If you’re replacing windows in a UK home in 2026, the first decision that actually matters is material — uPVC or aluminium. Most homeowners default to uPVC because it’s cheaper and familiar; many end up wishing they’d gone aluminium for the look. This guide breaks down the honest trade-offs with 2026 numbers.

The short answer

• Choose uPVC if: budget is tight, property is a standard UK semi/terrace, maximum thermal efficiency per pound matters, white or anthracite-grey is fine
• Choose aluminium if: you want slim frames with more glass, property is modern/contemporary-styled, colour matching architecture matters, long-term cost (30-year horizon) matters more than upfront

Cost comparison (typical UK 2026 installed prices)

Property	Windows	uPVC total	Aluminium total	Premium
Flat / small terrace	3-4	£1,800 – £3,200	£2,600 – £4,500	~40%
2-bed terrace	6-8	£3,600 – £6,400	£5,200 – £9,000	~40%
3-bed semi	8-10	£4,500 – £8,500	£6,500 – £12,000	~40%
4-bed detached	10-14	£6,500 – £13,000	£9,500 – £19,000	~45%

Aluminium is consistently 40-45% more expensive than uPVC for comparable spec. The rest of this guide is about whether the premium is worth it for your specific property.

Performance — where each wins

Factor	uPVC	Aluminium (thermally broken)
Typical u-value	1.2 – 1.4 W/m²K	1.3 – 1.6 W/m²K
Frame thickness	70-90mm	40-60mm (much slimmer)
Glass-to-frame ratio	Lower (more frame visible)	Higher (more glass, better light)
Lifespan	20-25 years typical	30-40 years typical
Repaint options	Cannot be painted later	Can be re-sprayed professionally
Colour range	Factory foils — ~15 colours	Any RAL colour, dual-colour available
Fire performance	PVC softens at high temperatures	Non-combustible (matters for high-rise flats)
Recyclability	Partially recyclable	Fully recyclable, no loss of quality

Thermal performance — the honest answer

uPVC has a slight edge on thermal efficiency. Modern aluminium windows use a thermal break (polyamide strip inside the frame) to compete, but uPVC still wins marginally. In practice, the difference is small — roughly £15-£30 per year on a typical UK semi’s gas bill. Over 25 years that’s £375-£750. Doesn’t justify the £2,500+ aluminium premium on thermal grounds alone. If energy efficiency is your primary driver, stick with uPVC and put the saved budget into triple glazing.

Sightlines — why some homeowners pay the premium

The real argument for aluminium is visual. Aluminium frames are 30-50% thinner than uPVC because aluminium is structurally stronger. The result: more glass, less frame, more light, cleaner modern look. On a large bay window or a picture window, the difference is dramatic. On a standard upstairs bedroom window, it’s marginal.

When aluminium makes obvious sense

• Modern or contemporary-styled properties
• Large picture windows or full-height glazing where sightlines matter
• Coastal properties — handles salt air better over 20+ years
• High-rise flats where fire performance matters
• Colour-match critical — historic properties with dark frames, bespoke architectural schemes

When uPVC is the obvious answer

• Standard Victorian / Edwardian / 1930s-1970s UK semi or terrace — uPVC is the default
• Budget-driven whole-house replacement
• Rental properties
• When thermal performance matters more than sightlines

Frequently asked questions

Does aluminium condense more than uPVC?

Not in a properly-specified modern window. Cheap aluminium (without a thermal break) condenses badly. Any 2026 aluminium window from a FENSA-registered installer will have a full thermal break. Performance is then comparable to uPVC. The old reputation for “cold aluminium” is pre-2010 technology.

Can I mix aluminium and uPVC on the same property?

Yes — it’s common. Aluminium on front-elevation feature windows (bay windows, picture windows) + uPVC elsewhere gets you the aluminium aesthetic where it matters for 30-40% less cost than a full-aluminium house.

Does aluminium add more to resale value?

In modern properties (post-1990), yes — aluminium matches buyer expectations for the aesthetic. In period properties (pre-1950), difference is negligible — buyers expect timber or mock-timber-style uPVC. Don’t assume aluminium is a universal resale upgrade.

Are aluminium windows noisier than uPVC?

Marginally — thinner frames transmit slightly more external sound. Difference is small and resolvable by choosing acoustic-laminated glass (£200-£400 upgrade per window). On a busy road, specify acoustic glass regardless of frame material.

The 3-question test

1. Is your property modern/contemporary or period? Modern → aluminium leans right. Period → uPVC or timber
2. Is budget a constraint? If yes, uPVC. The 40% premium is real
3. How long will you stay? 15+ years and aluminium’s longevity adds up. Under 10 years and resale value is doing the work (depends on Q1)

Get four quotes in both materials

Any FENSA-registered installer quotes both. Findfitter matches you with 4 FENSA-registered installers — ask each for separate aluminium and uPVC quotes to see the real delta for your specific property.

Sources

• British Fenestration Rating Council (BFRC) — u-value testing methodology
• FENSA installer register
• UK aluminium systems market data 2024-2025