Minimum wall thickness for Romex?

kwired

Electron manager
Location
NE Nebraska
To clarify, this was a theoretical when I asked about drywall on either side. I said that because I didn't want to take the time to explain the actual scenario. Here goes:

I have a situation where the builder has attached plywood to the underside of roof trusses in order to create a ceiling with a tight air barrier. He will then fur down with 2x2's to attach his drywall lid. He wants to use the small space in between as a chase for wires. 2x2 is ideal because he has standard double top plate so doesn't want to drop too far.

It's a tight attic above, so I suppose you could say the wires are safe on the side of things anyway?

this is where this question originated. Thanks for the replies
That IMO a lot like furring a basement wall with 2x2's. No nails or screws are likely to ever be an issue from "the back side" and can be disregarded.
 

jap

Senior Member
Yes longer screws needed, not so much because you need deeper penetration in the framing member though, you need to penetrate the first layer of drywall before reaching the framing member.
Larry said, "Laminating a ceiling with a new drywall layer, such as when covering a textured one, often requires much longer screws"

K-wired said "Yes longer screws needed, not so much because you need deeper penetration in the framing member though, you need to penetrate the first layer of drywall before reaching the framing member".

Jap says ...... :unsure: aren't you both simply describing the same thing?,,,, a longer screw? :)
 

retirede

Senior Member
Location
Illinois
Larry said, "Laminating a ceiling with a new drywall layer, such as when covering a textured one, often requires much longer screws"

K-wired said "Yes longer screws needed, not so much because you need deeper penetration in the framing member though, you need to penetrate the first layer of drywall before reaching the framing member".

Jap says ...... :unsure: aren't you both simply describing the same thing?,,,, a longer screw? :)
Here is my interpretation:

Larry is concerned that the rocker will grab any screw as long as it’s way longer - the longer the better. Possibly hitting wire that is properly installed >= 1-1/2” from the surface of the framing.

Kwired is saying the while a longer screw is warranted, a proper screw should be chosen that does not penetrate the framing member deeper than the screws used with a single layer of rock.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
How thick is the plywood, and can you staple to it without fully penetrating it (maintaining the air barrier)? If so, just staple the wire at least 1-1/4" from the edge of the 2x2s.

Cheers, Wayne
 

mwm1752

Senior Member
Location
Aspen, Colo
You can place a secure a support to each stud & secure the NM to it - a piece of wire can be used for the support. Just make sure the NM is secured away from the stud per code
 

kwired

Electron manager
Location
NE Nebraska
Here is my interpretation:

Larry is concerned that the rocker will grab any screw as long as it’s way longer - the longer the better. Possibly hitting wire that is properly installed >= 1-1/2” from the surface of the framing.

Kwired is saying the while a longer screw is warranted, a proper screw should be chosen that does not penetrate the framing member deeper than the screws used with a single layer of rock.
Correct. Adding an additional 1/2" layer should really only need screws 1/2" longer that what was used in the first layer. Penetration into framing member would still be the same.
 

jap

Senior Member
Correct. Adding an additional 1/2" layer should really only need screws 1/2" longer that what was used in the first layer. Penetration into framing member would still be the same.
Good luck with that. :p

Jap>
 

kwired

Electron manager
Location
NE Nebraska
Good luck with that. :p

Jap>
What is needed vs what actually happens doesn't always happen.

1-1/4 from face of stud - hopefully most of us have learned some places that doesn't matter, like where you know cabinets will be hanging - avoid running cables in that area as much as possible. If you must run cable there, get it above or below the elevation where fastening commonly occurs at the very least you might save yourself some re wiring.
 

jap

Senior Member
Agreed.

What really gets your goat is when you do your own remodel, put nail plates over everything needed for protection, then, cuss yourself when you run into the nail plates while installing the cabinets, base, or crown molding.

JAP>
 
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