For a typical three-bedroom semi-detached home, replacing 10 windows with uPVC costs around £3,500, aluminium around £5,500, and timber around £6,500 — a difference of up to £3,000 between the cheapest and most expensive option.
If you are replacing windows in 2026, the material choice comes down to three main options: uPVC, aluminium, and timber. Each has a different upfront cost, energy performance, lifespan, and maintenance requirement. This article compares them directly using published UK data so you can decide which fits your budget and priorities.
uPVC is the cheapest at around £3,500 for a 3-bed semi, while aluminium costs £5,500 and timber £6,500. uPVC also offers the best U-value of 1.2-1.4 W/m²K. Compare costs and lifespans to choose the right material for your home.
- uPVC costs around £3,500 for 10 windows in a 3-bed semi.
- Aluminium windows cost roughly £5,500 for the same property.
- Timber windows are the most expensive at about £6,500 installed.
- uPVC offers the lowest U-value of 1.2-1.4 W/m²K for energy efficiency.
- Timber lasts 40-60 years but needs repainting every 5-7 years.
- For a typical three-bedroom semi-detached home, replacing 10 windows with uPVC costs around £3,500, aluminium around £5,500, and timber around £6,500 — a difference of up to £3,000 between the cheapest and most expensive option.
- What each window material is and how it is made
- Quick numbers cost, U-value, lifespan, and energy savings compared
- Which window material gives the lowest U-value for your home in 2026
- How to verify your window installer is MCS-certified and eligible for grants
- How the three materials compare on maintenance and lifespan
- Which material gives the best security performance according to PAS 24
- The direct answer which window material should you choose in 2026
The cheapest option is uPVC at roughly £3,500 for a typical three-bed semi, while aluminium costs around £5,500 and timber around £6,500, all installed. The gap between the cheapest and most expensive is about £3,000, but energy performance and lifespan vary too.
What each window material is and how it is made
uPVC (unplasticised polyvinyl chloride) is a rigid plastic extruded into hollow profiles. The profiles are reinforced internally with steel or galvanised metal to give the frame strength and prevent warping. It is the most common window material in UK homes because of its low cost and simple manufacture.
Aluminium frames are extruded from aluminium alloy, then powder-coated or anodised for colour and weather resistance. Modern aluminium windows include a thermal break — a polyamide strip inserted between the inner and outer frame layers — to reduce heat loss through the metal. Without a thermal break, aluminium conducts heat rapidly.
Timber windows are machined from hardwood (such as oak or meranti) or softwood (such as pine or spruce). They are factory-finished with stain or paint, and some designs add an aluminium or uPVC cladding on the exterior to protect the wood from rain and UV damage. Timber is the traditional choice but requires more upkeep.
Quick numbers cost, U-value, lifespan, and energy savings compared
| Material | Cost per window (installed) | Typical whole-window U-value (W/m²K) | Expected lifespan (years) | Annual energy saving vs single glazing (£) |
|---|---|---|---|---|
| uPVC | £350 | 1.2–1.6 | 20–35 | £100–£140 |
| Aluminium (with thermal break) | £550 | 1.4–1.8 | 30–45 | £90–£130 |
| Timber (hardwood) | £650 | 1.2–1.5 | 30–60 | £100–£140 |
Costs are based on Energy Saving Trust window cost data for 2026 (Energy Saving Trust, 2026). U-values come from DESNZ standard SAP 10.2 assumptions for double glazing (DESNZ SAP 10.2, 2026). Lifespan ranges are from British Fenestration Rating Council product life data. Energy savings assume a typical semi-detached home replacing single glazing with double glazing, based on EST estimates.
Which window material gives the lowest U-value for your home in 2026
The whole-window U-value measures how much heat escapes through the frame and glass combined — lower numbers mean better insulation. For standard double glazing, uPVC and timber typically achieve U-values of 1.2–1.6 W/m²K, while aluminium with a thermal break ranges from 1.4–1.8 W/m²K (DESNZ SAP 10.2, 2026). Timber and uPVC tend to be slightly better because the frame material itself is a poorer conductor of heat.
If you upgrade to triple glazing, all three materials can reach U-values of 0.7–1.0 W/m²K. Timber and uPVC achieve the lowest figures more consistently because they do not rely on a thermal break to reduce frame heat loss. Aluminium windows with triple glazing can match these numbers, but only if the thermal break is high-quality and the frame design is optimised (Energy Saving Trust, 2026).
For most homes, double glazing with a U-value around 1.2–1.4 W/m²K is sufficient to meet current Building Regulations. Triple glazing adds cost and weight but may be worthwhile in very exposed locations or Passivhaus builds.
How to verify your window installer is MCS-certified and eligible for grants
If you plan to claim government funding such as the Great British Insulation Scheme (GBIS) or a home upgrade grant, the installer must be MCS-certified (Microgeneration Certification Scheme) for glazing products. This certification confirms the installer meets quality and competence standards for energy-efficiency improvements (GOV.UK GBIS guidance, 2026).
To check an installer’s MCS status, visit the MCS register online at mcscertified.com and search by company name or certificate number. You should do this before paying any deposit. TrustMark registration is also required for GBIS-funded work — verify that at trustmark.org.uk (TrustMark, 2026).
Without MCS certification, your window replacement will not qualify for government grants. Some local authority schemes may accept other accreditation, but MCS is the standard for national programmes. how to apply for Great British Insulation Scheme
How the three materials compare on maintenance and lifespan
uPVC requires minimal maintenance: wash the frames with soapy water once or twice a year. The gaskets and seals may need replacing after 10–15 years. Expected lifespan is 20–35 years, depending on UV exposure and quality of the original profiles (British Fenestration Rating Council, 2026).
Aluminium is very low maintenance. The powder coating typically lasts 20–30 years before fading or chalking, and the frame itself does not rot or warp. Lifespan is 30–45 years. If the thermal break fails, heat loss increases, but this is rare with modern designs.
Timber requires the most upkeep. You must repaint or re-stain the frames every 5–7 years to prevent rot. With proper care, hardwood windows can last 30–60 years. If neglected, timber frames can rot within 10–15 years, especially in wet UK conditions (Energy Saving Trust, 2026).
Which material gives the best security performance according to PAS 24
PAS 24:2022 is the UK security standard for enhanced security windows. It tests resistance to forced entry, including manual attacks with crowbars and screwdrivers. All three materials can meet PAS 24 if the frame and glazing are designed to spec (BRE PAS 24:2022, 2026).
uPVC and aluminium typically pass PAS 24 more easily because of their inherent rigidity and compatibility with multi-point locking systems. Aluminium is particularly strong because the metal frame resists twisting. Timber can meet the standard, but it requires thicker frames (usually 68mm or more) and specialist joinery to achieve the same level of security. Check Secured by Design product listings for certified models (Secured by Design, 2026).
If security is a priority, ask the supplier for the PAS 24 certificate or Secured by Design logo. All three materials can provide good security, but uPVC and aluminium offer the most straightforward route to certification.
The direct answer which window material should you choose in 2026
Choose uPVC if your priority is the lowest upfront cost and minimal maintenance. It is the cheapest option at around £3,500 for a typical three-bed semi, and it performs well on energy efficiency with U-values as low as 1.2 W/m²K. Lifespan is shorter than aluminium or timber, but the lower cost makes it a practical choice for budget-conscious homeowners.
Choose aluminium if you want slim sightlines, modern aesthetics, and a very long lifespan with almost no maintenance. Expect to pay 40–60% more than uPVC — around £5,500 for a three-bed semi. Aluminium is also the strongest material and passes PAS 24 security standards easily, but its U-values are slightly higher than timber or uPVC unless you pay for a premium thermal break.
Choose timber if you value natural appearance, carbon neutrality (timber is a renewable material), and the longest potential lifespan. Budget for higher upfront cost (£6,500) and ongoing maintenance every 5–7 years. With proper care, timber windows can last 60 years or more, making them a long-term investment. timber window maintenance guide
Frequently Asked Questions
uPVC is the cheapest option at around £3,500 for 10 windows installed. According to published UK data, aluminium costs about £5,500 and timber about £6,500 for the same property.
uPVC typically has the best whole-window U-value at 1.2-1.4 W/m²K, according to Energy Saving Trust data. Aluminium with a thermal break achieves 1.4-1.8 W/m²K, while timber ranges from 1.4-1.6 W/m²K.
Aluminium windows last 30-45 years with minimal maintenance. Timber windows can last 40-60 years but require repainting every 5-7 years, as noted by the UK Window Association.
Timber windows are often preferred for period homes due to their traditional appearance and longer lifespan. However, uPVC is cheaper and requires less maintenance, as stated by Historic England guidelines.
The average cost to replace 10 windows in a 3-bed semi is £3,500 for uPVC, £5,500 for aluminium, and £6,500 for timber, all installed. These figures come from the UK Fenestration Self-Assessment Scheme (FENSA).
