Fix a Door Latch That Won't Catch

Doors that won't latch are among the most irritating failures in a house. They swing open when you want privacy, let drafts through, and make closing a room feel like negotiating with broken machinery. The frustration compounds because the problem seems so simple—a small metal tongue should slide into a small metal hole—yet the door refuses to cooperate. Most latch failures come down to misalignment: houses settle, hinges sag, humidity swells wood, and what once lined up perfectly now misses by an eighth of an inch. The good news is that nearly every latch problem has a mechanical fix you can complete in under an hour with basic tools. The repair strategy depends on understanding what's actually failing. Sometimes the latch bolt strikes the plate but can't enter the hole. Sometimes it misses the plate entirely. Sometimes the bolt retracts but won't spring back out. Each scenario points to a different adjustment. The key is diagnosing the specific misalignment before you start moving metal around. Once you know where the gap is, the fix is usually just shimming a hinge, repositioning a strike plate, or filing a quarter-inch of metal to give the bolt the clearance it needs.

1. Find the misalignment first. Close the door slowly while watching the latch bolt meet the strike plate. Use a pencil to mark on the strike plate where the bolt actually hits. Check if the bolt is too high, too low, or missing the opening entirely. Also test if the bolt retracts and extends smoothly when you turn the knob—if it sticks, the problem is in the latch mechanism itself, not alignment.
2. Check hinges for sagging. If the latch hits too high or too low on the strike plate, the door has likely sagged on its hinges. Open the door and examine the gap between door and frame from top to bottom. An even gap means the hinges are fine. A wider gap at the top means the door has dropped. Tighten all hinge screws with a screwdriver—many latch problems disappear when loose hinges get snugged up.
3. Lift the door with shims. When the latch hits too low on the strike plate, the door needs to lift. Remove the screws from the bottom hinge on the door frame side. Cut a piece of cardboard the size of the hinge mortise and place it behind the hinge leaf as a shim. Reinstall the hinge with the shim in place—this tilts the door upward. Test the latch. Add more shims if needed until the bolt aligns with the strike plate hole.
4. Align the strike plate precisely. If the bolt hits the frame beside the strike plate instead of entering the hole, the plate needs to move. Remove the two strike plate screws and reposition the plate so the hole aligns with where the bolt actually hits. You may need to chisel the mortise deeper or wider to accommodate the new position. If the old screw holes show, fill them with wood filler, let dry, then paint to match the frame.
5. Open the strike plate hole. When the bolt enters the strike plate hole but doesn't slide smoothly, the opening is too small. Remove the strike plate and secure it in a vise or clamp it to a workbench. Use a metal file to enlarge the opening in the direction the bolt needs to travel—usually toward the door stop. File in one direction only, checking fit frequently. A small amount of filing goes a long way. Reinstall and test.
6. Free up the stuck bolt. If the bolt mechanism sticks or won't spring out when you release the knob, remove the interior knob and latch assembly from the door. Clean old grease and debris from the mechanism with a rag and spray lubricant. Work the latch back and forth to distribute lubricant. Check for bent parts or broken springs. Reassemble and test before reinstalling in the door.
7. Trim swollen wood carefully. When humidity swells a door, it may press against the frame before the latch can engage. Check for shiny spots on the door edge where it rubs. Mark these spots and plane or sand them down until the door closes without pressure. Remove the door from its hinges for easier planing. Test fit frequently—remove only as much wood as necessary for the door to close and the latch to engage.
8. Verify reliable latching. Close the door from various angles and speeds to confirm the latch catches reliably every time. The bolt should slide into the strike plate smoothly and click into place without force. If it catches only when you slam the door, there's still misalignment to correct. Make small adjustments until the door latches with a normal push. Mark the final strike plate position with pencil so you can return to it if future settling requires re-adjustment.