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LOCKS & HANDLES

Door Lock Stiff

A stiff lock can be caused by poor door alignment, dirt inside the cylinder, a worn key, cold weather or wear in the lock mechanism.

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Stop if the door cannot be secured

Do not force keys, handles or multipoint locks. External doors, fire doors and security hardware should be left safe and secure while repairs are arranged.

MOST LIKELY CAUSES

Start with alignment, fixings and the moving mechanism

Door misalignment The latch or bolt is under pressure in the keep.
Contamination Dust or debris increases friction.
Worn key or cylinder Pins and key surfaces no longer move cleanly.
Incorrect lubricant Heavy oil attracts dirt or gums up the lock.
◫ Symptom variations Match the handle, latch or locking behaviour. ⌄
  • Key turns more easily with door open
  • Lock is stiff in cold weather
  • Key needs wiggling
  • Bolt binds in the frame
  • Problem is getting gradually worse
✓ Quick checks Safe checks before dismantling anything. ⌄
  1. Test the lock with the door open.
  2. Try a spare key in good condition.
  3. Check latch and bolt alignment.
  4. Inspect the key for bends or wear.
  5. Avoid forcing the key.
Important: Test operation with the door open where possible. This separates alignment faults from lock or handle faults.
1 Step 1 — Rule out alignment Make the smallest safe correction and retest. ⌄

Compare operation with the door open and closed.

2 Step 2 — Clean and lubricate correctly Make the smallest safe correction and retest. ⌄

Use a lock-approved dry or specialist lubricant.

3 Step 3 — Repair worn hardware Make the smallest safe correction and retest. ⌄

Adjust the keep or replace worn cylinder or lock parts.

⌁ Why the problem happens How alignment, wear and internal components affect operation. ⌄

Even a healthy lock becomes stiff when the door presses sideways on the bolt. Internal dirt and worn keys create additional resistance.

⌘ Advanced checks Further diagnosis for persistent faults. ⌄
  1. Check multipoint hooks and rollers.
  2. Inspect cylinder retaining screw.
  3. Check handle lift operation.
  4. Measure door compression against seals.
  5. Inspect lock case for wear.
◇ Tools and information needed Useful items for accurate checks. ⌄
  • Spare key
  • Screwdrivers
  • Lock lubricant
  • Pencil
  • Torch
▣ Parts that may need replacing Common hardware linked to this fault. ⌄
  • Cylinder
  • Lock case
  • Keep or strike plate
  • Key
  • Multipoint gearbox
! When to call a professional Conditions that should end basic DIY diagnosis. ⌄
  • The key may snap.
  • The lock secures an external door.
  • A multipoint mechanism is stiff.
  • The cylinder is damaged after attempted entry.
  • The door cannot be locked reliably.
? Frequently asked questions Common lock and handle questions. ⌄

Why is it easier with the door open?

That strongly suggests alignment or seal pressure.

Can I use WD-40?

Use a lubricant specifically suitable for the lock type.

Should I force a stiff key?

No. A broken key can make the repair much harder.