I’ve had decent luck just using exterior-grade paint on plywood edges, but I do run a bead of clear caulk along the bottom where moisture might sneak in. Full-on marine sealant always felt like o...
I get what you mean about marine sealant being overkill—unless you’re basically building a boat, it’s probably more than you need. I’ve had mixed results with just exterior paint though. Ever notice any swelling at the plywood edges after a few storms? I’ve always wondered if a second coat or even a primer underneath might help with that, or if it’s just inevitable with plywood in damp spots. And using old blankets is genius—makes me think of all the drop cloths I’ve ruined over the years. Do you find they slide around much when you’re working?
Yeah, I’ve definitely seen a bit of edge swelling on plywood, especially on the old stuff in my basement stairwell. Even with two coats of exterior paint, the edges seem to soak up any stray moisture like a sponge. I started using an oil-based primer on the cut edges before painting, and that’s helped a bit—though honestly, with our humidity, I’m not sure anything short of epoxy would make it bulletproof.
About the blankets—funny you mention sliding. Mine never seem to stay put unless there’s a ton of junk weighing them down. I tried using those grippy rug pads underneath once, but then it just turned into a tripping hazard. At this point, I just accept I’ll be rearranging them every half hour.
If you ever figure out a magic solution for plywood edges in damp spots, I’d love to hear it. Seems like it’s one of those things you just have to keep touching up over the years.
“Even with two coats of exterior paint, the edges seem to soak up any stray moisture like a sponge.”
That’s the story of every old basement stairwell, right? I swear, plywood edges are like magnets for humidity. I’ve tried the oil-based primer trick too, and it does help a bit, but you’re spot on—nothing short of sealing them in resin seems to last more than a season or two. I actually experimented with wood hardener once (the stuff meant for rotted window sills), and it worked okay for a while, but eventually the swelling crept back in. Maybe we just need to accept that plywood’s got a mind of its own.
The blanket situation made me laugh. I’ve got one of those “weighted” throws that’s supposed to stay put, but somehow it still ends up halfway across the room by morning. Tried the rug pad thing too—nearly wiped out on it during a midnight snack run. At this point, I’m convinced blankets are just naturally rebellious.
Congrats on getting your storm shelter passed, by the way. That’s huge peace of mind. I’m still working up the nerve to tackle mine—last time I checked, there was a family of spiders who seemed pretty invested in their real estate.
If you ever do stumble on that magic plywood solution, let us know. Until then, I’ll be over here sanding and repainting like it’s a new hobby...
- Gotta push back a bit on the “nothing works” front—have you tried marine-grade plywood? It’s pricier, but those edges are way less thirsty.
- I know, it’s not always practical to rip out what’s there, but if you’re ever replacing, it’s worth a look.
- For existing stairs, I’ve had weirdly good luck with a combo of shellac-based primer and a bead of exterior caulk along the edge. Not pretty, but it buys you a couple extra seasons before the swelling circus starts up again.
- And about those blankets—honestly, I think they’re in cahoots with the socks. Never where you left them, always plotting their escape...
Marine-grade plywood’s definitely a step up from standard stuff, but I still can’t get over the price tag unless it’s a spot that’s really gonna take a beating. For most folks, that cost just doesn’t make sense, especially if you’re working with existing stairs or platforms. I’ve actually leaned into using hardwood for replacement treads—not quite as moisture-hardy as marine ply, but with a solid oil-based primer and regular touch-ups, they hold up pretty well in all but the worst basements.
The shellac primer trick is a classic—messy, but it’s saved me more than once when someone called about “mysteriously growing stairs.” Still, I’d argue the real game-changer is making sure you’ve got airflow down there. Even the fanciest materials will swell up if everything’s muggy 24/7. And don’t even get me started on those runaway blankets... I swear they migrate just to mess with us during inspections.
