Should an electrician leave a hole in the stucco after conduit installation?

Leaving an open gap like that isn't just lazy; it's technically a code violation in most jurisdictions because all exterior penetrations have to be sealed against moisture and air. Most electricians will at least slap some gray **duct seal** putty around the pipe. It’s that play-dough looking stuff that stays flexible and blocks out the critters. If he didn't even do that, he definately missed a step and left the job unfinished. You are right to be worried about rodents. A mouse can squeeze trough a hole the size of a dime, and a 1/2 inch gap around a conduit is basically a front door for them. Plus, stucco is notorious for trapping moisture. If rain gets behind that wall system, it’s going to rot your sheathing or cause mold issues inside the wall cavity long before you see it on the drywall. It's a localized problem that can turn into a huge headache if ignored.

Now, you could call him back to fix it, but honestly, many electricians aren't exactly artists with finish work. If he comes back, he’s probably just going to squirt some messy silicone in there and call it a day. It’ll be functional but it might look like crap. Since it's a stucco finish, you're actualy better off handling this one yourself if you want it to look invisible. Pick up a small tub of pre-mixed **stucco patch** from a hardware store for about fifteen bucks. If the hole is really deep, stuff a little bit of backer rod or even a piece of scrap insulation in there first to give the patch something to sit on. Pack the stucco patch in, smooth it out with a damp sponge to match the texture, and then paint it once it dries. It takes ten minutes and you'll know for sure that no mice are moving into your master bathroom.

That duct seal sounds like a good temporary fix, but does it eventually dry out and fall off? My neighbor used some of that expanding spray foam on a pipe and it looked gross and turned orange after a summer in the sun.

I’m also curious if putting stucco patch directly against the metal conduit is okay. I read somewhere that some cements can corrode metal over time. shoud I put a layer of tape or somethig around the pipe first to keep it safe from the patch material?

You're right to worry about the corrosion. Standard stucco or mortar has high alkalinity that can eat away at the galvanized coating on EMT over time if it gets wet. Plus, metal conduit expands and contracts differently than your wall does. If you use a rigid patch like stucco, it’ll just crack and leave a hairline gap within a year anyway. I ussually skip the duct seal for finish work becuase it gets grimy. Go grab a tube of Vulkem 116 or a similar high-grade polyurethane sealant in a color that matches your stucco. It stays flexible forever, bonds to the metal and the masonry, and it’s basicly bulletproof against weather. Just mask off the pipe with some blue tape first if you want a clean bead.

Honestly, just grab a tube of polyurethane sealant like NP1 or Vulkem. It sticks to stucco and metal like crazy and stays flexible forever, so the expansion won't crack it like stucco patch whould. It’s way better than standard silicone becasue you can actually paint it to match your house once it cures.

If the hole is too big to just fill, use a bit of backer rod first so the caulk doesn't just fall into the wall. Don't use that spray foam stuff; it's a mess and like someone said, it looks like a science experiment gone wrong after a few months. Just make sure the surface is clean before you apply it.

Check out split-ring escutcheon plates if you want a cleaner look. You can slide one over the pipe after you seal it to hide the gap entirely. It makes the penetration look finished rather than like a mistake. Also, double-check the pitch of the hole. If the electrician drilled with a slight tilt toward the inside, water can follow the conduit right past your sealant and into the framing. I always make sure the hole slopes slightly downward toward the exterior so gravity keeps the moisture out.