Driveway Gate Installation: Posts, Clearances and Sloped Driveways

A driveway gate is a lever hanging on a post. Almost every problem after installation, from a latch that no longer meets to a gate that drifts open on its own, traces back to the post, the footing under it, a clearance nobody planned, or ground that was never measured.

The hinge post does the work

As the posts and clearance guide explains, a swing panel's whole weight hangs on the hinge post and tries to bend it toward the latch. The latch post only holds a latch. On a dual swing, both posts are hinge posts. "Wall" means the thickness of the steel tube, and it is what resists bending.

If you are between the two, buy the heavier. The cost difference is small next to resetting a post. Sliders load posts differently: rollers carry the weight along a track, so the operator pad and the end posts are what need footings.

Footings that stay plumb

• Depth: 36 inches minimum for a typical swing gate, 42 to 48 inches for panels over 12 feet, heavy infill or an automated gate, and always below your frost line if that is deeper.
• Hole: 10 to 12 inches across, belled slightly at the bottom so the concrete cannot be levered up.
• Drainage: 4 to 6 inches of gravel under the post, with the top of the concrete sloped away so water sheds.
• Cure: 24 to 48 hours before the post takes a gate.

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

Spacing and the three clearances

A gate is built narrower than the opening so the hinges and the latch have room. The instructions that ship with the gate give the exact post-to-post number. Setting posts before the gate arrives saves a week, but set them to that number, not a guess, then check top and bottom until they agree.

Hinge side

Set by the hinge itself. Follow the gate's hinge instructions rather than a generic number.

Latch side

About three-quarters of an inch to an inch is typical: enough for seasonal ground movement, small enough to keep a hand out.

Ground

Two to four inches above the highest point the panel passes over. Measure across the whole arc, since a crowned driveway is higher in the middle.

Each swing panel also needs a clear quarter circle as wide as the panel, with no parked car, garage door path, planter or rising ground in it. Plan the arc on paper before the posts go in, because the hinge post's position sets where it lands.

Sloped driveways

A driveway that rises from the street is the most common reason a gate project stalls. The guide to a driveway gate on a slope explains why: a swing panel's bottom edge sweeps a flat plane, so rising ground stops it before it is fully open.

To measure, hold a 4-foot level on the ground at the high side, raise the low end until the bubble centers, and measure the drop. Multiply by the opening width divided by 4. Repeat along the swing arc at 4 and 8 feet out. With up to about 2 inches of rise over the arc and the gate opening downhill, a swing gate works. From 2 to 4 inches it is a compromise. Over 4 inches, or any rise when the gate must open uphill, choose a slider or cantilever. A cantilever needs about 1.5 times the gate width of straight fence line and costs 15 to 20 percent more than a tracked slider. Its roller posts must be set precisely, so we recommend a pro install for it.

A slope also leaves a wedge-shaped gap under a straight-bottomed gate. Because we size to the inch, a stepped bottom rail that follows your ground line is a quick ask once you have chosen the gate.

Reusing existing posts

Keep an old post only if it is plumb, solid at grade with no rust-through where it meets the concrete, set in a real footing, and heavy enough for the new gate. A new gate will never straighten an old post. If one post passes and the other does not, a single swing hung on the good post is sometimes the cheapest fix.