Deadbolt Hard to Lock? Check the Door Before the Lock
When a deadbolt runs freely with the door open but drags once the door is shut, we find it rubbing the strike plate it slides into. Loose hinge screws let a door drop, and a humid summer swells a wood door. Either one moves the bolt off the opening. Tightening the hinge screws often lifts a dropped door and frees the bolt.
Start with the door open. Turn the deadbolt out and back with the key, then with the thumb turn on the inside. The bolt should slide all the way out without catching. Now close the door and do both again, thumb turn before key. Try the key from outside only with someone inside or another door unlocked. We run this door-open test first on every house call about a stiff deadbolt.
If the bolt catches or the key turns hard only with the door shut, leave the lock alone and look at the door. A door that locks only after you lift or push it has the same trouble. Do not force the key. We pull snapped keys out of locks where someone forced a dragging bolt. Before you buy a new deadbolt for that door, read our guide to rekeying or replacing your locks. If the bolt drags with the door wide open as well, we turn to the lock.
How to tell a sagging door from a shifted strike plate
Close the door and look at the gap. It should run even down the latch side and across the top. If it pinches tight near the top of the latch side and widens across the top toward the latch, the door has sagged. The door maker Therma-Tru treats an uneven gap across the top as a sign of a door sagging out of square in its frame.
We look for worn paint or bare wood at the top corner on the latch side, where a sagging door rubs. Check the strike next. Fresh scrapes along the edge of its opening show where the bolt hits. A shiny streak on the bottom of the bolt means it has been riding the lower edge of the strike opening.
Then open the door halfway and lift up on the handle. If either half of a hinge moves, the screws need tightening. We check the top hinge first, because loose screws there let the latch side sink.
Last, mark the bolt. With the door open, run it out, rub lipstick or chalk on its end, and turn it back in. Painter’s tape over the strike keeps the mark off the finish. Close the door, then use the thumb turn to run the bolt gently against the tape. Stop where it resists, and turn the bolt back in before you open the door.
Read the mark against the strike opening. The home-repair site Bob Vila says a mark below the opening may mean sagging hinges. One above it more likely means the strike is in the wrong spot. On a door you have to push shut to lock, the mark lands beside the opening, on the side away from the weatherstrip.
| Where the mark lands | Where to start |
|---|---|
| Below the opening | Hinge screws, then one long screw in the top hinge |
| Above the opening | Snug the hinge screws, then adjust the strike. Skip the long screw, which would lift the bolt higher. |
| Beside the opening, away from the weatherstrip | Snug the hinge screws, then adjust the strike. |
| Centered, but the bolt stops short | Clear paint or chips out of the pocket behind the strike. |
Run the same test on a door that will not latch. Tape the strike the latch catches in, mark the latch’s angled tip, and close the door gently. A sagging door often drags at the latch as well. The hinge fixes free both.
Why a wood door binds in summer & loosens in winter
Wood takes on moisture from the air and gives it back as the humidity changes, according to the USDA Forest Products Laboratory’s Wood Handbook. A wood door swells in damp air and shrinks in dry air. So does a wood frame. The bolt then meets the strike in a different spot from season to season.
Every summer since 1983, we have found wood doors around Evansville swollen tight in their frames. The edge of the door rubs, and the bolt catches the edge of the strike unless someone pushes the door shut. Some fit again once the air dries out.
Winter heating dries indoor air enough to crack paint and furniture. Wood doors and frames dry out with it. Once the furnace runs, we see gaps open and doors rattle in their frames.
When a wood door binds only in humid weather, we leave the strike alone, because a strike filed to clear the swell lets the door rattle once the heat comes on. Spring and fall put the door between its summer and winter sizes. Adjust the strike then. If a front door is hard to lock only on freezing mornings, our post on frozen locks in a cold snap covers ice in the strike and what to leave alone.
How to fix a deadbolt that misses the strike plate
Work in the order that fits your mark. After each step, close the door and try the bolt again, and stop at the first one that frees it.
- Tighten the hinge screws. Work from the top hinge down. Snug every screw, on the frame side and the door side.
- If the mark landed low, put one long screw in the top hinge. Swap one screw holding the top hinge to the frame for a 3-inch screw whose head matches the old one, so it sits flush in the hinge. We use the hole farthest from the hinge pin, where it is most likely to reach the stud. It draws the frame toward the stud and can pull a sagging door back into line. Drive it a few turns, close the door, and check the gap. Stop once the gap runs even. Past that point, the latch side rises too far and the bolt rides high.
- Adjust the strike plate. Mark the bolt again, since the hinge work moves the door. If the strike moves under your thumb, snug its screws. Some entry doors have an adjustable strike, and Therma-Tru lists realigning one as a fix. Move it the way the door maker’s instructions show. A fixed strike that misses by an eighth of an inch or less can be filed on a mild spring or fall day. Take the strike off the frame and file the edge of its opening nearest the mark, a little at a time. Screw it back on and try the bolt after each pass.
When the key or bolt is stiff with the door open
If only the key is stiff while the thumb turn runs the bolt smoothly, we check the key and the cylinder it turns in for wear. We take the lock apart at the house when the bolt drags with the door open or the key spins without moving it. Inside, a part has usually worn, broken, or slipped out of place. We repair or replace that part. We also check how a new deadbolt was installed when it has stuck since the day it went in.
When to call a locksmith or a carpenter
We handle hinge screws that will not hold, a strike that has to move, and a lock that is stiff on its own. Some doors still meet the weatherstrip at the top or bottom first on a mild day. The latch side of that frame usually needs resetting on new shims, the wedges that hold it in place. That is carpenter’s work, and so is planing a wood door that rubs its frame all year. We will tell you on the phone when a job sounds like carpentry. Call us when any of these turn up:
- A hinge screw spins and will not tighten.
- The mark misses a fixed strike by more than you can file. Moving the strike that far means cutting new wood in the frame.
- The bolt clears a filed strike but still hits the wood behind it.
- The mark sits centered and the pocket is clear, but the bolt still stops short. The pocket needs drilling deeper. We treat a bolt that stops partway as an unlocked door.
- The bolt still binds after the fixes.
- The bolt or key is stiff even with the door open.
- An outside door will not lock at all. If lifting or pushing the door lets the bolt run all the way out, lock it that way until the door is fixed. To unlock it, lift or push the door the same way so the bolt slides back without force. Show everyone in the house how.
When you call A-1 Lock & Safe, tell us what the bolt does with the door open and with it shut. If it sounds like a loose hinge screw you can tighten yourself, we will say so. Anything more, we quote from what you describe. We check the cause at the door before we start.