Repair a window lock.

A broken lock isn't just a security risk; it can also invalidate your home insurance policy if a break-in occurs. Whether you have modern uPVC casement windows or traditional timber sashes, keeping your locking mechanisms in top condition is essential for safety and energy efficiency.

What Does the Work Involve?

• Diagnostic Inspection: The tradesperson will identify if the fault lies with the handle, the internal gearbox, or the strike plates on the frame.
• Component Removal: Removing the window handle and the "Espagnolette" (the long metal strip) or shootbolt system from the side of the sash.
• Sourcing Parts: Identifying the correct backset and spindle length for replacement parts, which is critical for uPVC units.
• Mechanism Replacement: Fitting the new gearbox or locking strip and ensuring all moving parts are correctly seated.
• Alignment Adjustment: Adjusting the window hinges (friction stays) to ensure the locking points line up perfectly with the frame.
• Testing and Lubrication: Applying silicone-based lubricant to ensure a smooth operation and testing the key lock functionality.

Typical Costs

Prices are influenced heavily by the window material and the age of the locking system. Obsolete parts for older windows may require "universal" retro-fit kits, which can increase both the material cost and the labour time required for modifications.

How Long Does It Take?

• Simple Handle Replacement: 15–30 minutes.
• Standard uPVC Gearbox Swap: 45–90 minutes.
• Complex Shootbolt or Sash Window Repair: 2–3 hours.
• Multiple Window Service: 4–6 hours for a whole-house "tune-up."

DIY or Professional?

Changing a window handle is a straightforward DIY task that usually requires only a screwdriver. However, if the window is jammed shut or the internal mechanism has snapped, a professional is required to "dead-lock" the window open without damaging the frame.

Professional Tip: If your window is stuck, do not force the handle. You risk snapping the internal spindle or shattering the handle, which makes the eventual professional repair more difficult and expensive.

Working on windows above the ground floor also carries safety risks. A professional handyman or locksmith will have the tools to safely access and repair the unit from the inside where possible.

Choosing the Right Tradesperson

• Specialism: Look for a handyman with specific experience in "uPVC repairs" or a locksmith.
• Spares: Ask if they carry common ESPAG sizes and handles on their van to avoid a second call-out charge.
• Warranty: Ensure they offer at least a 12-month guarantee on the mechanical parts fitted.
• Questions to ask: "Is the replacement lock PAS 24 rated?", "Do you need to remove the glass to access the mechanism?", and "Is there a 'no-fix, no-fee' policy for the diagnostic?"

UK Regulations

• Building Regs Part B: Repairs must not compromise fire escape routes. Replacement locks on "egress" windows must be easy to operate in an emergency.
• Building Regs Part Q: Concerns security for new dwellings, but it is good practice to ensure replacement locks meet PAS 24 standards.
• Insurance Compliance: Most UK insurers require window locks to be key-operable to meet their minimum security criteria.

Common Problems

• Dropped Sashes: The window catches on the bottom frame, putting pressure on the lock. This usually requires hinge adjustment, not just a new lock.
• Seized Gearboxes: Caused by a lack of annual lubrication. The internal springs snap when the handle is forced.
• Misaligned Strike Plates: The lock works when the window is open but won't turn when closed. This indicates the frame has shifted.
• Incorrect Spindle Length: Using a spindle that is too short will cause the handle to spin freely without engaging the lock.

Frequently Asked Questions