What should I use to seal gaps around pipes under my sink?

I've spent years cutting spray foam away from copper supply lines, and I can tell you right now: don't do it. It’s a massive pain for the next person who has to swap out a shut-off valve or fix a pinhole leak. Foam sticks to everthing and can actually trap moisture against the pipe, wich leads to corrosion over time. And duct tape? Forget it. The adhesive will dry out in the heat under the sink, and it’ll just be a sticky mess hanging off the wall in six months. The cleanest way to fix this is with **split escutcheons**. They’re those little chrome or white plastic rings that snap around the pipe. Since your holes are oversized, you can specifically look for "deep" or "box" escutcheons, or even floor plates, which have a much wider diameter than the standard ones. They hide the ugly jagged edges of the drywall perfectly and give it a proffesional look without being permanent. If you’re genuinely worried about mice or spiders, you need somethig they can't chew through. Stuff some **stainless steel wool** into the gap before you snap the escutcheon on. Mice hate the stuff because it cuts their mouths, and unlike regular steel wool, it won't rust and leave red stains on your cabinet. For the draft, you can use a bit of duct seal—it’s a gray, clay-like putty that stays soft forever. You just knead it in your hand and smash it into the gap. It blocks the air but stays flexible, so a plumber can just pull it out with their fingers if they ever need to get back in there. If the hole in the drywall is just ridiculously huge, like a five-inch crater for a two-inch pipe, don't bother with sheetrock mud or tape. Just cut a small square of 1/4-inch plywood or plastic sheeting, drill a hole in the middle, cut it in half, and screw those two pieces to the wall around the pipe. Then put your escutcheon over that. It’s solid, keeps the pests out, and takes about ten minutes to remove if you ever have to work on the drain.

That duct seal stuff sounds way better than foam. I've never heard of it before—is it somethig I can find at a regular hardware store or is it a specialty plumbing thing? Also, if I use the stainless steel wool, do I need to worry about it scratching up the white PVC drain pipe? I don't want to accidentally cause a leak while trying to keep the mice out.

You'll acutally find duct seal in the electrical aisle, not plumbing. Look for a gray brick wrapped in plastic near the conduit fittings; it's ussually labeled as "sealing compound." As for the PVC, don't sweat it. That pipe is tough as nails compared to a bit of steel wool. You won't cause a leak unless you're taking a hacksaw to it.

If the gap is truly massive, check the drainage section for a jumbo 2-inch split ring. Sometimes the standard ones are too wimpy for those hack-job holes builders leave behind. Just snap it on and you're golden.