How Much Does It Cost to Replace Windows in the UK?

Window replacement cost varies significantly by frame material and glazing specification — more than most people expect going in. This is a specialist, certification-gated trade (FENSA or an equivalent competent-person scheme in the UK), so this guide is informational, covering what to expect and check, not a service we install ourselves.

Typical UK window replacement costs

These are general, indicative supply-and-fit ranges per window — actual cost depends heavily on size, frame material, glazing type and how many you're replacing at once.

• uPVC, standard double glazing: roughly £400–£800 per window
• Timber (softwood), double glazing: roughly £700–£1,200 per window
• Timber (hardwood) or aluminium: roughly £900–£1,600 per window
• Triple glazing: typically adds 15–25% over an equivalent double-glazed window

See our companion guide on double glazing costs specifically for more detail on glazing type and its effect on price.

A worked example: replacing a whole house

For a typical semi-detached house with around 10 standard-sized windows, replacing the full set in uPVC with standard double glazing typically lands in the £4,500–£7,500 region, benefiting from the shared cost of a single site visit and scaffolding/access setup versus pricing each window as a separate job. The same house in timber frames would typically be £8,000–£12,500, and in aluminium or hardwood timber, £10,000–£15,000+ — before accounting for any non-standard windows (bay windows, large picture windows) which push individual units above these per-window averages.

What affects the price beyond the headline figure

• Frame material — the single biggest cost driver, as shown above.
• Window size and shape — bay windows, arched windows and non-standard shapes cost more than a straightforward rectangular opening.
• Number of windows done together — doing a whole house at once is usually more cost-effective per window than one-off replacements, due to shared site setup.
• Access — upper-floor windows needing scaffolding or a cherry picker add real cost over ground-floor replacements.
• Removal and disposal — of the old windows and frames, worth confirming is included.
• Listed building or conservation area restrictions — can require specific materials or styles, sometimes at a premium over standard options.

Energy efficiency and U-values

Every window sold in the UK carries a U-value (a measure of heat loss — lower is better) or a Window Energy Rating from A++ to G. A modern double-glazed uPVC window typically achieves a U-value of around 1.4 W/m²K or better; older single glazing sits closer to 4.8–5.8 W/m²K, which is why replacing genuinely old single glazing shows the biggest real-world improvement in comfort and heating costs. When comparing quotes, ask for the specific U-value or energy rating of the product being quoted, not just a generic "energy efficient" claim.

What to check before choosing an installer

• FENSA or equivalent competent-person scheme registration — this is what allows work to be self-certified as compliant with building regulations, without a separate building control application.
• A genuine written guarantee on both the product and the installation, not just one or the other.
• Clear energy-efficiency ratings (a U-value or Window Energy Rating) for the specific product being quoted, not just a generic claim.
• What's included in the quote — removal and disposal of old windows, making good internally and externally, and any necessary building work around the opening.

A realistic timeline

A standard single window replacement typically takes under a day. A whole-house replacement of 10–15 windows is usually completed in 2–4 days, weather permitting for external work — genuinely quick compared to most other home improvements on this list, which is one reason it's often tackled as a standalone project rather than bundled with a larger renovation.

Planning and building regulations

Like-for-like window replacement rarely needs planning permission, though listed buildings and conservation areas often have specific restrictions on style and materials — always confirm before ordering. Building regulations compliance is required regardless, which is exactly what a FENSA-registered installer's self-certification covers.