I've spent years maintaining structures in the wet climates of Western PA near Seven Springs, and the biggest thing I've learned is that the old-school CCA-treated lumber relly was built diferent. If you’re lucky enough to have an older deck still standing after thirty years, you’ve got to be careful about how you clean it. Most people blast the wood too hard with a pressure washer and end up shredding the fibers, wich is basicly a death sentence once that protective layer is gone. Keeping the area under the framing clear is just as important as what you do on top. I see alot of folks let dirt and rocks pile up right against the posts, which traps moisture and invites rot. If you're building near a stream or a damp hollow, make sure you have solid drainage away from those concrete footings. Just because the lumber was rated for ground contact doesn't mean it should sit in a mud pit. A little airflow goes a long way for the beams. If you keep debris away from the base, you'll avoid the structural failures that ussually kill these old builds.
Tips for making pressure-treated decks last decades that nobody talks about
Jul 24, 2026
Last reply: 15 hours ago
3 Replies
I've got a porch out in the Laurel Highlands that’s hitting its 25th year, and I've noticed the same thing about that old CCA green wood. When I tried to refresh the surface last summer, I skipped the pressure washer entirely and just used a stiff brush with some diluted 30 Seconds Outdoor Cleaner. Even at a low PSI, I was worried about fuzzing the grain like you mentioned.
Regarding the airflow, I actually had to dig out about four inches of river rock and silt that had settled against my 6x6 posts over the decades. I ended up backfilling with some larger 2B gravel to help the water move away from the footings. It made a huge difference in how fast the area dries out after a heavy rain. I also threw a coat of TWP 100 series on the top boards, and it seems to be soaking in better than the film-forming stuff I used back in the late 90s.
Hardware's usally what kills these before the wood even flinches. I've crawled under plenty of 90s builds where the CCA's still perfect but the lag bolts are rusted down to toothpicks.
If you haven't checked lately, take a look at those ledger connections. That old treatment's real aggressive on fasteners if they aren't heavy-duty galvanized. It's crazy how the timber outlasts the metal almost every time.
This is absolutely wild that a deck can last that long! I just moved into a place with a small platform deck and I'm hoping it holds up half as well. Since you guys are experts on these older builds, do you think heavy planters or those big outdoor rugs cause more rot problems than they’re worth? I realy want to spruce up the look with some greenery but I'm terrified of trapping moisture on the surface now!
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