When is a deck actually worth repairing vs just rebuilding?

We bought a house with a deck about the same age a few years back, and I went through the exact same mental loop. Two bids said rebuild, so I hired a solo carpenter off a local Facebook group to come look at it for like a hundred bucks. He poked around with an awl, pulled a couple boards, and found the joists over the beam were mush where water had been sitting against the ledger. His take was that once the frame goes, patching is just renting the problem for a year or two.

Here's the thing though, his quote to rebuild was about half of what the two big companies wanted. Same scope, pressure treated frame, similar design. The big outfits had a sales guy, a crew, insurance, overhead, whatever. The small guy just did good work over two weeks. So I'd say your instinct about a third opinion is right, but not because the rebuild diagnosis is wrong. Fifteen or twenty years on untreated framing, expecially if the footings were shallow or the posts sit in water, is honestly when you'd expect rot. Ask whoever comes out to show you the damage. Pull back a board, poke the post at grade with a screwdriver. If it sinks in like butter, that's your answer.

What you're shopping for isn't repair versus rebuild, it's a fair price for the rebuild.

I'm going to push back a bit on the 'get a handyman to patch it' route, because I tried that and it cost me twice. My deck was around 18 years old, a few soft boards, and a handyman swapped out six boards and re-screwed the railing for a few hundred bucks. Looked fine for one summer. Next spring the rail post wobbled and when we finally opened it up, the joists underneath were punky all through the middle of the frame. Ended up paying for the patch AND the teardown, which was more than if I'd just rebuilt the first time. What sold me on the rebuild contractors being honest was checking the posts myself. I dug down a few inches at the base of a couple of them and the wood at grade was soft enugh to press a screwdriver into. That's where old decks die, right at the ground line, and you can't see it from the top. Fifteen to twenty years is also right around when the original fasteners and hangers start letting go, especially if the builder went light on hardware. So if two seperate outfits looked at it and said the same thing without talking to each other, that's usally a real read, not an upsell. A third opinion won't hurt, but I'd weight it toward the structural side, not the cheapest patch quote.

One thing to look at while you're getting quotes: ask to see the bottom of the posts. When I tore mine down after 22 years, every 6x6 had been buried straight into the concrete with no standoff base, and the bottom foot of each one was damp and punky even though the tops looked fine. From the deck surface everything seemed solid, so I get why the diagnosis felt fishy to you. Any legit rebuild bid should include post bases that keep the wood an inch or so off the concrete, so that's a decent test of wheather the contractor knows what they're doing. Also ask if they're pulling a permit, since an elevated deck usually needs one.

Agree with the guy who said check the post bases, that's exactly where mine was hiding rot. My deck was about 20 years old and the walking surface looked decent, but the stringers on the stairs were toast where they sat on the old patio slab. Rain running off the steps just sat there for years. That'd line up with the soft spots you're feeling near your stairs. Also worth asking each bidder if they're pulling a permit, the answers told me a lot about who actually knew code.

Reading this while sitting on my own sketchy deck, so I'm filing all this advice away. One thing I haven't seen talked about is doing the teardown part yourself. A buddy of mine knocked his old one apart over a weekend with a sledgehammer and a pickup truck, saved a chunk of change, and the builder he hired only charged for the new build. Seems like the messiest job is maybe the easiest to cut cost on? Or is there more to taking one of these things apart than just whacking it untill it falls down?

Update: took the tip about checking the bottoms of the posts and dug back the dirt around two of them. Sure enough, the wood down there is soft and dark, definitly been sitting in wet concrete for years. So the rebuild guys weren't just chasing a big paycheck, at least partly. Still not sure about the stair stringers though. If the posts are that bad, does the whole frame usually go with them, or can sound sections be saved?