Why does my door lock get harder to turn in humid weather?
Humid air makes a wooden door swell slightly, so the latch or deadbolt no longer lines up with the frame and rubs as it moves. The other common cause is grit or corrosion inside the cylinder, which damp air makes stickier.
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The useful question is which of the two it is. If the key turns stiffly even with the door open, the problem is in the lock. If it only sticks with the door shut, the door and frame are the likely cause.
Why humidity makes a lock stiff
Wood takes on moisture and gives it back with the seasons. In damp weather a door can grow a little and shift in its frame. The bolt then meets the edge of the strike plate or the hole in the frame at a slight angle, and the key has to work against that friction.
Inside the lock, the cylinder collects dust, grit and tiny metal particles from years of keys going in and out. Moisture can add corrosion, and the film turns that buildup into something sticky. The key goes in, but the turn feels gritty or heavy.
Both causes can be present at once, and either one can get worse over time. A lock that is only a little stiff in the wet months often becomes stiff all year.
What you can check yourself
- Test it with the door openWhile the door is open, turn the key and work the bolt a few times. If it moves freely, the cause is probably door alignment. If it is still stiff, the cylinder is the likely cause.
- Look at the gap and the strike plateClose the door and look at how the latch and bolt line up with the holes in the frame. Rubbing marks or a tight fit on one side point to a door that has swelled or moved.
- Try your spare keyA worn or slightly bent key can feel stiff even in a healthy lock. If the spare turns more smoothly, the original key may just need replacing.
- Turn gently, never hardForcing a stiff key is how it snaps in the lock. If it will not turn with light, steady pressure, stop there.
- Leave oil and general-purpose spray aloneThey tend to gum up a cylinder and leave it worse than it was. A locksmith will use the right product for the job.
When to call a locksmith
Call when the lock is stiff both with the door open and shut, when the key feels rough or gritty, or when the stiffness comes back every damp spell. Call too if the key will not turn at all. If it ever leaves you locked out, the locksmith will ask for identification and proof that you are entitled to enter the home before opening anything, such as a driver's licence with the address, a lease or a utility bill. To arrange a visit, call (866) 690-5848.
One Call Locksmiths is a referral and scheduling service. We arrange the visit and an independent locksmith does the work. The estimate is free: the locksmith looks at the lock, gives you the price, and work starts only once you agree to it. If you want to know about licensing, it varies by state, with some states licensing locksmiths, others leaving it to cities or counties, and some not regulating the trade. Check with your own state or city.
What the locksmith will do
- Find where the stiffness comes fromThe locksmith separates the lock from the door and the frame as the cause, so you only pay for the fix that matches the problem.
- Clean, lubricate and re-pin or replace the cylinderIf the cylinder is the cause, it is cleaned and properly lubricated. If it is worn or corroded, it is re-pinned or replaced so the key turns smoothly again.
- Adjust the strike plate and hingesWhere the door has moved, the strike plate and hinges are adjusted so the latch and bolt meet the frame cleanly.
- Test the latch and deadboltThe latch and deadbolt are tested open and closed several times before the job is finished.
Related questions
- Will the lock free up when the weather dries out?
- If a swollen door is the cause, it often eases in dry weather. That only hides the underlying problem, and a lock with grit or corrosion in it usually keeps getting stiffer.
- Does a stiff lock mean I need a new lock?
- Not necessarily. Many stiff locks need only cleaning, an adjustment to the strike plate or hinges, or a new cylinder. The locksmith will tell you which before you agree to the price.
- Can a stiff key snap?
- Yes, forcing a stiff key is a common way for it to break. If it will not turn with light pressure, stop and arrange a locksmith visit instead.
- Is it the lock or the door?
- Try the lock with the door open. Smooth action points to the door and frame, and stiffness points to the cylinder. A locksmith can check both in one visit.
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