uPVC expands in hot weather and contracts in cold weather, and the Master Locksmiths Association says being just 1mm or 2mm out of alignment can stop a door locking. The fix is usually a small adjustment to the keeps, rollers or hinges, not waiting for the weather to change.
A multipoint lock has several hooks, rollers or bolts that have to slide into keeps along the frame at the same moment. The MLA guide explains that uPVC, like wood and metal, expands and contracts, and that a door slightly out of alignment will struggle both to lock and to unlock. Each locking point is another place where the door can catch.
In cold or freezing weather, the MLA guide says the uPVC contracts, and shrinking of only 1mm or 2mm is enough to stop the door locking. In hot weather it says the uPVC expands, so the door becomes stiff and difficult to shut or open. Either way, the handle usually feels fine with the door open and stiff once it is closed.
It is tempting to wait for the weather to turn. The MLA guide advises against it, because the problem comes back as soon as the weather changes again. Forcing the handle in the meantime adds wear, and the same guide says poor alignment can make the gearbox or multipoint lock fail. It also says changes in the weather can make parts break, snap or shatter.
Many uPVC doors have adjustable keeps and rollers. ERA's fitting instructions say its keeps can be moved by loosening the screws and sliding the insert along slotted holes, and that its eccentric rollers can be turned up to a quarter turn either way. Small moves are usually all it takes. If the door has to be lifted to close, the hinges need setting, which is better left to a locksmith.
If the door will not lock in a cold snap or a heatwave, realigning it costs £110 on weekdays from 8am to 6pm, £140 on evenings and weekends, and £150 from 10pm to 8am, with travel and up to one hour on site included. You send the job through the form or the chat, and the price is fixed before we set off.
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Related questions
- Why does my uPVC door lock when I open it but not when I close it?
- How to fix a uPVC door that won't lock?
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