A Sagging Gate Is Three Problems, Fixed In Order

You know the sound. That low scrape as the bottom corner of the gate drags an arc into the dirt, and the little hop you do with your knee to get the latch to line up. You've been doing it for two years. It takes about four hours to never do it again.

Before you touch a tool, figure out which of the three things is actually broken. A sagging gate is always the post, the hinges, or the frame itself. Fix them in that order, because fixing the frame on a leaning post is a waste of a Saturday.

Safety, briefly. A six-foot cedar gate weighs 60 to 90 pounds and it wants to land on your foot. Boots, not sneakers. Eye protection when you're driving screws into old dry wood, because the heads shear and the splinters fly. And if you're taking the gate off its hinges, have a second pair of hands or a sawhorse ready, not a plan involving your knee.

Ten minutes of diagnosis

Close the gate and latch it if it still latches. Now look at the gap on the latch side, top and bottom.

If the gap is even top to bottom but the whole gate sits low, your hinge post is leaning. If the gap is wide at the top and pinched at the bottom, the gate has racked out of square, or the hinges have pulled. Those look identical from ten feet away and they're entirely different repairs.

Put a two-foot level on the hinge post, both faces. More than a quarter-inch out of plumb over two feet and the post is your problem. Grab the post at shoulder height and push. If it moves, the concrete has cracked or the post is rotten at grade. Stab a screwdriver into the post an inch above the soil. If it sinks in like a wet sponge, you're not fixing a gate today. You're replacing a post.

Next, the hinges. Wiggle the gate up and down at the latch corner. If the movement is all happening at the hinge leaf, look at the screws. Nine times out of ten somebody hung a heavy gate with the 3/4-inch screws that came in the little bag, into end grain, and the wood gave up.

Last, the frame. Measure the gate diagonally, corner to corner, both ways. A square gate reads the same number both directions. If your diagonals differ by half an inch, the gate is a parallelogram now, and no amount of hinge tightening will help.

The post comes first

If the post is leaning but sound, dig out a foot of soil on the side it's leaning toward, push it plumb with a pry bar or a car jack against a block, and hold it with two temporary 2x4 braces staked into the ground. Then backfill with gravel in three-inch lifts and tamp each one hard with the end of a 4x4. Gravel drains. That's the whole trick.

A rotten post gets replaced, full stop. Cedar or pressure-treated rated for ground contact, and set your new one at least a third of its length in the ground with gravel underneath so water never sits on the bottom.

If the post is fine but slightly springy, a diagonal strut from the top of the hinge post back to the base of the next post in the fence line will stop it cold. Ugly? A little. It works.

Hinges that hold

Take the gate off. Set it flat on sawhorses where you can work on it, and get the old hardware out of your way.

Now upgrade. Whatever came with the gate is probably too small. On a full-height privacy gate, run three hinges, not two, and make them strap hinges long enough to reach across the gate's vertical stile and land on the horizontal rail. Heavy T-hinges or a proper strap set spread the load across two boards instead of trying to hold everything with one line of fasteners.

Screws matter more than hinges. Throw away the short ones. Use 2-1/2 to 3-inch structural screws with a real hex or star drive into the gate frame, and 5/16-inch by 4-inch lag screws into the post. Pre-drill everything with a bit slightly smaller than the screw's shank, especially in cedar, which splits if you look at it wrong.

Old stripped holes aren't a lost cause. Squeeze wood glue in, tap in a hardwood dowel or a couple of golf tees, snap them flush, let it cure an hour, then drill fresh. That repair outlasts the original.

And set your drill's clutch down. Driving a lag until the drill grunts is how you strip a hole you just fixed.

Squaring the frame, and which way the brace goes

This is the part people get backwards, and it's the reason so many gates have a brace on them and still sag.

A wood brace works in compression. It runs from the bottom corner on the hinge side, up to the top corner on the latch side. It props the latch side up. Cut a 2x4 to fit tight between the rails, tap it home with a mallet, screw it off.

A steel cable works in tension. It runs the opposite way, from the top corner on the hinge side down to the bottom corner on the latch side, and pulls the sagging corner back up. Anti-sag kits run about $20 at any hardware store and include two corner brackets, cable, and a turnbuckle.

Put the cable in the compression direction and you've hung a decorative wire on your gate. That's all it does.

Before you tighten anything, get the gate square. Lay it flat, measure both diagonals, and put a bar clamp across the long one. Crank until the numbers match within an eighth of an inch. Then install your brace or cable while it's held there. With a turnbuckle, snug it by hand, then give it a quarter turn at a time with a screwdriver through the barrel, checking the diagonals as you go. You can absolutely over-tighten a turnbuckle and rack the gate the other way. Slow is fine.

Rehanging it right

Set the gate back in the opening on blocks. Shim the bottom so you've got at least two inches of ground clearance, and more if your ground rises as the gate swings. A 3/8-inch gap on the latch side is plenty. Half an inch if the gate's a swelling wood species and you live somewhere humid.

Check plumb on the gate itself, not just the gap. Then drill and drive the post-side lags, top hinge first, and hang your weight on the latch corner before you commit to the rest. If it drops, you'd rather know now.

The latch goes on last. Always last. Anybody who mounts the catch before the gate is hanging square is going to mount it twice.

The one that doesn't get fixed

If the bottom eight inches of the gate stiles are soft and dark, the fasteners have nothing to bite. Cable it, brace it, lag it, and in a year you'll be back with the same scrape in the dirt. Build a new gate out of 2x4s with a compression brace built in from day one, and hang it on three strap hinges. It's a two-hour build and it'll outlive the fence.

One more thing. Your kids are going to ride that gate like a carnival attraction. So did you. Add a spring closer and check the lags every spring, and let them.