I'm finishing my basement and am currently working on the insulation. I finished placing the insulation batts in the studs and am at the point where I am filling in any small gaps with spray foam. I am wondering if I am able to use the spray foam (specifically Great Stuff Big Gap Filler) over electrical wires, or if I should avoid them. The picture below is an example of a spot where I used great stuff to fill a gap, but avoided an electrical wire. I am wondering if I can fill this gap, and other gaps with electrical wiring. If I can't use Great Stuff Big Gap Filler, are there other spray foam products that I can use over wires?

An example of a spot where I used great stuff to fill a gap but avoided an electrical wire

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    I'll wait for someone that knows for sure, but I see no reason you could not foam that.
    – RMDman
    Feb 25 at 23:47
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    Are you familiar with the general flammability of that stuff? If fire was not an issue I'd say it's really good stuff. Unfortunately... Feb 26 at 0:44
  • I imagine for tiny spots, while spray foam is easy, stuffing regular insulation in to stop drafts is okay also. The heat loss is not as important as draft stop is.
    – crip659
    Feb 26 at 0:53
  • go outside and make a stripe of the filler. Light it with lighter. Does it just melt or burns
    – Ruskes
    Feb 26 at 0:53
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    I suppose that using the fire foam is (1) compliant, and (2) works perfectly well. On the downsides, there’s two cans of foam in play, and it’s probably totally unnecessary to go to such lengths. (If it was my house, I’d just use the regular foam.) Feb 28 at 3:30

1 Answer 1


The instructions for the insulation I use (which has wiring channels actively suggested using spray foam to fill in where we cut openings for electrical boxes, so they think it's compatible....

  • While I do think it is OK, the question is in contact with cables and your example is, I think around the outside of boxes - a step further from the wires themselves. Feb 26 at 0:59
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    Outside of boxes and the NMC running into them. In fact they suggested that the foam might qualify as the required mechanical fastening for the cable. I grant that this is still outside the sheathing, though.
    – keshlam
    Feb 26 at 2:51
  • Anecdotally, my electrician told me after the heavy up was done & inspected to fill the around the service entrance cable with great stuff foam, which I did. But I don't know in terms of code (he didn't want me to do that before inspection in case the inspector didn't like the way the cable was run, which would have been a big problem) Feb 26 at 3:05

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