How can I fix a sagging support post on my two-story deck?

That sagging is usually a sign that your main beam isn't actually a beam, but just a couple of rim joists nailed into the side of a post. If the house was built in the 70s, it’s common to find decks where the entire weight of the structure is held up by the shear strength of a few rusty nails or bolts. That is incredibly dangerous for a double-decker setup, expecially with a roof involved. You’re looking at a potential total collapse if those fasteners finally give out. First thing you need to do is check the bottom of that post. If it’s buried directly in the ground, it’s almost certainly rotting out or sinking because there’s no proper concrete footer underneath it. To fix this, you have to build a **temporary shoring wall** about two or three feet back from the sagging beam. Use a double 2x10 top plate supported by adjustable screw jacks or temporary 4x4 posts on solid ground. You need to transfer that roof and floor load off the failing post before you do anything else.

Once the weight is secured, you can slowly jack the structure back to level. Do it gradually—maybe a quarter-inch a day—so you don't stress the house connection or the porch framing too fast. You’ll likely need to dig out and pour a new **concrete pier** with a proper footer that goes below the frost line. Don't just dump a bag of Quikrete in a hole; do it right with a sonotube and a post base. When you reinstall the support, the beam must sit directly **on top** of the post. Never bolt it to the side. If your current beam is undersized or just made of individual joists, sister in some new pressure-treated lumber or an LVL rated for exterior use. Use galvanized structural connectors to tie everything togather. It's alot of work, but with a heavy snow load coming, you can't afford to let that post keep sinking.

I’m dealing with a similar dip on my porch and the idea of jacking up a roofed structure is honestly pretty scary. If I use those screw jacks for the shoring wall, how do I make sure the ground under them won't just give way while I'm trying to lift? My yard gets relly soft when it rains.

Also, for the beam-to-post connection, are there specific brackets that are easier for a beginner to use? I'm worried about the whole thing shifting out of alignment once I cut the old posts away.

To keep those jacks from sinking into the mud, you've gotta use 'mud sills.' Just grab some 2x12 pressure-treated scraps and double them up under the base of each jack to spread the load. If it’s still sinking, you might need to wait for a dry week before you start jacking. As for brackets, look at the Simpson Strong-Tie BC or AC series. They’re basially foolproof for connecting a post to a beam. Just make sure you’re using the proper galvanized structural screws—don't use standard deck screws or they'll just snap under the shear pressure once the snow hits.

One thing people overlook is the ledger board at the house. If that middle post has been sagging for years, it’s probably been pulling on the lag bolts or nails holding the deck to your siding. While you've got it jacked up, definitly crawl under there and make sure the ledger isn't pulling away or splitting. If it looks loose, now is the time to add some tension ties or new structural screws. You don't want to fix the post just to have the whole thing pull off the house later because the connection was stressed.