code-complianceelectricalfoundationjoists
I’m boring some holes to run new wiring and there happened to be two adjacent floor joists under where I was drilling, so I drilled diagonally-vertically through one of the joists. The hole is 3/4” thick. Is this hole a code violation? Did I just compromise the integrity of my foundation?
Pictures below of the hole in question:
Disclaimer: We bring in outside contractors for our electrical installs, so I can give you some general tips, but I'll defer to others that may know more about this specific problem.
In general, joists, and any lumber supporting a load on its side, will lose much of its carrying capacity when it is drilled or cut on the top or bottom. For passing through the joists, you should make the hole in the center (between the top and bottom) of the joist, and make it the smallest hole that allows the wire to pass freely.
Having a double joist running beneath a wall means that the wall and joists are designed to be load bearing. So because of this, unless someone with more structural knowledge says it's ok to drill a hole, I'd avoid it.
While I can't think of a good way to get the wire into the wall, you could install your outlet on an adjacent wall, or you could go for a floor mounted outlet as a last resort:
Replacing them? Getting an engineer? For a 1/2 hole in at least 8in joist? Seriously? I mean I'm sure the joist has lost some percentage of its strength. Like pretty small percentage. I would speculate that the lost strength is within tolerance limits for wood, which is not uniformly perfect. Unless you plan on having sumo wrestlers fight on top of those joists, I would just let them be....
Best Answer
I called a local engineer and he said that it was sufficient to fill the hole with epoxy putty. I mentioned screwing in some straps around the hole and he said that’s great but not necessary in this case.