I am doing a living room remodel, I stripped everything down to the studs, did plumbing and electrical and now it's time for insulation.
I have a guy that will spray foam all the studs for a good price.
Can you even use spray foam around the wires or will they get too hot and cause a fire?
I dnno
do you intend to use flammable foam?
I dunno. It's whatever is commonly used.
I'm assuming closed cell foam, that's all I know.
As long as you're maintaining proper spacing between cables (basically don't put more than 3 NM cables under 1 staple or through one hole) you're fine. Source:
NEC334.80, 310.15(B)(2)(a)
so I can do the same in the OP picture? You sure? all of those wires together covered in foam?
In short, yes, however... Coming down into the panel like in the image you're gonna wanna put up a nailer board so you have enough space to separate cables and staple them in pairs/triples. Basically you don't want a big wad of cables all grouped together running down the studs. Everywhere else just make sure wires along studs or going through drilled holes aren't in groups of more than 3.
The long story short of why is that your breakers are sized off of wires that can get as hot as 60C before melting, but the wires in NM are rated for 90C. So although it's true that insulation around wires does cause more heat, and that by code you need to derate them, with NM you start with a lot of "headroom" and it doesn't become an issue until you start cramming 4 wires under a single staple or a single drilled hole.
>in the OP picture
If you have a service panel in your living room, there are more fundamental problems with your home.
Also, why are you insulating interior walls? If you tore the exteriors back to the sheathing, well yeah you wanna insulate that. But put back the type of insulation you found there. Otherwise things can get weird.
Your pic looks like imminent danger but I don't dabble in the spooky electrical arts
Man I just fireproofing to a house I'm building and got the inspector to on my work but I just sprayed all the holes and openings through the boards that the cables were going through. That to me looks like complete overkill and a total waste of money considering all the cans you had to buy for that. I know every state has their own fire codes when it comes to buildings but I would have watched a few videos on how people do it first or just call your inspector up and ask and text him pictures, that's at least free and doesn't cost money to come to your site.
Why the frick exactly do you even want to do that? Just lift the wires up, spray, and rest the wires on the foam after it hardens.
The wires are stapled down if things were done correctly.
>It's correct to do things in such a way that you have to insulate your wires and make them overheat
Nope. If it was me I would rip out the staples and ensure the wires are able to be air cooled for the majority of their length
And if it was you you'd be throwing money/time down the drain needlessly. As I said in
, NM cables are rated up to 90deg, but the breakers are sized as if they were only 60deg C.
Do me a favor, grab your copy of the NEC (you do have one handy right?) Look up 334.80, and do the derating calculations indicated.
What you'll find is that heating doesn't become an issue (ie, drop the ampacity of your conductors below the breakers size (20A for 12awg)) until you begin cramming 4 or more cables together in one hole or staple.
Every modern house is has been done this way since spray insulation became common. And yet there's been no sudden uptick in electrical fires.
And also, a drywall screw nicking a conductor due to improper stapling is a MUCH more likely source of trouble than excess heat which the wires are rated to handle anyway.
>rated to handle
even if they're covered in spray foam and the foam expands thus compressing the wire insulation?
1) I've dug many-a-wire out of spray foam, it doesn't compress the outer sheathing at all near as I can tell.
2) It's a foam it fills space it doesn't really compress things anyway. If it fills the space it just oozes out of the stud bay. Even if it does expand aggressively enough that it /could/ squeeze things, it just takes the path of least resistance out the 14.5inch wide studbay its being sprayed in to.
2) Staples which are listed for holding multiple cables compress the cables to some degree, which is why we do derating calculations to account for the extra heat. And as I said, the conductors in NM cable are much more thermally resistant than what we assume when sizing breakers. So you have a fair amount of room to derate the conductor ampacity before it becomes anything to worry about.
>1) I've dug many-a-wire out of spray foam,
was it closed cell foam or open cell?
>2) Staples which are listed for holding multiple cables compress the cables to some degree, which is why we do derating calculations to account for the extra heat. And as I said, the conductors in NM cable are much more thermally resistant than what we assume when sizing breakers. So you have a fair amount of room to derate the conductor ampacity before it becomes anything to worry about.
yeah but they only compress the wire in a tiny section
the foam would compress the entire wire
Both but it's typically closed cell especially in exterior walls. It doesn't compress the cables because when it goes on it's a light airy liquid. It dries hard and kinda glues itself to sheathing so pulling wires out can be a pain in the ass but that's it.
As an example, I'll often leave wires loose in the wall so that I can come back during finish and cut in lights/receps so they're perfectly centered on cabinets, sinks, etc. Not only are the wires uncompressed when I come back, they haven't even moved. The foam doesn't even have enough force to shift a wire that's dangling in the stud bay. It just does what foam does and expands around everything.
I mean just think about it logically. You're acting like the foam is going into a sealed container and that it is going to expand and push on things like tree roots or ice or something. That's just not what happens. Think about how foam behaves. It's liquidy and expands to fill empty space. When it's filled all the gaps it doesn't suddenly start compressing inward, because it's got nothing to push against. It's in a wide shallow open container so it just expands out.
AND ANOTHER THING
Do you understand why compressing a wire is bad? It's not because you're limiting airflow, it's because compressing it strains the conductors and increases resistance. Ain't no way a liquid foam is compressing a copper wire to that extent.
>I'll often leave wires loose in the wall so that I can come back during finish and cut in lights/receps so they're perfectly centered on cabinets, sinks, etc
I'm putting in like 40 potlights, I'm going to have the wire dangling in the areas where the potlights will be
How do I create a void or something before the spray foam guy comes so I have enough room to install the potlight after the foam is installed?
>It's liquidy and expands to fill empty space.
Then why do people use low/no expansion foam around windows so they won't bow the window frame?
Also another question, sometimes I see spray foam installed only partially in the stud cavity and other times it fills the whole cavity?
Why is either of these ways done? Cost?
If it's only partially filled, wouldn't it just be cheaper to use batts to fill the stud cavity and get the same effectiveness of insulation?
doesnt the spray foam fill the entire stud cavity?
Just buy fibreglass batts, knauf or similar.
Cheaper and you can actually do modifications later in down the track without having to worry about hacking all the old foam out.
>gayfoam
enjoy huffing poisonous off-gasses for the next decade
it stops offgassing after a few days
> he actually believes this
LOL!!!
no guarantee if there's a problem with the batch, or the installer fricked up
just put 6 mil poly on the walls with tape before you drywall
problem solved
it's not good enough if it's offgassing
it's better to avoid altogether if sensitive, or pay for a reputable installer and hopefully it goes ok
>it's not good enough if it's offgassing
how would the VOCs make it through the poly and the drywall?
you think that counts as airtight?
if its taped properly
Yes sheets of plastic with a zillion staple holes and a trillion screw holes under constant vacuum of stack effect is totes air tight
Design any submarines lately?
The spray foam fad/scam is pretty much over.
I don’t see anyone recommending it except for spray foam installers that can’t do anything else.
A good proportion offgas significantly over time. You can get entire areas where the mix wasn’t exactly right and offgasses for years.
Of course, if there is a fire, I can’t imagine the kinds of shit it puts out. Significant hazard.
It derates all your wires. It keeps the heat in.
In the big picure, the fact that it locks all the stuff in resin makes the whole idea idiotic. Electricians should charge 10k to add a light switch since it’s
- a lot of extra work
- serves as a “stupid tax” for spray foam likers.
Construction gay here.
Use the old school bats.
If you use foam, and you ever need to get to some wires or pipes (which you will some day) you'll be cutting through hardened foam, hoping you don't nick a wire. Instead of just pulling the bat away doing your work and putting it back.
IDK why so many areas of home renovation, everyone wants to reinvent the wheel. Bro just use bats.
just run extra conduit in the walls then
Spray Foam expert here, you will be fine. Basically one company now owns all the spray foam in the USA. Huntsman Industries. They bought up everyone. Both open cell and closed cell foam is safe and nothing will catch fire as long as you don't have an open flame near it. Wires are perfectly safe. It is entirely worth it and pays for itself. You spray foam as much shit as you possibly can and if you need a vapor barrier make sure you spray 3" of Closed Cell Foam / 2lb. Open cell is good but will need a vapor barrier. Need any info free feel to ask.
Frick you and your spray foam
Found the homosexual dry waller...go hang some board you monkey...
>You spray foam as much shit as you possibly can and if you need a vapor barrier
If I used closed cell does it count as a vapor barrier?
do I need to put vapor barrier boxes around my electrical boxes if I use closed cell foam?
>It derates all your wires.
source? everyone else is saying the code says it's perfectly fine
> derates wires
It’s obvious that it will. It’s physically impossible not to.
Got a kettle, coffee maker, or toaster oven? Use it once and feel how warm the cord gets at the end. Now use it again after you’ve wrapped the end with foam or other heat insulation. You can melt through the plug in some cases.
Building codes specify the absolute minimum requirements and are not always updated with fads like spray foam.
If you have to, just use rockwool in those areas. At least it’s not plastic— it’s non-flammable rock.
Even better, put it in conduit.
You could also use 12 ga wire and keep the 15A breaker at 15A.
Or all three.
Anyway, when I built my own house, i tended to go beyond the absolute minimum construction standard. The cost as minimal for the best materials. 80% is labor costs by high school dropouts that want to make 6 figure salaries.
This stuff is hazardous
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Even the orange furnace stuff still kinda burns if a flame is touching it.
Haha…I knew spray foam was bad, but I didn’t think it was that bad…. Government must be desperate to keep the population down by approving that. Of course the fumes would have killed everybody way before any actual fire.