Fix a sagging door in twenty minutes with the hinges still on

Quick answer: Close the door slowly and find where it rubs. Tighten every hinge screw. If the screws just spin, replace the top hinge's jamb-side screws with 3-inch ones that bite the framing. Still tight? Shim the bottom hinge with cardboard or plane the rubbing spot. The door stays on its hinges the whole time.

A door that binds at the top corner on the latch side is almost always a top hinge that has pulled loose. The weight of the door levers on that hinge every day, and the short screws only hold the thin trim jamb, not the framing behind it. Over a few years the jamb gives a little, the door drops, and the corner starts dragging.

Most people respond by shoving harder or reaching for a plane. Don't. Fix the cause first, and the plane may never come out.

What you need

• A screwdriver that fits your hinge screws, usually a #2 Phillips. A hand driver, not an impact driver.
• A drill with a 1/8-inch bit
• Three or four 3-inch wood screws, #8, with heads that sit in your hinge holes
• Two wood shims, or a pry bar, to support the door
• A cereal box and scissors
• A pencil, safety glasses, and a block plane or sanding block with 80-grit paper, only if you need them

Read the door before you touch it

Close the door slowly and look at the gap around it, called the reveal. It should run about 1/8 inch all the way around and look even.

A sagging door tells on itself. The gap along the top is wide on the latch side and tight on the hinge side, or the reverse of what it should be. Or the gap at the top latch corner has vanished and the door scrapes there. If you can't tell by eye, slide a folded piece of paper along the gap. Wherever it pinches, that's your problem.

Also open and close it a few times. Watch the hinges. If the top one visibly moves or the leaf wobbles against the jamb, you've found the culprit.

Take the weight off

Open the door about halfway. Slide a shim or the tip of a pry bar under the latch edge and lift just enough to take the load off the hinges. You're not raising the door. You're keeping it from swinging on loosened screws.

Wear safety glasses. A screw that snaps or a shim that kicks out will go for your face.

Tighten everything first

Start with the top hinge, then the middle, then the bottom. Check both leaves of each hinge, the one on the door and the one on the jamb.

Snug is the goal, not crushed. If a screw turns forever without tightening, the hole is stripped. That's the usual story, and it leads to the real fix.

The long-screw fix

This is the move that actually cures a sag, and it works with the hinge staying right where it is.

Take out one screw at a time from the jamb-side leaf of the top hinge. Remove the one nearest the door's top and leave the other two in. The hinge stays held and the door stays hung.

Drill a 1/8-inch pilot hole straight through the empty screw hole, about 2½ to 3 inches deep. You're drilling through the jamb and the gap behind it into the wall framing. You'll feel the bit bite into solid wood after a short stretch of nothing.

Drive in a 3-inch screw. As it tightens it pulls the jamb back toward the framing, and the door lifts a hair with it. Stop when it's snug. Over-tightening can bow the jamb, and you'll have traded one binding spot for another.

Repeat for the second screw. Many people stop at two. Do the third if the hinge still feels loose.

Check the door. If it swings and latches clear, you're finished. Don't plane a door that just needed its hinge fixed.

If the hinge hole is stripped on the door side instead, pack it with a couple of wooden toothpicks dipped in wood glue, snap them off flush, and let it dry before driving the screw back in. That's slower, but it works on a door you can't afford to wait on.

Shim the bottom hinge

Sometimes the door is tight at the top latch corner even after the screws are solid. The jamb has settled a little. A thin shim behind the bottom hinge swings the top corner clear.

Loosen, but don't remove, the three jamb-side screws on the bottom hinge. Back them out about four turns. Cut a rectangle of cereal-box cardboard the size of the hinge leaf and cut a slit from one edge to each screw hole so it slides in around the screws. One layer is a bit under 1/32 inch, which is usually plenty.

Slide it behind the leaf. Snug the screws. The hinge now sits a hair farther out, and the door rotates slightly, freeing the top latch corner. Try the door before adding a second layer. Two is the practical limit, and if you need more, the jamb needs a carpenter's eye.

The reverse problem is a door rubbing low on the latch side. Shim the top hinge instead.

Plane it only as a last resort

If it still binds, mark the spot. Run a pencil along the rubbing edge, close the door, open it again, and see where the lead transferred. That's the high spot. Take off only that.

Before you cut anything, check the age of your house. If it was built before 1978, the paint may contain lead. Dry sanding or planing paint creates dust you don't want in the air or on your kids' toys. Test the paint with a lead check kit from the hardware store, or follow EPA guidance for lead-safe work, before you start. Wear a real respirator, not just a dust mask, if the test comes back positive.

With the door still hung, use a sharp block plane with light passes along the latch edge, or a sanding block with 80-grit paper. Take off a little and test. You can always remove more. You can't put it back.

Then seal any bare wood with paint or polyurethane. Raw edge grain sucks up humidity and swells, and you'll be back with the plane in August.

A cut hand is a real possibility with a chisel or a plane. Know what to do before the first drop of blood, and keep the ten-minute response routine in your head.

If the latch is the problem

Sometimes the door doesn't bind. It just won't catch. Close it and look at where the latch bolt hits the strike plate on the jamb. If the bolt sits high or low, loosen the strike plate screws and shift it, or file the opening slightly larger with a flat metal file. Fix it before you tighten the door's fit.

If your door has an electronic keypad, a wired strike, or a doorbell wire running into the jamb, kill the power first, and read which wiring jobs to do yourself before you drill into the frame.

Leave it better than you found it

Put a drop of light machine oil or silicone spray on each hinge pin and work the door back and forth until it stops squeaking. Wipe off the excess so it doesn't drip on the floor. Sweep up the dust, pocket the cardboard scraps, and put the shims back in the drawer.

If you're renting, mention it to the landlord. They'll thank you for fixing it, and it keeps your record clean.

A door that closes with a quiet click is one of those small things a house gives back every day. You'll notice it the first time you carry a laundry basket through without kicking the bottom.