).

It's up to the designer to decide where the air barrier is. On walls, often a good choice is the exterior sheathing, with taped seams and careful connection to the foundation and to the top air barrier (be it ceiling drywall, roof sheathing and a sealed attic, or whatever). That case has no effect on electrical boxes, they are inside the air barrier already.

Another option is to use the interior drywall on exterior walls as the air barrier (although things get tricky at intersecting interior walls). If you do that, then you need air barrier electrical boxes, as the box is interrupting the air barrier.

Cheers, Wayne