Why are my new fence posts leaning?

New fence posts lean for a small number of reasons, and most of them come down to the footing: holes that are too shallow or too narrow, concrete that had not set when the braces came off, backfill that was never tamped, or soil that is loose, wet or heaving with frost. A solid privacy fence also catches the wind like a sail, and a gate pulls on its post every time it swings. A post that leans within the first year can usually be dug out and reset.

The common causes

The holes are too shallow. A short footing is a frequent cause. QUIKRETE's project sheet sizes a post hole at about three times the post's diameter and one-third of the post's overall length deep, plus 6 inches for a gravel base.^[1] Its web guide uses one-third to one-half of the above-ground length, plus 6 inches.^[2] A 6-foot fence on posts with only 18 inches in the ground has very little to resist a strong gust.

The concrete was disturbed before it set. QUIKRETE's fast-setting mix sets in 20 to 40 minutes and can take a heavy load after 4 hours,^[1] but if the temperature is below 72 degrees, it needs more curing time.^[1] Pulling braces early, or nailing rails and boards to posts the same afternoon on a cold day, can shift posts that are not yet firm.

The post was never truly plumb. QUIKRETE's directions brace each post on two adjacent sides and check plumb on both,^[2] and they say to recheck plumb after the dry mix goes in.^[1] A post checked on one face only can look straight from the street and lean along the line.

The backfill and soil. QUIKRETE's sheet says to tamp the sides and bottom of the hole until firm before the gravel goes in.^[1] Loose soil around a footing lets the whole concrete collar tip. For posts in loose or sandy soil, it calls for a larger, dish-shaped hole,^[1] and its web guide recommends a tube form.^[2] Heavy clay that stays wet, common across much of Virginia, softens around a footing after long rains. Downspouts and sprinklers that soak one spot make it worse.

Frost heave. When wet soil freezes, it expands and can lift a shallow footing, often unevenly, so the post tips as it rises. Local design frost depths give a sense of how deep the freeze can reach: Loudoun County lists a frost depth of 24 inches,^[4] Shenandoah County gives 24 inches from grade to the bottom of a footing,^[5] and Powhatan County lists 18 inches.^[6] Those figures are for building footings; fences are not required to meet them, but a short footing in wet clay in a 24-inch county is at real risk. Posts that were straight in September and lean in March point to this.

Wind and weight. A solid board fence takes far more wind than a picket or rail fence. Long spans between posts make it worse: Board fences typically have posts every 8 feet,^[3] and stretching that distance puts more load on each post. Virginia Cooperative Extension notes that post strength is especially important for corner and gate posts.^[3] If one gate post leans and the rest stand straight, the gate is the cause.

The wrong post. It is rare in a new fence, but a post that was not rated for ground contact can soften quickly at the ground line. Untreated sapwood of essentially all species has low resistance to decay,^[7] and the Forest Products Laboratory says pressure-treated wood is recommended for the high hazard of ground contact.^[7] Probe the post at grade with a screwdriver; soft, punky wood means replacement.

Reading the pattern

• One post leans: look at that footing. A soft spot, a buried rock that forced a shallow hole, or a downspout nearby.
• Every post leans the same way: wind on a solid fence, or posts that were all set too shallow.
• Corners and ends lean inward: the rails are pulling on posts that were not set heavy enough.
• Gate post leans toward the gate: the gate's weight. The latch side drops and the gate starts to drag.
• Posts lean in different directions after winter: frost heave or saturated soil.

Fixing it

A post that only leans slightly in soft soil beside a sound footing can sometimes be pushed back, tamped and braced. A post that rocks inside its concrete, or one whose footing turns out to be too shallow, needs to come out and be reset with a deeper, wider hole, gravel and new concrete. Digging around a post is excavation, and Virginia law requires a locate request to the notification center before any excavation,^[8] so submit a Virginia 811 request first; the service is free.^[9] How to set a fence post in concrete walks through resetting it, and QUIKRETE suggests a 6-inch gravel base and a concrete top that slopes away from the post to protect it from rot.^[2]

If many posts are leaning, a full run was likely set short and it is usually better to reset the run than chase single posts. On a new fence, ask the installer first.

Stop and call a pro if

• Several posts or a whole run are leaning, or the fence is tilting toward a neighbour's yard, a driveway or a sidewalk.
• A post sits near utility marks, a buried line or an irrigation pipe.
• The fence is on a slope, on top of a retaining wall, or is a pool barrier.
• A heavy drive gate is sagging and pulling its post over.

If you hire it out, Virginia treats Class C contractors as those performing work where a single contract is over $1,000 but less than $30,000,^[10] so check the business on DPOR's licence lookup. Read whether you need a permit for a fence and what a fence costs in Virginia, browse fence repair and installation businesses, all exterior answers, or exterior businesses around Blacksburg. To get it fixed, describe the leaning fence once and local businesses send written quotes.