How do I keep a fence gate from sagging?

Keep the hinge post from moving, keep the frame square, and keep the wood dry. A gate that has all three rarely sags, and a quick check each spring and fall catches the small slips before the latch starts to drag. If your gate has already dropped, how to fix a sagging fence gate covers squaring it and fitting a brace or cable first.

Start with a hinge post that cannot move

Post strength is especially important for corner and gate posts,^[1] because the gate hangs all its weight off one post and levers on it every time it swings. Most gates that keep sagging are hanging on a post that is slowly tipping.

When a gate post is set or reset, the usual concrete-post method calls for a post hole three times the post's width and one-third to one-half of the post's above-ground length deep, plus 6 inches, with 6 inches of gravel or crushed stone in the bottom.^[2] Finishing the concrete so it slopes away from the post helps protect it from rot.^[2] Give the concrete time before the gate goes on: one gate maker says to set gate posts 2 to 3 days before the gate is hung, because of concrete cure times,^[3] and notes that a hinge post that is not tied to a fence panel may need extra stiffening.^[3]

For the post itself, the Forest Products Laboratory recommends pressure-treated wood for the high hazard of ground contact.^[6] Resetting a post means digging, and Virginia law requires a locate request to the notification center before any excavation.^[7] Virginia 811 asks homeowners to contact it three days before any digging project, fences included, and the service is free.^[8]

Keep the frame square

A gate is a rectangle that wants to become a parallelogram. Two things stop it.

A diagonal brace from the bottom corner on the hinge side up to the top corner on the latch side. In that direction it pushes the latch side up and carries the load into the bottom hinge. It should fit tight against the rails and be screwed to every board it crosses. A brace that runs the other way, from the top hinge corner down to the bottom latch corner, does little to stop the sag.

An anti-sag cable with a turnbuckle, running from the top of the hinge side down to the bottom of the latch side. For large gate panels, an anti-sag cable may be needed to stop the sag,^[3] even on a gate that already has a brace. The cable's advantage for upkeep is that it can be tightened again with a quarter turn.

Corner brackets add stiffness too: galvanized corner connectors in the frame's corners hold them at 90 degrees.^[4]

Use hardware that outlasts the wood

Hinges are where most of the gate's weight lands, so they should be rated for its size and fixed with long exterior screws into solid wood, not short screws into a board's edge. A tall privacy gate often needs three hinges rather than two.

Rust matters more than it looks. Metal connectors and fasteners can corrode and lose carrying capacity in corrosive conditions, and preservative-treated wood, soils and long periods of wetness are among the causes.^[5] Choose coated or galvanized hinges, brackets and screws rated for treated lumber, and replace any that are flaking or bent.

On a double gate, a drop rod on the inactive leaf drops into a hole or sleeve in the ground^[3] so that leaf stays put while the other swings. A missing or bent drop rod lets both leaves hang off their hinges and sag together.

Keep the bottom dry

Decay fungi need mild temperatures, moisture and air,^[6] and wood gets wet enough for serious decay only when rain, condensation or wet ground soaks it.^[6] On a gate, that means the bottom rail and the base of the hinge post. Leave clearance under the gate, keep mulch and soil pulled back from the post, turn sprinklers away, and keep a finish on the top edges and the bottom rail. Soft wood cannot hold a screw, and a gate whose hinge screws sit in rot will sag however well it is braced. How to make a wood fence last longer covers finishes and drainage for the rest of the fence.

A twice-a-year routine

Weather and temperature changes can mean periodic hinge adjustment to keep the latch connecting,^[3] so put the gate on the same spring and fall list as cleaning gutters. The steps on this page are a short job: check the post, tighten the screws, measure the diagonals, give the cable a turn, and clear the bottom. Discourage children from riding the gate as it swings, and do not hang heavy planters or bikes from it.

Stop and call a pro if

• The hinge post moves when you push it, is soft at the soil line, or has a crack running down from the hinges.
• The gate is a heavy drive gate, a double gate across a driveway, or has an electric opener.
• The gate is part of a swimming pool barrier and no longer closes and latches by itself.
• The frame is rotted at the bottom rail or stiles. Rebuilding the gate is usually the better repair.
• The gate post is part of a deck, porch or retaining wall rather than a freestanding fence.

For heavier repairs, browse fence repair businesses, all exterior answers, or exterior businesses around Blacksburg. To have it done, describe the gate once and local businesses send written quotes.