Install window locks.

Whether you are upgrading old timber sash fasteners, replacing snapped uPVC handles, or installing additional security bolts, professional installation ensures that the structural integrity of your window frames remains intact. This guide covers the essential costs, technical requirements, and regulatory standards for window lock installation in the UK.

What Does the Work Involve?

• Initial Assessment: The locksmith identifies the window material (uPVC, timber, or aluminium) and the specific lock type required (e.g., espagnolette, cockspur, or sash jammer).
• Measurement: Precise measurement of the "backset" and "spindle length" is crucial for uPVC windows to ensure the new handle interacts correctly with the internal gearbox.
• Removal: Careful removal of existing hardware to avoid stripping screw holes or cracking the window frame.
• Morticing and Drilling: For timber windows, the locksmith may need to cut new recesses (mortices) or drill pilot holes for bolts and fasteners.
• Fitting and Alignment: Installation of the new locking mechanism, ensuring the strike plate aligns perfectly with the bolt to prevent sticking.
• Operational Testing: Multiple tests to ensure the window seals tightly against draughts and that the locking cylinder operates smoothly without force.

Typical Costs

The cost of window lock installation varies depending on your location in the UK and the complexity of the locking mechanism. Standard uPVC handle replacements are generally the most affordable, while high-security sash window upgrades require more intensive labour.

Prices are inclusive of VAT where applicable. Significant discounts are usually available if you are having multiple windows upgraded during a single visit, as the call-out fee is spread across the whole job.

How Long Does It Take?

• Standard uPVC Handle Swap: 15–30 minutes per window.
• Multi-point Mechanism Replacement: 45–90 minutes depending on frame condition.
• Timber Sash Lock Installation: 1 hour per window (requires manual wood cutting).
• Full House Upgrade (3-bed semi): 4–6 hours to complete all ground and first-floor windows.

DIY or Professional?

While replacing a simple uPVC handle is a common DIY task, more complex issues should be left to a professional. If the internal gearbox has failed or the window is jammed shut, forced entry by an amateur can shatter the glass or warp the frame, leading to a much larger repair bill.

Professional installation is often a condition of your home insurance policy. Most UK insurers require "key-operable" locks on all ground-floor and accessible windows to provide full theft cover.

Locksmiths also have access to "trade-only" hardware that offers superior durability compared to the generic options found in high-street DIY stores. For timber windows, the precision required for morticing means a professional finish is essential for both security and aesthetics.

Choosing the Right Tradesperson

• Check Qualifications: Look for a locksmith who is a member of the Master Locksmiths Association (MLA), which requires Vetting, Inspections, and Qualifications.
• DBS Checked: Ensure the tradesperson has a current DBS (formerly CRB) check for your peace of mind.
• Specialism: Some locksmiths specialise in "auto" or "commercial" work; ensure yours has extensive experience with domestic window types, particularly uPVC if that is what you have.
• Warranty: A reputable professional should offer at least a 12-month guarantee on both the parts and their workmanship.

• "Are the locks you recommend compliant with BS 3621 or TS007 standards?"
• "Do you carry a wide range of spindles and backsets on your van, or will you need to order parts?"
• "Can you 'key-alike' all my window locks so one key fits every window in the house?"

UK Regulations

• Building Regulations Part Q: Applies to new dwellings, requiring windows to be manufactured to a design that has been shown by test to meet the security requirements of PAS 24.
• Fire Safety (Part B): While security is vital, locks on "means of escape" windows (typically in bedrooms) must be easily operable from the inside to allow for a quick exit in an emergency.
• Insurance Requirements: Most UK insurers specify that windows must have key-operated locks. Failure to engage these when the property is empty can void a claim.

Common Problems

• Dropped Sashes: If the window has dropped, the lock will not align with the strike plate. A locksmith must "toe and heel" the glass or adjust the hinges before fitting a new lock.
• Broken Gearboxes: If the handle spins freely without opening the window, the internal gearbox has likely shattered. This requires a specialist to bypass the lock and replace the internal strip.
• Wrong Spindle Length: Using a spindle that is too short won't engage the lock; one that is too long will prevent the handle from sitting flush, leaving it vulnerable to being pried off.
• Seized Mechanisms: In coastal areas, salt air can corrode internal window locks. Regular lubrication with a silicone-based spray is required to prevent total failure.

Frequently Asked Questions