Fence Gate Installation Guide: Hinges, Latches and a Gate That Stays Square

A fence gate that stays square for years comes down to three decisions made before the first screw goes in: hinge posts set in concrete at least 30 in deep, adjustable hinges rated for the gate's actual weight, and a diagonal brace that carries the load from the hinge side down to the latch side — skip any one of those and the gate will sag, drag, and stop latching within a year. Plan the opening with the Fence Calculator, measure the gate and the post spacing with the Square Footage Calculator, compare fence project costs in the fence installation cost guide, and pair this with the fence buying guide so the gate matches the fence it hangs on.

Hinge posts first: the gate is only as strong as what it hangs from

Set the hinge post like a foundation, because the hinge post carries the entire weight of the gate — a 4 ft wide wood gate weighs 40 to 60 lb, a 6 ft wide gate weighs 60 to 90 lb, and a 10 ft double gate can weigh 150 lb or more — and every pound hangs off two hinge points that lever against the post all day, every day. Dig the hinge post hole 30 to 36 in deep (below the frost line in cold climates, where frost heave will lift a shallow post and rack the gate out of square in a single winter), 12 in in diameter for a 4x4 post and 14 in for a 6x6 post, and set the post in concrete with 2 to 3 in of gravel at the bottom for drainage. Use a 6x6 post for any gate wider than 5 ft, for double gates, and for metal or vinyl gates that concentrate their weight on the hinges — a 4x4 post flexes under a heavy gate, and a flexing post is a gate that never latches cleanly. Brace the hinge post to the next fence post with a horizontal rail or a diagonal brace during the concrete cure, because a post that leans even 1/2 in while the concrete sets will haunt the gate forever. Let the concrete cure a full 24 to 48 hours before hanging the gate: a gate hung on green concrete pulls the post out of plumb, and no hinge adjustment fixes a post that cured crooked.

Choose the post material for the gate's life, not just its price: pressure-treated pine posts cost $15 to $30 and last 15 to 20 years in the ground when the below-grade portion is rated for ground contact, cedar posts cost $25 to $50 and resist rot naturally but are softer and hold screws less firmly, and steel posts (galvanized or powder-coated) cost $40 to $80, never rot, and hold heavy gates without flexing — the best choice for wide or metal gates. Whatever the material, keep the bottom of the post from sitting in standing water: grade the soil away from the post base, and never let mulch or soil pile against the post above the concrete, because trapped moisture rots wood posts at the soil line, which is the most common failure point in a fence. Check the post with a level on two faces before the concrete sets, and re-check it after the gate is hung and loaded, because a post that looks plumb empty can lean 1/4 in under a 60 lb gate.

Hinges: rated weight, adjustable, and mounted to structure

Buy hinges rated for at least twice the gate's weight, because the rated weight on a hinge assumes perfect installation and still air, while a real gate gets slammed by children, pushed by wind, and loaded with snow and ice — and a hinge rated exactly at the gate's weight will sag within a season. A pair of strap hinges ($15 to $40 per pair) suits light wood gates up to 50 lb; heavy-duty T-hinges or adjustable strap hinges ($30 to $80 per pair) suit gates from 50 to 150 lb; and ball-bearing hinges ($40 to $100 per pair) are the right choice for metal gates and any gate over 100 lb, because the ball bearings carry the load without binding and keep the gate swinging freely for years. Use three hinges on any gate taller than 5 ft or heavier than 75 lb — the third hinge, mounted at the center, stops the gate from twisting, which is the failure mode that makes a tall gate bind at the top and drag at the bottom. Mount the hinges through the gate frame and into the post with lag screws or through-bolts, never with short wood screws into a single board: a hinge screwed into a single picket or a thin rail will pull out, while a hinge bolted through the gate's structural frame and into solid post wood holds for decades. Use stainless steel or hot-dip galvanized fasteners — plain zinc screws rust in a year outdoors, and a rusted screw head is a hinge that cannot be adjusted or removed.

Choose adjustable hinges whenever the budget allows, because every gate sags a little as the wood seasons and the post settles, and an adjustable hinge lets you lift the latch side by 1/4 to 1/2 in with a wrench instead of rebuilding the gate. Self-closing hinges ($25 to $60 per pair) are required by code for pool gates in most jurisdictions and are worth fitting on any gate that should stay shut — a gate that self-closes is a gate that cannot be left open by a child or a gust of wind. Set the hinge gap at 1/4 to 3/8 in between the gate and the hinge post: too tight and the gate binds when the wood swells in summer humidity, too wide and the gate wobbles and the latch misses. Hang the gate with a 1/2 in gap at the bottom so it clears grass, snow, and uneven ground, and with the top rail level — a gate hung level on a post that is plumb will swing true; a gate hung to match a leaning post will always fight its hinges.

The diagonal brace: the one piece that stops sagging

Build the diagonal brace correctly, because the diagonal brace is the structural heart of a wood gate — it is the only piece that stops the gate from sagging into a parallelogram under its own weight. The brace must run from the bottom of the hinge side up to the top of the latch side, forming a Z or a compression diagonal that pushes the latch side up: a brace installed the other way (top hinge side to bottom latch side) pulls the latch side down and makes the sagging worse, which is the single most common gate-building mistake. Cut the brace to fit snugly between the horizontal rails with no gaps, and fasten it with screws through the rails into the brace ends, not just with glue or nails. For a gate wider than 5 ft, add a second diagonal or a vertical center stile to split the span — a single diagonal cannot carry a 6 ft gate's weight alone, and a wide gate without a center stile will sag at the middle rail. A metal anti-sag kit ($15 to $30) is a legitimate shortcut: a turnbuckle and cable that runs from the top hinge corner to the bottom latch corner and can be tightened as the gate seasons, which lets you correct sag in minutes with a wrench instead of rebuilding the frame.

Build the gate frame from straight, dry lumber and assemble it on a flat surface, because a gate built on a warped bench or from bowed boards will never hang square. Use 2x4 rails and stiles for a standard gate (2x6 for gates over 5 ft wide), join them with half-lap or mortise joints where possible, and screw every joint — nails work loose as the wood moves through wet and dry seasons, while screws hold. Check the frame for square by measuring both diagonals: if the two diagonal measurements match within 1/8 in, the frame is square; if they differ by more than 1/4 in, rack the frame until they match and then fit the diagonal brace to lock it. Leave a 1/2 in gap on the latch side and a 1/4 to 3/8 in gap on the hinge side so the gate clears the posts when the wood swells in humid weather — a gate built tight in winter will bind solid by July.

Latches and the final fit: a latch that clicks every time

Fit the latch last, after the gate is hung and swinging freely, because the latch is an adjustment, not a structural fix — a latch fitted to a sagging gate only masks the sag until the screws pull out. Set the latch at a comfortable height, typically 36 to 48 in from the ground, and mount the latch body on the gate and the catch on the latch post so the latch bolt drops into the catch with the gate fully closed and no lifting or pushing required. A gravity latch ($10 to $25) is the simple, reliable choice for a garden gate; a thumb latch ($20 to $40) gives a cleaner look and a one-handed operation from either side; and a keyed or padlockable latch ($25 to $60) is the right choice for a gate that secures a yard with a pool, a dog, or expensive equipment. For pool gates, the latch must be self-latching and mounted at least 54 in above the ground (or on the pool side of the gate) to meet most codes — check the local code before buying hardware, because a pool gate that fails inspection costs more to fix than the hardware saved. Test the latch 20 times in a row after fitting: open the gate, let it swing shut on its own, and confirm the latch catches every time without a push. If it misses once in 20, adjust the hinges or the catch — a latch that works 19 times out of 20 fails on the day it matters.

Finish the gate the same way you finish the fence: seal or stain all six sides of every board, including the bottom edge and the end grain, because the bottom edge is where water sits and rot starts. A gate that is sealed on the faces but raw on the bottom edge will rot from the bottom up in 3 to 5 years while the fence beside it lasts 15. Lubricate the hinges and the latch with a silicone spray twice a year, and check the hinge screws every spring — a screw that has backed out 1/8 in is a hinge that is about to pull free. Keep a spare hinge and a handful of matching screws in the garage: a gate that breaks on a Saturday is fixed in 20 minutes with the parts on hand, or in two days with a trip to the store.

Common gate problems and how to fix them

Fix a sagging gate by adjusting the hinges first, because most sag is a hinge problem, not a frame problem: loosen the hinge screws, lift the latch side to level with a wedge or a helper, and re-tighten. If the hinges are already at their limit, fit an anti-sag turnbuckle kit ($15 to $30) and tighten the cable until the gate is level — a quarter turn at a time, checking with a level after each adjustment, because over-tightening racks the gate the other way. If the gate still sags after the hinges and the turnbuckle are maxed out, the frame itself has racked: remove the gate, lay it flat, rack it back to square (diagonals equal within 1/8 in), and refit or add a diagonal brace. A gate that drags on the ground usually has a post that has leaned or heaved: check the hinge post with a level, and if the post has moved, the fix is to reset the post — digging it out, re-plumbing it, and re-pouring concrete — because no hinge adjustment compensates for a post that is 1 in out of plumb.

Fix a gate that will not latch by checking the gaps before touching the hardware: a gate that is level but still misses the catch usually has a latch post that has moved, or a catch that was fitted when the wood was dry and now misses because the gate has swollen. Move the catch, not the latch, and elongate the screw holes in the catch plate with a file so the catch can be adjusted in 1/8 in increments. A gate that sticks in summer and swings free in winter is a moisture problem, not a hardware problem: plane 1/16 in off the latch-side stile, reseal the cut edge, and the gate will clear through the humid season. A gate that slams in the wind needs a gate stop — a small block on the latch post that the gate rests against when closed — plus a self-closing hinge with an adjustable tension screw set to close the gate firmly but not slam it. A gate that rattles in the wind has too much play in the hinges: tighten the hinge screws, add a third hinge, or replace worn hinges whose pin holes have elongated.

Costs, lifespan, and the final check

Budget a gate as a project, not as an afterthought: a DIY wood garden gate (4 ft wide, 4 ft tall) costs $150 to $400 in materials including the hinge post, hinges, latch, and stain; a 6 ft privacy gate costs $250 to $600; a double driveway gate (10 to 12 ft) costs $500 to $1,500 in materials; and professional installation adds $200 to $600 for a single gate and $500 to $1,500 for a double gate, depending on whether the posts need setting. A well-built wood gate lasts 10 to 15 years with the fence, a vinyl gate lasts 20 to 30 years, and a steel or aluminum gate lasts 25 years or more — but every one of them lasts half as long if the hinge post is shallow, the hinges are undersized, or the diagonal brace runs the wrong way. Run the final check before calling the job done: the gate swings freely through its full arc without binding, it self-closes and latches on its own from a half-open position, the gaps are even (1/4 to 3/8 in hinge side, 1/2 in latch side, 1/2 in at the bottom), the diagonal brace runs from the bottom hinge side to the top latch side, and the post is plumb with the concrete fully cured. Write the install date on the inside of the gate frame with a permanent marker, and set a calendar reminder for the spring hinge check — the gate that gets a 5-minute check every spring is the gate that still latches in year 10.