Fix a uPVC door that's hard to lock

Diagnose why the door won't lock, then adjust the hinges and keep plates so it locks smoothly again.

DR-01Work out what's actually wrongOpen the door and check if it drags on the frame, sags at the top corner, or feels tight only near the bottom. Then try the key with the door held tight shut by hand — if it locks easily that way, the door has dropped and the hooks or rollers no longer line up with the keeps. If the key is stiff even when the door is held shut, the problem is more likely the lock mechanism or the keeps themselves.

DR-02Check the hinges for wear or loosenessLift the door slightly by the handle while it's open — noticeable movement at the hinges means they need adjusting or tightening. Most uPVC doors have adjustable hinges with small screws or an Allen key socket on the hinge itself, usually 4mm hex. Tighten any loose hinge fixing screws into the frame first before adjusting anything else.

1 each · Allen key set (hex 2.5–6mm)

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DR-03Adjust the hinges to lift or square the doorMost uPVC hinges adjust in three directions: a vertical screw to lift a sagging door, a lateral screw to pull it tighter to the seal, and a compression screw to squeeze the door in against the frame. Turn each adjuster a quarter turn at a time, then close the door and try the key. Small adjustments make a big difference — don't over-tighten in one go.

DR-04Check and adjust the keepsThe keeps are the metal plates on the frame that the lock's hooks, rollers or bolts engage into. With the door open, look for scuff marks on the keep showing where the hook is actually hitting versus where it should sit centrally. Loosen the keep's fixing screws slightly and tap it a millimetre or two in the direction needed, then retighten and test the lock.

1 each · Pozidriv screwdriver

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DR-05Lubricate the lock and moving partsSpray a PTFE-based lubricant (not WD40, which attracts grit and dries out) into the keyway, over the hooks and rollers on the door edge, and into the hinge pivots. Work the key and handle a few times to spread it through the mechanism. Wipe off any excess so it doesn't attract dust.

1 each · PTFE lock lubricant spray

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DR-06Test the full locking cycleClose the door normally (not slammed) and turn the key fully both ways, checking the handle lifts smoothly to engage the hooks or rollers before locking. Repeat from both inside and outside if the door has external access. If it still binds, go back and fine-tune the hinge and keep adjustments rather than forcing the key.

DR-07Tidy up and check for any replacement parts neededIf the keeps are badly worn, cracked, or the hooks are visibly damaged, replacing them is straightforward but needs the exact part matching your lock brand — take the old one to a locksmith or hardware shop for a match rather than guessing. Wipe down the door edge and frame to remove any lubricant overspray, and put tools away.

1 each · Replacement keep/strike plate (if needed)

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