Adjust a Sagging Door

From humidity, to loose screws, to a settling foundation, a variety of factors can cause a sagging door. A sagging position can create gaps, allowing drafts to blow through, or prevent it from lining up with the latch plate and closing correctly. The typical fix for a sagging door is to remove it from the frame, sand or plane, then refinish and repaint. However, this solution can be time consuming and a lot of work. Worse, if you sand or saw too much of the door during a humid season, you could be stuck with large gaps when it becomes less muggy. Before taking your door off its hinges, try some tricks to fix a sagging door, and potentially save time, work, and frustration.

Steps

Inspecting the Door, Hinges, and Frame

1. Find the sagging door’s cause. Inspect the door from inside, or the side from where you can see the hinges. Locate the gaps and where the door is tight. It’s common in sagging doors for the hinge side at the bottom to be tighter against the frame. The opposite side, or strike side, is often gapped at the top and tight where the door meets the sill.
2. See if the door and frame are level. Use a bubble level and carpenter’s square to determine if the door frame itself is level. Hold the bubble level against the door jamb’s left and right sides and top, and check to see if the bubble settles between the viewer’s two lines. You can hold the carpenter’s square, or steel square, to the door jamb’s four corners to determine if they deviate from 90 degrees.
   • You might find that the door is level, but the frame is off square. If the frame is out of square, you might have other problems, like a shifted wall or settling foundation.
   • In this situation, you might find planing to be your only solution.
3. Check and tighten all hinge screws. With the door open, and starting with the top, see if the hinges and screws are still tightly embedded in the door and jamb. Use a screwdriver, not a drill, to tighten all the screws, but take care not to overtighten them. If the screws give your driver resistance and the hinges are securely in place, they’re tight. Overtightening could strip the holes or push the door further out of alignment.

Replacing and Adjusting Hardware

1. Look for and fill stripped holes. If you find a stripped hole, place a doorstop under the open door to hold the temporary drop of the weight. Remove the hinge with the stripped hole by removing the screws holding it in place from the door jamb and frame, and if necessary, from the door’s face. Dip a toothpick or a matchstick into carpenter's glue and insert it into the hole. Use an amount of filler appropriate for how large the hole has become. When the glue dries, predrill a hole with an appropriately sized bit, then replace the hinge and its screws.
2. Replace short hinge screws with longer ones. If you’ve gone through a basic check and tightened hinges, but your door still sags, your screws might not be long enough. Remove a screw from the top hinge. If it’s not 2 1/2 to 3 inches long, the screw won’t be able to reach the wall stud through the jamb, so the door’s weight won’t be fully supported. Remove the old screws, and pre-drill into the jamb and wall stud before replacing them with longer ones.
   • Check the level of the door after replacing each screw
   • Remember not to overtighten.
3. Add shims between the hinge and the doorjamb. Make shims with thin pieces of cardboard, wood, or playing cards to fit between the hinge and jamb and help align the hinge and door. Remove the appropriate hinge, often the top hinge, and trace and cut out its shape from your shim material. Use the thinnest materials possible so you can add layers to the hinge mortise one at a time until the door is level again.
   • You might have to install shims on more than one hinge.
   • This technique involves some guess and check work. Adding or subtracting shims until the door is square might be necessary after each shim adjustment.

Sanding or Planing the Door

1. Scribe the door. If you’ve tightened or replaced screws, filled stripped holes, and tried shims, but the door still sags, you’ll have to plane or sand. Scribing, or marking, the door will give you the line at which you stop removing wood by planing or sanding. First, use a carpenter’s compass to draw a line an 1/8 inch from the edge on the side of the door that rubs against the jamb. Trace the line with masking or painter’s tape to make it more visible.
   • A carpenter’s compass is the easiest tool to use, and is inexpensive. If one’s not handy, use a pencil and straightedge.
   • Fix the masking tape to inside of the line you marked off: for example, if you scribed the left side of the door, fix the tape to the right side of the line.
2. Remove the door. Unscrew the hinges from the door face. Store the screws in a safe place, or tape them to the door face for safekeeping. Take the door to an open area, like a garage, and store it on a level surface, like sawhorses or a worktable.
3. Sand or plane the scribed edge. Using a belt sander is a great option. For the first 1/16 inch, use a 50-grit sanding belt. Keep the sander moving so you don’t wear a hole in one spot. Switch to 80-grit for the second half, then a 120-grit belt when you’ve gotten to the line in order to smooth it out.
   • Remember, the humidity that causes the door to swell and stick at the bottom may disappear and leave the door too short during dry spells. Don’t remove too much of the door.
   • You might reattach the door and find you haven’t planed enough, in which case you’ll have to repeat the process one or more times. Remember you can take away more door but you cannot put back what you’ve already removed, so sand carefully.
   • If you’re sanding the latch edge of the door, be sure to first remove the latch hardware. You may have to use a sharp chisel to dig out the latch hole so it doesn’t protrude from the door after planing.
4. Refinish and repaint the sanded edge. When you’ve determined that the door has been properly planed, remember to refinish and repaint the raw edge. Don’t do so until you’re sure you’ve finished sanding. A coat of varnish and paint will help prevent moisture from penetrating the wood, so you’ll be far less likely to have to fix a sag in the future.

Tips

• Find a helper to make the work of manipulating the door easier
• It’s better to guess and check and repeat processes than to, for example, sand too much door or overtighten a screw. You could damage hardware or have to buy a new door and jamb.

Warnings

• Be careful when handling power tools and sharp objects.
• Wear protective goggles when using sanding equipment.

Things You'll Need

• Bubble level
• Screwdriver
• Toothpicks or matchsticks
• Carpenter's glue
• 2 1/2-inch or 3-inch screws
• Drill
• Shims
• Carpenter’s compass
• Sandpaper
• Belt Sander & Belts
• Wood filler
• Varnish
• Paint

Related Articles

• Unstick a Door
• Install a Door Latch Attached Mortise Plate

Sources and Citations

See also

• Replace a Doorbell Chime
• Keep Windows from Fogging
• Clean Wood Doors
• Apply WD‐40 to Door Hinges
• Hang a Prehung Door
• Replace Old Double Hung Windows With Vinyl Replacements
• Install an Interior Door
• Repair a Damaged Hollow Core Door
• Install Glass Block Windows
• Replace a Pre Hung Door

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