What it usually means, the likely causes in order, what to safely try first, what a pro charges in Canada, and when to stop and call one.
This guide covers the common cases. Describe your exact problem and get a personalized diagnosis — free to start, with a DIY vs. call-a-pro verdict and a real cost estimate.
A leaning or wobbly deck or fence is a structure whose support has moved. The boards and rails people blame are usually still sound; it is what holds them up that has shifted, most often a post footing that frost has heaved, soil has softened, or decay has weakened. A fence that leans a little more each spring and a deck that has started to sway are telling the same story at different stakes. The diagnostic task is to find which support has moved, whether it is still moving, and whether anything structural has cracked or rotted in the process, before anyone straightens and braces the wrong thing.
This worsens if delayed, because a leaning structure loads its remaining supports unevenly and movement tends to accelerate once it starts. A slightly leaning fence panel is a schedule-soon job; a leaning deck, a deck that sways underfoot, or any structure leaning toward a house, walkway, or a neighbour property deserves prompt attention and light use until it is inspected. If the lean visibly worsens over days, or posts look cracked or crushed, keep people off and away from it until a professional has seen it.
In cold climates, soil moisture freezes and expands, and a footing that is too shallow or bearing on frost-susceptible soil gets lifted or tipped a little each winter. The telling pattern is seasonal: the lean is worse after freeze-thaw cycles and may partly settle back in summer, a little less completely each year.
A post rotting at ground level, a footing that has cracked, or a post simply buried in soil without a proper footing loses its grip and lets the structure drift. Check the base first: if the post itself is soft or the ground around it is disturbed and soft, the footing, not the frame, is the failure.
Water washing soil away from footings, downspouts discharging at a post, or fill soil that was never compacted all let a footing sink or tilt. A lean that follows a slope, a washout channel, or a chronically wet area points to the ground itself giving way beneath an otherwise sound structure.
Sometimes the posts are plumb and sound but the frame above them has lost its stiffness: a rusted-out post base bracket, pulled fasteners, a broken rail connection, or diagonal bracing that was never fitted. The structure racks sideways as a parallelogram rather than tilting from the ground, and pushing it shows movement at the joints.
| Job size | Typical estimate (CAD) |
|---|---|
| Simple fix — the straightforward version of this repair | $150–$350 |
| Major job — complex, hidden, or replacement-level work | $1,000–$8,000 |
Estimates only, calibrated to Greater Toronto Area trade rates and adjusted by region on this site — not a quote. Your exact price depends on the cause, parts, and access. A personalized diagnosis narrows this range using your specific symptom.
A homeowner can reasonably re-plumb a single fence post whose footing has shifted in soft soil, re-set it properly in compacted gravel or concrete, and replace a failed bracket or brace on a sound frame. Decks are a different category: a leaning or swaying deck, any footing replacement under load, and any structure where posts or beams are rotted or cracked belongs to a pro or an experienced builder. A pro will also judge footing depth against local frost conditions, which is the difference between a repair that holds and a lean that returns next spring.
Bracing a structure whose footing has failed treats the symptom and often overloads the remaining good supports. If a post is plumb and sound but a joint has loosened, tightening and bracing is a fair repair. If the post itself has heaved, sunk, or rotted, the footing has to be re-set or replaced, and the bracing goes on afterwards. Pushing against a compromised deck without knowing which support failed can also crack connections that were still holding.
That seasonal rhythm is the fingerprint of frost heave. Moist soil around a shallow footing freezes and expands in winter, lifting or tipping the post slightly, and the spring thaw rarely settles it back to exactly where it started, so the error accumulates year over year. The lasting fix is a footing set below the local frost depth on drained, compacted material, not repeated straightening of the post above ground.
Rarely, but context decides. A fence leaning modestly into your own yard, changing slowly, is a plan-it-soon repair. It becomes urgent if it leans over a sidewalk or a neighbour property, if a panel or post could fall on a path people use, if it is moving noticeably over days, or if it carries a gate that children push through. A leaning deck always ranks higher, because people stand on it and a railing is part of the structure.
Check the posts individually with a level. If individual posts are out of plumb at ground level, the problem starts at the footings or post bases. If every post stands plumb but the whole top frame racks sideways when pushed, the posts are fine and the stiffness has been lost in the joints, rails, or bracing above them. The two problems have entirely different repairs, so this ten-minute check is worth doing before getting quotes.
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