I get the sealing thing, but honestly, I've had my deck for about 8 years now without sealing underneath and haven't had major issues yet. Maybe it's luck or climate...but spiders definitely moved in anyway, sealed or not, lol.
Yeah, you're probably onto something with climate playing a role. I've seen decks in drier areas hold up surprisingly well without sealing underneath, while in wetter climates, moisture buildup can cause rot pretty quickly. Spiders though...they're inevitable, sealed or not. I once pulled up some decking boards on a client's deck that looked perfect from above, but underneath was a whole spider metropolis—webs everywhere. Structurally it was fine, but definitely made me rethink crawling under decks without gloves and goggles.
Still, even if things look good on the surface, it's worth occasionally checking the joists and supports underneath for signs of moisture damage or insect activity. Eight years is pretty solid though—sounds like you've got decent airflow under there at least.
You make a good point about climate and airflow, but honestly, eight years without a thorough check underneath feels a bit long to me. I've seen decks that looked perfectly fine from above but had some serious structural issues lurking below—especially around ledger boards and joist hangers. Moisture can be sneaky, even in drier climates, especially if there's any spot where water pools or drips regularly.
Here's what I'd recommend doing at least every couple of years (or sooner if you've had particularly wet seasons):
1. Grab a flashlight and do a quick visual check underneath. Look closely at the ledger board—the piece that attaches your deck to the house. This is often the first spot to show signs of rot or moisture damage.
2. Check your joist hangers and fasteners. Rust or corrosion can weaken them over time, even if the wood itself looks okay.
3. Give the posts and footings a good look-over too. Sometimes soil erosion or shifting can cause posts to settle unevenly, creating stress points on your deck.
4. While you're down there, gently poke around suspect areas with a screwdriver or awl. Wood might look solid but could be softening internally from moisture or insect activity.
I know spiders aren't exactly fun to deal with (trust me, I've had my share of surprise encounters under decks...), but they're usually harmless compared to carpenter ants or termites. Those guys can do real structural damage before you even realize they're there.
Also, airflow alone doesn't always guarantee safety—I've seen decks with decent ventilation still develop hidden rot spots because of poor drainage or improper flashing installation. It's worth double-checking those areas periodically too.
Not trying to sound overly cautious here, just sharing what I've learned from experience. Better safe than sorry when it comes to something you walk on every day, right?
Yeah, gotta agree with you here. I used to think airflow alone was enough until a few years ago when my deck's ledger board nearly gave out—looked fine up top, but underneath... total mess. Now I'm under there every spring, spiders be damned.
"Now I'm under there every spring, spiders be damned."
Haha, I feel you on the spiders! But seriously, good call checking every spring. I've seen decks that looked pristine from above but were quietly rotting away underneath—it's scary how quickly moisture can do damage without anyone noticing. Usually, I recommend clients do a thorough check at least once a year, especially after winter when moisture and ice have had their way. If you're not sure what to look for, it's worth having a pro inspect it every couple of years just for peace of mind. Better safe than sorry...and better spiders than structural issues any day.
