Casement Window Cost Guide UK (2026)

Approximately 70% of residential homes in the UK utilise casement windows as their primary glazing solution. This dominance is due to their simple mechanical operation—hinging at the side and opening outwards—which allows for maximum ventilation and unobstructed views. However, for a homeowner in 2026, the price gap between a basic uPVC unit and a high-performance timber frame can exceed £2,000 per window.

What Exactly is a Casement Window?

A casement window is defined by its hinge, which is located on one of the vertical sides of the frame. When opened, the sash swings outward, typically pushed by a handle or a stay bar.

In the UK market, you will encounter two primary styles:

1. Standard Casement: The sash sits proud of the frame, creating a visible step. These are the most common and generally the most affordable.
2. Flush Casement: The sash sits flush with the frame, mirroring the appearance of traditional timber windows. These are highly prized in conservation areas and heritage homes for their clean, flat aesthetic.

Casement Window Costs by Material

The material choice is the single most significant driver of cost. Based on current market data from the WindowCost Pricing Matrix, we can see a clear hierarchy in pricing for a standard 1200x1000mm opening.

uPVC Casement Windows

uPVC remains the go-to for the majority of UK replacements due to its thermal efficiency and low maintenance.

• Typical Price Range: £350 – £800 per window (installed).
• Regional Variance: In Manchester or Leeds, a standard double-glazed uPVC casement can be found for between £540 and £990. In London, the same unit often jumps to £780 – £1,430 due to higher labour indices.
• Pros: Highly energy-efficient, budget-friendly, and requires no painting.
• Cons: Cannot be repaired if the frame cracks; some lower-end profiles can yellow over time (see our uPVC lifespan guide).

Aluminium Casement Windows

Aluminium has seen a surge in popularity for modern renovations, particularly where “slim sightlines” are desired.

• Typical Price Range: £1,100 – £2,200 per window.
• Performance: Aluminium is inherently more conductive than uPVC, so modern units must be “thermally broken” to prevent cold bridging.
• Pros: Exceptional strength-to-weight ratio, allows for larger glass areas, and offers a contemporary look.
• Cons: Higher initial capital outlay compared to uPVC. For a full breakdown of the trade-offs, see aluminium windows pros and cons.

Timber Casement Windows

Timber is the gold standard for heritage properties and those seeking a premium, organic feel.

• Typical Price Range: £1,400 – £3,000+ per window.
• High-End Options: Accoya and other engineered timbers reduce the risk of warping and extension of the paint cycle.
• Pros: Timeless aesthetic, biodegradable, and can be repaired through traditional joinery.
• Cons: Significant maintenance requirements. Most timber frames require a full repaint every 8-10 years (detailed in timber windows maintenance).

Factors That Inflate the Price

Beyond the material, several variables can push a quote toward the higher end of the spectrum.

1. Glazing Specifications

While double glazing is the baseline, upgrading to triple glazing adds roughly 20-30% to the cost of the glass unit. In colder climates or for ground-floor rooms, triple glazing provides a noticeable increase in acoustic insulation. We recommend checking the double vs triple glazing comparison to see if the investment matches your thermal needs.

2. Energy Coatings (Low-E)

Most modern UK casements now include Low-Emissivity (Low-E) glass. This is a microscopic metallic layer that reflects heat back into the room. Using a Low-E coating can reduce the U-value of the window, helping you meet Part L building regulations.

3. Hardware and Security

Standard handles are cheap, but upgrading to multi-point locking systems or high-security hinges (PAS 24 compliant) will add cost. Many premium providers like Anglian and Everest offer a range of styles from basic casements to high-end flush options, depending on the security and aesthetic requirements of the property.

Installation and Certification

In the UK, window installation must comply with Building Regulations. There are two primary routes to achieve this:

1. Competent Person Schemes: If your installer is registered with FENSA or Certass, they can self-certify the installation. This is the most common route.
2. Building Control: If the installer is not registered, you must notify your local authority’s Building Control department and pay for an inspection.

Failure to obtain a certificate can cause significant delays when selling a home, as solicitors will require proof that the windows meet current thermal and safety standards.

Cost Summary Table: 1200x1000mm Standard Casement

Material	Average Low (Regional)	Average High (London)	Lifespan	Maintenance
uPVC	£540	£1,430	20-30 Years	Low
Aluminium	£990	£2,860	40+ Years	Low
Timber	£1,530	£4,420	60+ Years	High

Final Decision Matrix: Which should you choose?

• Budget-focused? Go for uPVC. It provides the fastest return on investment through energy savings.
• Modern aesthetic? Choose Aluminium. The slim frames provide a seamless transition between indoors and outdoors.
• Period property? Opt for Timber. It is often the only material permitted by local planning authorities in conservation areas.

When requesting quotes, always ask for a “fully installed” price. This should include the removal and disposal of old frames, internal making-good (plastering/trimming), and the provision of a FENSA/Certass certificate.

Regional Price Variations

Window installation costs across the UK vary by as much as 40% between the cheapest and most expensive regions. The primary driver is labour cost, which reflects local wage rates and the cost of doing business.

• London and South East: Expect to pay 15–25% above national averages. A uPVC casement that costs £600 in Leeds may cost £800 in Croydon.
• South West and Cotswolds: Pricing is moderate but lead times can be longer due to the high volume of period properties requiring specialist joinery rather than standard casements.
• Midlands and North of England: The most competitive pricing in the UK. High volumes of 1930s and post-war housing with standard window sizes make supply and installation efficient.
• Wales and Scotland: Labour rates are lower, but some rural areas carry a travel surcharge. Overall, prices sit at or slightly below national averages.

Common Mistakes When Buying Casement Windows

1. Choosing on price alone: The cheapest quote often means the cheapest profile. A £300 uPVC casement from an unknown manufacturer may have a thinner wall profile, fewer internal chambers, and a shorter guarantee than a £500 unit from a brand like Liniar or Profile 22.
2. Ignoring the glass specification: Two identical-looking windows can have very different U-values depending on the glass. Always confirm the Window Energy Rating (WER)—A++ is the current best, and anything below B is not worth installing.
3. Forgetting about trickle vents: Building Regulations Part F requires background ventilation in habitable rooms. If your existing windows have trickle vents, your new ones must too (or you must provide alternative ventilation).
4. Not checking the guarantee: Some guarantees cover only the frame, not the glass or the hardware. The seal between the double-glazing panes is the component most likely to fail—ensure it is covered for at least 10 years.
5. Assuming all installers are equal: A FENSA or Certass registration proves competency, but the quality of the internal finishing (plasterwork, trim, and sealant) varies enormously. Ask to see previous installations or check online reviews before committing.

Frequently Asked Questions

How long do uPVC casement windows last? Quality uPVC windows typically last 20–30 years. The frames themselves are durable, but the double-glazing seals may fail after 15–20 years, causing condensation between the panes. At this point, the glass units can be replaced without changing the frames.

Do I need planning permission to replace my windows? In most cases, no—replacement windows fall under Permitted Development rights, provided the new windows are similar in appearance to the existing ones. However, if your property is listed or in a conservation area with an Article 4 Direction, you will need Listed Building Consent or planning permission.

Are flush casement windows worth the extra cost? Flush casements cost 15–30% more than standard casements but offer a cleaner aesthetic that is particularly valued in period properties and conservation areas. They are also slightly more airtight because the flush fit eliminates the external step where draughts can penetrate.