Driveway Gate Posts and Clearance: Wall Thickness, Footing Depth, Spacing and the Gaps That Make a Gate Work

A driveway gate is a lever hanging on a post. Everything that goes wrong after installation - the latch that no longer meets, the panel that drags one corner, the gate that drifts open on its own - traces back to the post, the footing under it, or a clearance that was never planned. This guide covers the four things to get right before anything is delivered: the posts themselves, the holes they sit in, the spacing between them, and the gaps around the gate.

The hinge post does the work

On a swing gate the hinge post carries the entire panel through the hinges, and the panel's weight acts as a lever that tries to bend the post toward the latch and pull the top hinge out. The latch post only has to hold a latch. So put the strength - wall thickness, footing depth, the best soil - into the hinge post; on a dual swing gate, both posts are hinge posts.

Two wall thicknesses are common, and both are options on our gates:

"Wall" is the thickness of the steel tube, not its outside size; it is what resists bending. If you are between the two, buy the heavier - the difference in cost is small next to resetting a post. Aluminum posts are a poor match for steel gates for the same reason.

For a slider the load is different: rollers carry the weight along a track, the posts guide rather than carry, and the operator pad and the end posts are what need footing.

Footings

Rules of thumb that hold for most residential soils:

• Depth: 36 inches minimum for a typical swing gate, 42–48 inches for panels over 12 feet, heavy infill or an automated gate. Always below the local frost line if that is deeper.
• Hole: 10–12 inches in diameter, belled slightly at the bottom so the concrete plug cannot be levered up.
• Drainage: 4–6 inches of gravel under the post, and slope the top of the concrete away from the post so water sheds rather than sitting at the steel.
• Cure: 24–48 hours before the post takes a gate.

Sandy or wet soil wants deeper and wider; rock wants a core drill and epoxy or a surface-mounted plate on a proper footing. The DIY installation guide walks through digging, bracing and pouring step by step.

Post spacing: the gate is smaller than the opening

A gate is built narrower than the opening so the hinges have room on one side and the latch - or the second panel - has a gap on the other. The instructions that ship with the gate give the exact post-to-post dimension for the gate you ordered; set the posts to that number and the gate fits.

Setting posts before the gate arrives is fine and saves a week, but set them to the number in the instructions, not to a guess. Then measure post to post at the top and bottom and adjust the bracing until they agree. The measuring guide covers what to measure if you are ordering to fit existing posts instead.

The three clearances

Hinge side. The gap between the hinge post and the panel is set by the hinge itself, and it has to let the panel swing without the back corner of the panel striking the post. Weld-on and bolt-on hinges differ; follow the gate's hinge instructions rather than a generic number.

Latch side. Around three-quarters of an inch to an inch between panel and latch post on a single gate, or between the two panels on a dual, is typical - enough to keep the latch meeting through seasons of ground movement, small enough to keep a hand out.

Ground. Two to four inches above the highest point the panel passes over is the usual target on a flat driveway: it clears leaves and small heave, keeps pets in, and looks right. Measure the ground across the whole arc, not at one spot - a crowned driveway is higher in the middle than at the posts. If clearing the high point leaves a large gap at the low point, the driveway has a slope problem that a clearance cannot fix; the sloped driveway guide has the answers (usually a slider or a cantilever).

The swing arc

Each panel needs a clear quarter-circle with a radius equal to its width, on the side it opens toward: no parked car, no garage door path, no planter, no ground that rises into the arc. Two panels halve the radius, which is often why a dual swing fits where a single does not. For a slider, the equivalent is the run-off - a straight stretch of fence line at least as long as the gate.

Plan the arc on paper before the posts go in, because the hinge post's position sets where the arc lands.

Reusing existing posts

Existing posts can be a gift or a trap. Keep them if all four are true:

1. Plumb in both directions, and post-to-post agrees top and bottom within half an inch.
2. Solid at grade - tap around the base; rust-through where the post meets concrete is the usual failure.
3. In a footing, not just dirt. A post that moves when you lean on it will move under a gate.
4. Heavy enough for the new gate: a light post that carried a small aluminum gate will not carry a 14-foot steel panel with wood infill.

If one post passes and the other does not, a single swing hung on the good post is sometimes the cheapest fix. Otherwise replace: a new gate will never straighten an old post, and the gate will be blamed for it.

What to order

If you are buying the gate from us, add posts to the configuration and choose the wall by the table above; the price updates with the gate. If you have posts, order the gate to the opening you measured and set nothing until the instructions arrive with the exact spacing. Either way, the assistant can look at a photo of your posts and tell you whether they are worth keeping.