Cost of replacing window locks

Window lock replacement becomes necessary after a break-in attempt, hardware failure, key loss, or when an ageing mechanism no longer feels secure. Because lock types vary considerably across uPVC, aluminium, timber sash, and timber casement windows, so do parts costs and labour requirements. Understanding what drives the price helps you evaluate quotes accurately and avoid overpaying for a straightforward hardware swap — or underpaying for one that leaves your window insecure.

Key points

• uPVC espagnolette (multi-point) locking mechanisms — the most common type in UK homes built or re-glazed after the mid-1990s — typically cost £30–80 for the gearbox or handle mechanism alone; labour adds approximately £50–100 per window (Indicative UK costs, last reviewed 2026-05-19).
• Cockspur handles and casement stays are simpler hardware; parts cost roughly £8–25 and most competent DIYers can replace them in under 30 minutes with the correct like-for-like part.
• Home insurers may require window locks to meet BS 7950 (Enhanced Security Performance for Windows) or equivalent Secured by Design standards — check your policy before specifying replacement hardware.
• A locksmith is not always the right trade for window locks; window hardware specialists and the original installer are often better placed for uPVC multi-point mechanisms that require alignment adjustment.
• Sash window locks (Brighton fasteners, dual screws, sash stops) are usually low-cost parts at £5–20 each, but correct fitting into older timber frames may require carpentry experience.

Window lock types and typical replacement costs

The table below gives indicative UK cost ranges for common residential window lock types. Prices vary by region, specification, and installer. Always obtain at least two quotes.

Indicative UK costs, last reviewed 2026-05-19. Quotes vary by region, lock specification, and number of windows.

What affects the cost of window lock replacement?

Lock type and complexity

A simple cockspur handle replacement costs a few pounds in parts and takes minutes. A full uPVC multi-point locking mechanism may require careful removal and realignment of the keeps (the parts fixed to the frame surround), precise spindle measurement, and adjustment of the compression against the frame seal. This takes considerably longer and the mechanism itself is more expensive. If the existing keeps are worn or out of position, additional adjustment time adds to the bill.

Like-for-like versus security upgrade

Replacing a failed lock with an identical model is the most straightforward and cost-effective route if compatible parts are available. Upgrading to a higher-security lock — for example, fitting a BS 7950-compliant handle on a uPVC window that previously had a basic handle — may require minor frame modifications and costs more in both parts and labour.

Access and location

Ground-floor windows are the most straightforward to work on. Windows above first-floor level may require a ladder, hop-up, or access tower, which can add to the cost. Internal-only access to upper-floor windows reduces this but may complicate external adjustment.

Number of windows

Most tradespeople charge a call-out fee plus a per-window rate. Having all affected windows attended in one visit is considerably more cost-effective per lock than separate call-outs. If several locks across the property need attention, batch the work.

Age and profile of the window

Modern uPVC profiles from major manufacturers often use standard hardware dimensions (spindle length, PZ measurement, backset), making compatible parts easy to source from trade suppliers. Older profiles, discontinued product lines, or European brands may use proprietary dimensions that are harder to match, and sourcing the correct part may take longer and cost more.

DIY versus professional replacement

Replacing a simple casement handle or cockspur stay is within the ability of most competent DIYers, provided you measure the existing fitting accurately before purchasing a replacement. The key measurements are the spindle length, the backset (distance from the edge of the frame to the spindle centre), and where applicable the PZ measurement (distance between spindle centre and keyhole centre). Photograph the existing lock from both sides before removing it.

Multi-point locking mechanisms are more involved. A mechanism that is slightly misaligned may appear to lock but will not compress the frame seals evenly, compromising both security and weatherproofing. If you are uncertain, the labour cost for professional fitting is usually worth paying.

For aluminium windows, lock replacement typically requires knowledge of the specific profile system — such as Schüco, Kawneer, or SAPA — and is best handled by a specialist familiar with that manufacturer's hardware.

Quote comparison template

Before accepting any quote for window lock replacement, ask:

• What is the exact lock or mechanism being fitted? Request the brand, model, and any security certification (e.g., BS 7950, Secured by Design).
• Is the quoted part like-for-like or an upgrade? Confirm whether it meets your home insurer's requirements.
• Is the call-out fee separate from the per-window rate, or is everything included?
• Will the lock be tested after fitting to confirm it engages fully on all locking points and that the frame compresses evenly?
• Is VAT included in the quoted price?
• What happens if additional parts are needed once the mechanism is opened up? Is there an agreed day-rate or fixed price for unforeseen complications?
• Is there a guarantee on parts and labour, and for how long?
• Will you provide a written receipt confirming the work done and the security standard of the hardware fitted?

When to get professional help

Contact a window hardware specialist or your original window installer if:

• The frame is damaged around the lock keep — new hardware will not perform correctly until the frame is sound.
• You cannot identify the window profile or the existing mechanism type from photographs or measurements.
• The window does not close flush, which may indicate frame distortion rather than a failed lock — forcing a new lock will not fix the underlying problem.
• You need to document the upgrade for a change to your home insurance policy; a professional can provide a receipt confirming the security standard fitted.
• The window is aluminium with a proprietary profile system.

How Housey can help

Finding a reliable specialist to assess and replace window locks is straightforward with Housey. Our window and door installers can identify compatible hardware, confirm security ratings against insurer requirements, and provide a receipt for your records. Compare quotes from vetted local professionals on Housey.

Frequently asked questions

How much does it cost to replace a uPVC window lock?

For a standard uPVC espagnolette (multi-point) mechanism, expect to pay roughly £80–180 in total for parts and labour, depending on the mechanism type and your location. Simple handle-only replacements on uPVC casements are often £40–80 all-in. These are indicative UK costs, last reviewed 2026-05-19; always obtain at least two quotes.

Can I replace window locks myself?

Simple casement handles and cockspur stays are usually straightforward to replace if you match the existing part's dimensions accurately. Multi-point locking mechanisms and aluminium profile locks are more complex; misalignment can leave the window insecure. Professional fitting is advisable for anything beyond a basic handle swap.

Do my window locks need to meet a specific standard for home insurance?

Many UK home insurers require window locks to meet BS 7950 (Enhanced Security for Windows) or a comparable standard such as Secured by Design certification. Check your policy wording before purchasing replacement hardware — fitting non-compliant locks could invalidate a claim related to a window break-in.

How do I find the right replacement part for my uPVC window lock?

Note the PZ measurement (distance between handle spindle and keyhole centre, where applicable), the spindle length, and the backset. Photograph the existing mechanism from both sides. Most window hardware suppliers can match parts from these measurements. The original window manufacturer or installer is also a useful starting point.

Sources and further reading

• Secured by Design: police crime prevention initiatives — Secured by Design
• BSI Group: BS 7950 enhanced security for casement and tilt/turn windows — BSI Group
• Which? home security: window and door locks — Which?
• Citizens Advice: home security guidance — Citizens Advice