Most St. Louis deck damage traces back to the same cause: the ground and the fasteners moved, not the wood rotting from neglect. Winters here freeze and thaw over and over instead of settling into one long cold stretch, and that back-and-forth is what backs screws out of joists, cracks the seal at a ledger board, and slowly heaves a footing that was never poured deep enough to begin with. St. Louis Deck Pros connects you with a local contractor who knows the difference between a deck that needs a few fasteners replaced and one where the frost has actually beaten the frame. Call (314) 626-3663 and describe what you're seeing.
Water gets into small gaps, freezes, expands by about nine percent, and pries whatever it's inside a little further open than it was. Do that dozens of times over a winter, not once, and the damage compounds instead of healing between cycles. In a deck, that shows up in three places more than anywhere else: at fastener holes, where repeated freezing works a screw's threads loose in the surrounding wood fiber; at the ledger connection, where trapped moisture behind the board freezes against the house and slowly pries the flashing or caulk seal apart; and underground, where soil that's saturated with water expands as it freezes and can lift a footing that isn't set below the frost line. None of this happens in one dramatic event. It happens in small increments every time the temperature crosses 32 degrees, which in a St. Louis winter can happen more times in a season than most homeowners would guess.
A footing poured too shallow, or poured before local code required a minimum depth, sits in the layer of soil that actually freezes and thaws each winter. As that soil freezes, it expands and pushes upward on anything sitting in it, footing included, and as it thaws the footing doesn't always settle back to exactly where it started. Repeat that for enough winters and a footing can rise or shift out of level, which shows up above ground as a post that's no longer plumb, a deck surface that's developed a slope it didn't used to have, or stairs that no longer line up cleanly with the ground. Footings set well below the frost line and on undisturbed or properly compacted soil mostly avoid this. Footings that were poured fast on a builder-grade original deck, especially anything older than fifteen or twenty years, are the ones a repair visit usually finds moving.
Two things stack on top of each other. The freeze-thaw cycling described above works any fastener loose over time, screws and nails both, simply through repeated small movement in the wood around them. On top of that, most pressure-treated lumber sold since the mid-2000s uses a copper-based preservative called ACQ that corrodes plain steel and even standard galvanized fasteners far faster than older treatment chemicals did. A deck built with the wrong fastener type, coated screws that aren't rated for ACQ contact, for instance, can show corrosion and fastener failure years before the boards themselves are anywhere near replacement. The fix during a repair is straightforward: hot-dip galvanized or stainless fasteners rated for modern treated lumber, installed at the spacing the decking manufacturer actually specifies instead of whatever was on hand.
Seeing popped screws, a leaning post, or a step that's pulled away from level? Call (314) 626-3663 for a free inspection before the damage spreads further.
Any one of these on its own might be minor. Two or three together, especially a leaning post paired with a sloped surface, usually means the movement is coming from below and not just from worn boards.
It depends on whether the damage stayed on the surface or reached the structure. Fastener replacement, board swaps, and re-sealing a ledger connection are repairs, and they're usually finished in a day by a crew that knows what they're looking at. A footing that's actually heaved out of level, a ledger that's separated far enough from the house to compromise the connection, or joists that have rotted from years of trapped moisture are structural problems, and patching around them without fixing the underlying cause just delays the same repair call a year or two down the road. A contractor who checks the ledger, footings, and joists first, before ever talking about which boards look bad, is the one giving you an honest answer instead of a quick sale.
If you're seeing a leaning post, a visibly separated ledger, or boards that feel spongy underfoot, treat it as unsafe until someone looks at it, particularly for weight-bearing areas like stairs. Cosmetic wear, faded finish, or a single loose baluster is usually not an immediate safety issue, but it's still worth having checked before it becomes one. When in doubt, limit use and call for an inspection rather than guessing.
It depends entirely on what's actually wrong. Board and fastener replacement on an otherwise sound frame is the least expensive category of repair. Ledger reattachment or footing correction costs more because it involves structural work, sometimes requiring the deck to be partially supported or lifted while the repair happens. A written estimate after an on-site look is the only way to get a real number, since repair cost varies more by cause than by deck size.
Most structural repairs, fastener replacement, ledger work, footing correction, can happen year-round as long as the ground isn't frozen solid at the exact repair location. Staining and sealing are the parts that really do need to wait for warmer, drier weather, since finish won't cure properly in cold or damp conditions. If you're seeing a safety issue in the middle of winter, don't wait for spring to call.
Typically not. Insurers generally treat freeze-thaw movement, like frost heave and gradual fastener failure, as a maintenance issue rather than a sudden covered loss, similar to how they treat normal wear from age. Coverage is more likely if a specific event, like a fallen limb, caused the damage instead of ordinary weather cycling. Check your specific policy language before assuming either way.
Once a year is reasonable for most decks, ideally in early spring after the winter's freeze-thaw cycles are done and before the first cookout of the season. A quick check of the ledger, a look underneath at the footings and joists if you can access them, and a walk of the surface for soft spots catches most problems while they're still a repair instead of a rebuild.
Call (314) 626-3663 for a free deck inspection. A St. Louis-based crew will tell you honestly whether you're looking at a repair or something bigger.