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Discussion Starter · #1 ·
I will be building my own home. I will be using 2x6 24" on center for the outer walls. The inside walls will be 2x4 16" on center, but no spray foam, so not worried about them.
I will be using closed cell spray insulation but not sure how to proceed with the rough-in for the electrical and do not want to completely enclose my wiring in spray foam.
Can I spray the insulation, then cut a channel of 3/4" radius to run the wires?
This would place the wires between the foam and the drywall.
As there needs to be some wire slack at the outlet box, I would want to carve out some of the foam above the outlet for the slack as well.
 

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Install your cabling as you would normally.
You can spray over the cables after the rough inspection.
 

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Have you priced out the foam option? Often time that cost makes the foam a no go. Also, rigid foam is normally limited to 2" to 3" max per installation, meaning to applications and spray foam is not DIY friendly.

An alternative which is very DIY would be a serious effort to caulk all stud cavities to match the air sealing benefits of spray foam. Then fill those 5.5" cavities with r-23 Roxul comfort batts, also very DIY friendly.

Done in half the time as what you describe and no conflict with any other rough-in steps.

Bud
 
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It's normal for cables to end up fully encased in spray foam. You can cut
out the insulation to avoid that if you wish, but it's required that cables be
back 32mm ( 1 -1/4") from the back of the drywall or other finish. This is
based on CEC but I'd be surprised if the NEC does not have a similar
requirement.
Code Ref: 12-516(1)
 

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Discussion Starter · #6 ·
Install your cabling as you would normally.
You can spray over the cables after the rough inspection.
Having my wires encased in the foam is what I am trying to avoid. I want to pre-stage to make getting wires in and out easier.
 

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Discussion Starter · #7 ·
Why would you build 24" OC, I have never seen that, not a great place to save $200.
24" on center is perfectly fine for exterior walls when building a house like mine with no attic and single floor. More stable, stronger, and energy efficient than 2x4 16" on center.
 

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Discussion Starter · #8 ·
It's normal for cables to end up fully encased in spray foam. You can cut
out the insulation to avoid that if you wish, but it's required that cables be
back 32mm ( 1 -1/4") from the back of the drywall or other finish. This is
based on CEC but I'd be surprised if the NEC does not have a similar
requirement.
Code Ref: 12-516(1)
I will double check the NEC and state requirements, but if the case, then will use conduit. Thank you for pointing that out.
 

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Discussion Starter · #10 ·
Have you priced out the foam option? Often time that cost makes the foam a no go. Also, rigid foam is normally limited to 2" to 3" max per installation, meaning to applications and spray foam is not DIY friendly.

An alternative which is very DIY would be a serious effort to caulk all stud cavities to match the air sealing benefits of spray foam. Then fill those 5.5" cavities with r-23 Roxul comfort batts, also very DIY friendly.

Done in half the time as what you describe and no conflict with any other rough-in steps.

Bud
I was not aware of the max amount of spray foam insulation that can be applied to be effective.
It is already planned to seal everything with caulk or silicon(where it will be better but still researching that). I know some things like framing, electrical rough-ins and plumbing rough-ins, but still plenty of research to do.
I will review the code and adjust accordingly. Thank you.
 

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Can I spray the insulation, then cut a channel of 3/4" radius to run the wires?
This would place the wires between the foam and the drywall.
Wires in a shallow groove ( channel) require nail protection. NEC 300.4(F)

(F) Cables and Raceways Installed in Shallow Grooves. Cable or raceway-type wiring methods installed in a groove, to be covered by wallboard, siding, paneling, carpeting, or similar finish, shall be protected by 1.6 mm (1∕16 in.) thick steel plate, sleeve, or equivalent or by not less than 32-mm (11∕4-in.) free space for the full length of the groove in which the cable or raceway is installed.
Exception No. 1: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing.
Exception No. 2: A listed and marked steel plate less than 1.6 mm (1∕16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted.
 

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24" on center is perfectly fine for exterior walls when building a house like mine with no attic and single floor. More stable, stronger, and energy efficient than 2x4 16" on center.
We build all our houses 2x6 exterior 16" OC 2x4 interior. One builder asked us to build the interior walls 24" OC, he would have saved 14 studs on the main floor.
 

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Discussion Starter · #13 ·
Why are you concerned about getting the wires out?
Install them and you are done.
My state has requirements that if I want to re-sell a house I built, it needs to meet certain requirements. While this is not a requirement in this case, it can make for a good selling point later on and is easy to do during construction phase. If you knew you would not have to fight with insulation to run wires or pull out wires, can you say that is not an advantage. However, that is my brain working in the future. I am building the house to include what I would want, and this will make life easier for the later wire runs I will do for my fiber network.
 

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My state has requirements that if I want to re-sell a house I built, it needs to meet certain requirements. While this is not a requirement in this case, it can make for a good selling point later on and is easy to do during construction phase. If you knew you would not have to fight with insulation to run wires or pull out wires, can you say that is not an advantage. However, that is my brain working in the future. I am building the house to include what I would want, and this will make life easier for the later wire runs I will do for my fiber network.
It would be the only house ever built (except for conduit systems) that was designed for later wire changes. In fact code requires wires be stapled to studs that makes this idea virtually impossible.

If this is truly what you want then conduit is the way to go. However even the conduit may not be going where you want it in the future.
 

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Discussion Starter · #16 ·
It would be the only house ever built (except for conduit systems) that was designed for later wire changes. In fact code requires wires be stapled to studs that makes this idea virtually impossible.

If this is truly what you want then conduit is the way to go. However even the conduit may not be going where you want it in the future.
yeah, there is the staple on the stud for the extra romex. Well, as I really want the conduit for electronics wires, I can create a conduit for just that a bit higher on the walls. Will have to go back over my initial plans.
 

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What I meant was 2 applications (not to). Not a pro on foam but it needs to cure and too thick and that does not happen. It also generates a lot of heat, search homes burning down due to spray foam not being installed correctly.

Not sure where you are building but some minimum required r-values cannot be met with a single install, although an inspector might let it pass. But the results would be no better than the caulk and batt I described.

Bud
 
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