Direct answer: A deck footing usually heaves because frost is lifting a shallow footing, water is collecting around it, or the post-to-footing connection has shifted enough to make the deck look like the footing moved. Start by checking whether only one corner rose, whether the beam or post is out of plumb, and whether the soil stays wet around that spot.
Most likely: The most common cause is a footing that is too shallow for the site conditions, with poor drainage making freeze-thaw movement worse.
When a deck footing heaves, the deck may tilt, a railing may go out of level, or one post may look like it got taller over winter. Sometimes the footing itself lifted. Other times the post base loosened, the soil washed out, or nearby framing damage is making the support line move. Reality check: a footing that rises and drops with the seasons is still a footing problem, not normal deck behavior. Common wrong move: packing dirt back around a lifted footing and calling it fixed.
Don’t start with: Do not start by shimming the beam, cutting the post shorter, or pouring a little concrete around the exposed footing. Those moves hide the problem and can make the support less stable.
A single post or support line looks taller, nearby boards slope, and the change showed up after cold weather or a wet season.
Start here: Start by checking that footing area for standing water, exposed concrete, and a post that is no longer straight.
You can see more of the concrete pier or footing than before, or the soil has pulled away around it.
Start here: Start by checking whether the soil is washed out or if the whole footing lifted with frozen ground.
Railings lean, doors may rub near the deck, or one beam line looks high even though the footing is partly hidden.
Start here: Start by sighting the post and beam for movement, then look for a loose post base or framing damage above the footing.
The deck rises in winter or spring and settles somewhat later, but never quite returns to the same position.
Start here: Start by treating it as frost heave and drainage trouble until you prove otherwise.
If the movement showed up after freezing weather and the footing rose mostly upward, frost is the lead suspect. This is especially common when only one or two supports are affected.
Quick check: Look for a footing that sits high compared with the others, with no major cracking in the post or beam.
Water around the footing makes frost heave worse and can also soften soil enough for the support to shift. Downspouts, splashback, and low spots often feed this.
Quick check: Check for soggy soil, erosion channels, mulch piled against the pier, or a downspout discharging nearby.
Sometimes the concrete stayed put but the post base fasteners loosened, rusted, or pulled, making the post lean or ride up slightly.
Quick check: Look at the metal connector where the deck post meets the footing. Gaps, bent metal, missing anchors, or rust streaks point here first.
A cracked beam, rotted post bottom, or failing connection can make the deck look like the footing heaved when the real problem is in the support stack above it.
Quick check: Probe the bottom of the post for softness, and look for beam cracks, split notches, or hardware pulling away.
You need to separate a true footing heave from a loose post base or damaged framing before you try to correct anything.
Next move: If you can clearly isolate one lifted footing or one shifted post connection, move to the ground and drainage checks next. If several supports moved, the whole deck is racked, or you cannot tell whether the footing or framing moved first, treat it as a larger structural issue.
What to conclude: A single high point usually points to one footing area. Widespread movement points to drainage, settlement, or broader structural trouble.
Wet soil and freeze-thaw are the most common reasons a deck footing rises.
Next move: If the area stays wet or clearly collects runoff, drainage is part of the fix even if the footing depth is also wrong. If the soil is dry and stable but the support is still out of position, focus harder on the post base and framing above.
What to conclude: A wet footing area strongly supports frost heave or soil movement. Dry conditions with shifted hardware lean more toward a connection problem.
A lifted-looking deck support is often a failed connection or rotted post bottom, not just a footing issue.
Next move: If the footing is solid but the base is bent, loose, or rusted, a deck post base repair may solve the localized movement once the support is safely stabilized. If the post base looks sound and the post is solid, the footing itself is more likely too shallow or moving in bad soil.
Minor seasonal movement and unsafe support failure are not the same thing, and the repair scope changes fast once bearing is lost.
Next move: If the support stack is still intact and movement is slight, you can focus on drainage control and scheduling a proper footing correction before the next freeze cycle. If bearing is compromised or the framing is stressed, skip cosmetic fixes and move straight to professional structural repair.
Once you know whether the problem is drainage, a failed post base, or the footing itself, the next action should be direct and safe.
A good result: The deck support line should return to solid bearing, stay plumb, and stop moving through the next wet or cold cycle.
If not: If the support keeps shifting after drainage fixes or connector repair, the footing depth, soil conditions, or overall deck support design needs professional correction.
What to conclude: A bad connector can be a localized repair. A heaving footing usually means excavation and reconstruction, not a surface patch.
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Sometimes it drops somewhat as the ground thaws, but that does not mean the problem is solved. If a footing heaved once, the depth, drainage, or soil conditions are still suspect and the support should be checked.
It can be. A small seasonal lift with full bearing is different from a post that is leaning, hanging on hardware, or stressing the beam. Once bearing is compromised, stop using that area until it is repaired.
Gravel can help surface drainage, but it will not correct a footing that is too shallow or already moving in frost-prone soil. It is a support problem first, not just a landscaping problem.
No. If the footing rises and you cut the post, the deck may drop too low when the footing settles, and you still have not fixed the cause. Correct the support problem instead of trimming around it.
If the concrete itself is higher than nearby footings or the soil has separated around it, the footing likely moved. If the concrete looks stable but the connector is bent, loose, rusted, or the post is off center, the post base is a stronger suspect.
Call when the deck is out of bearing, multiple supports moved, the beam or post is damaged, or the fix will require jacking, excavation, and rebuilding the footing. That is usually the right move for anything beyond a simple confirmed connector replacement.