What tool cuts closed cell foam but not Romex?
DCcontrarian
| Posted in Green Building Techniques on
Is there such a thing?
When a house has been spray foamed, the foam hides any wiring or plumbing in the space. I’m starting to see it happen a lot that someone needs to drill a hole in the rim joist and they just drill into the foam and hit whatever’s lying there. And fixing it is a colossal pain because you have to clear out the foam, at the risk of damaging something else.
So best practice is to clear the foam before drilling. But how? The best way I’ve found is to use a hole saw in a T-shaped screwdriver handle to carefully remove the foam by hand. But even that will nick the Romex if it hits it.
Any ideas?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
You can do what the utility crews do when locating underground lines in the final few inches: probe for them. In the utility world, we use a steel rod about 1/4"-5/16" or so in diameter, with a rounded tip, about three feet long. We put a T handle on this. You can now poke the rod into the ground -- it will stop if it hits a pipe, but it won't puncture it. We do this to localize things when we need to know EXACTLY where something is. You can do the same thing in spray foam, just use a smaller rod. I've used a piece of wire coathanger wire for this purpose before. Just round over the "point" on the end to avoid damaging wires.
Another option is a small stiff-blade putty knife. You can press this into the foam too (it doesn't need to be sharpened), and it will stop if it hits something. Probe around the area where you want to cut or drill to verify it's free of embedded wires or pipes. Once you're reasonably confident there is nothing there, it's safe to get out the power tools.
Bill