When your heater acts up: quick fixes that saved my winter

expanding foam is basically mouse confetti... they love tunneling through that stuff.

Couldn’t agree more - expanding foam is a joke against rodents. Hardware cloth’s the way to go, but I’d argue you need to double up in some spots. Mice are relentless, especially when it gets cold. I’ve seen them squeeze through gaps you’d swear were airtight. Cardboard and duct tape? Been there, done that... but nothing beats a solid metal patch if you want to sleep at night.

Metal patching is the only thing that’s ever held up in my experience. I’ve been called out to crawlspaces where folks tried everything - foam, steel wool, even a bit of chicken wire - and the mice still found a way through. One guy had stuffed every gap with expanding foam thinking it was “rodent proof.” Six months later, there were tunnels like a hamster cage.

I’ll admit, I used to think steel wool could do the trick if you really packed it in, but those little suckers will chew right around it if they’re determined enough. Hardware cloth is solid, but yeah, double it up at corners and anywhere pipes come through. Mice have a sixth sense for weak spots, especially near old heater vents or where someone got lazy with the caulk.

Cardboard and duct tape just make their lives easier. If you want a real fix, sheet metal and screws are the way to go. Might not look pretty, but you’ll actually keep warm without sharing your house with a mouse family.

I get the whole “sheet metal or bust” thing, but honestly, I’ve had decent luck with a combo approach that doesn’t break the bank or require a tetanus shot. Here’s my two cents:

1. Steel wool *plus* caulk. Stuff the steel wool in deep, then seal over it with a thick bead of silicone caulk. The caulk keeps the wool in place and makes it less appealing for mice to mess with. It’s not Fort Knox, but it’s held up for me in a 100-year-old house with more gaps than insulation.

2. For bigger holes, I’ll use hardware cloth (the 1/4” stuff), but instead of sheet metal, I just staple it tight and then slap some duct seal putty around the edges. Not pretty, but it’s cheap and you don’t need power tools.

3. If you’re desperate, peppermint oil on cotton balls actually seemed to slow them down for a while - at least until I could patch things up properly.

Not saying metal isn’t the gold standard, but sometimes you gotta work with what you’ve got in the junk drawer.

Editorial correction — 21 October 2026

Loose denim is not a substantiated rodent barrier. Close entry gaps with appropriately sized, secured exclusion materials and durable edge sealing suitable for the location; do not infer that the existing installation has already failed.

The original post is retained below for context.

Not saying metal isn’t the gold standard, but sometimes you gotta work with what you’ve got in the junk drawer.

Honestly, I’m all for skipping the sheet metal if it means less waste and fewer trips to the hardware store. I’ve done the steel wool + caulk trick too - works fine, and you don’t end up tossing a bunch of sharp scraps. Hardware cloth is decent, but I’d swap duct seal for some eco-friendly clay or even old denim scraps if you’ve got ‘em. Mice hate that stuff, and it’s one less thing in the landfill. Peppermint oil? Yeah, it’s a band-aid, but at least your house smells better than the neighbor’s.

You’re speaking my language - sometimes you just gotta MacGyver it with what’s in arm’s reach. I’ve patched more than a few holes with steel wool and caulk, and honestly, it holds up better than folks give it credit for. Old denim scraps? That’s a new one for me, but I can see how that’d work. Plus, it’s way less itchy than fiberglass.

I hear you on the peppermint oil. It’s like putting a pine tree air freshener on a leaky exhaust - doesn’t fix the problem, but at least it smells festive while you figure out a real solution. Hardware cloth is solid, but man, cutting that stuff up is a pain if you don’t have the right snips.

End of the day, whatever keeps the critters out and the heat in is a win. No shame in getting creative, especially if it means fewer trips to the store and less junk tossed out.

Old denim scraps? That’s a new one for me, but I can see how that’d work. Plus, it’s way less itchy than fiberglass.

- Denim’s smart - never thought of that either.
- Steel wool and caulk combo is classic, but I’ve had mice chew through if I didn’t pack it tight enough.
- Hardware cloth: yeah, cutting it sucks unless you’ve got aviation snips. Regular scissors = instant regret.
- Ever try using expanding foam for gaps? It’s messy but fills weird spots fast. Downside: not great near heat sources.
- Curious if anyone’s tried those spray-on insulation kits - worth it or just hype?

Expanding foam is a double-edged sword for me - used it once to seal up a weird gap behind my water heater, and it did the trick, but man, that stuff sticks to everything. Had to scrape it off my hands for days. I’ve never tried the spray-on insulation kits, though. Are they any better for tight crawl spaces, or just as messy? Also, anyone ever use copper mesh instead of steel wool? I heard it’s better for rodents but haven’t tested it myself.

Expanding foam’s a wild ride, isn’t it? I’ve had it bond to my skin like superglue - learned the hard way to always wear gloves. As for those spray-on insulation kits, they’re just as messy if you’re not careful, maybe even worse in cramped spots since the nozzle can go rogue. On copper mesh: I swapped out steel wool after mice chewed right through it. Copper’s pricier but doesn’t rust or fall apart over time, and rodents seem to hate it more. Worth the investment if you’re patching up problem areas.

Copper mesh really does seem to be the way to go for rodent-proofing. I tried steel wool too, but after a couple of months, I noticed little bits of it rusting and falling out - plus, the mice just pushed it aside. The copper’s held up way better in my basement vents.

On the expanding foam front, I’m still trying to figure out the best way to control the mess. I’ve heard some folks use painter’s tape to mask off the area, but I always end up with more foam than I need. Has anyone found a trick for getting a cleaner application? Or maybe there’s a brand that’s less prone to going wild?

Also, curious if anyone’s had luck with those DIY spray insulation kits in really tight crawlspaces. I’ve been thinking about tackling the space under my stairs, but I’m worried about overspray and breathing in fumes. Did you use any special gear or just power through with a mask and goggles?

Painter’s tape helps a bit, but I’ve found using a damp rag to wipe the nozzle between bursts gives you more control. Short, quick squeezes - never one long spray. As for brands, Great Stuff Pro is a little less wild than the regular cans, in my experience. For crawlspaces, I’d never skip a decent respirator and goggles... those fumes are no joke, and it gets everywhere if you’re not careful. I tried it once under my porch - took longer to clean up than to spray.

I get the appeal of painter’s tape, but honestly, I’ve had better luck just using a cheap plastic drop cloth and letting the foam do its thing. The tape always seems to peel up or get gunked. And about the respirator - yeah, those fumes are rough, but I swear the cleanup is worse if you try to rush it. I once got foam in my beard... took days to get it out.

The tape always seems to peel up or get gunked.

Funny you mention that - I've had the same issue with painter’s tape, especially if the surface isn’t perfectly clean or there's any moisture. Ever tried the blue “delicate surface” tape? I found it sticks a bit better, but still not perfect. As for cleanup, yeah, foam is brutal once it cures. Did you use acetone for your beard incident, or just lots of patience? I’ve never found a magic fix for that...

Did you use acetone for your beard incident, or just lots of patience? I’ve never found a magic fix for that...

Tried acetone once - never again. My beard smelled like a nail salon for days, and it didn’t help much anyway. Ended up just trimming the chunk out. As for tape, I’ve noticed if you press it down with a putty knife, it holds a bit better, but yeah, moisture ruins everything. Foam cleanup is just a lost cause after it sets. Learned that the hard way under a crawlspace...

Yeah, acetone’s a nightmare for facial hair. I tried scrubbing with dish soap once, but honestly, nothing really gets that foam out if it’s cured. Ended up with a weird patchy beard for a couple weeks - my wife still laughs about it. As for tape, I’ve found that blue painter’s tape works better than duct tape in damp spots, but even then, it’s hit or miss. Crawlspaces are just unforgiving.

Yeah, crawlspaces are brutal. I’ve had blue tape peel right off after a day if there’s even a hint of moisture. Honestly, sometimes the only thing that holds is that stretchy self-fusing silicone tape, but it’s kinda pricey and not always on hand. About the foam - tried shaving it out once, just made it worse. Guess some lessons stick... or in this case, don’t come off at all.

Honestly, sometimes the only thing that holds is that stretchy self-fusing silicone tape, but it’s kinda pricey and not always on hand.

I get where you’re coming from, but I’ve actually had better luck with the old-school friction tape in damp crawlspaces. It’s not perfect, but it sticks better than blue tape and doesn’t cost as much as the silicone stuff. Foam’s a pain, though - once it’s in there, you’re pretty much stuck with it. Tried scraping it out once and just ended up making a mess. Sometimes you just gotta patch and move on.

- Friction tape’s definitely a classic, and honestly, it’s saved my butt a few times too.
- For me, I try to avoid anything that’ll end up in the landfill quick - so I usually reach for reusable wraps or fabric-based tape if I can.
- Silicone tape’s cool but yeah, price tag hurts.
- Foam… ugh. Once it’s on, it’s like trying to get gum out of carpet. I just leave it unless it’s actually blocking airflow or something critical.
- Sometimes I wonder if the “quick fix” is just learning what you can actually live with until spring...

Honestly, friction tape’s underrated - old school but it just works. I hear you on the foam; once that stuff sticks, it’s not coming off without a fight. I’ve had to cut it out with a utility knife before. Sometimes, “good enough till spring” is the only real option when you’re knee-deep in winter. But yeah, reusable wraps are smart if you can swing it. Silicone tape’s nice, but I save it for stuff I actually want to fix right the first time… otherwise, gimme the cheap stuff.

I’ve wrestled with that foam insulation too - one winter I tried to “upgrade” my pipe wrap and ended up with a sticky mess that just wouldn’t budge. Ever tried using heat shrink tubing for a quick fix? I’ve had mixed results, but it was cleaner than the foam at least. Friction tape’s solid, but I always wonder about how it holds up long-term with moisture. Any issues there?

Heat shrink tubing’s definitely neater than foam, but it can be tricky if the pipe’s got any bends or odd fittings - sometimes you just can’t get a good seal. Friction tape does alright for a season or two, but in damp basements I’ve seen it start to break down or get gummy over time. If you’re dealing with real moisture, I’d lean toward a proper pipe wrap or even self-sealing silicone tape. It’s not perfect, but it holds up better than most quick fixes I’ve tried. Don’t beat yourself up over the sticky mess - happens to the best of us.