Aluminium and uPVC dominate the UK window market between them, with timber a distant third. Both materials have evolved dramatically — modern uPVC is no longer the chunky 1990s plastic, and modern aluminium is no longer the cold, condensation-prone single-glazed material of the 1970s. Here's how they compare in 2026.
Cost
uPVC is significantly cheaper. Typical 3-bed semi re-glaze: £6,000-£10,000 in uPVC, £10,000-£18,000 in aluminium. Per-window installed cost: uPVC £450-£850, aluminium £700-£1,400. For comparable performance specifications.
Sightlines and aesthetics
Aluminium wins decisively. Aluminium profiles can be as slim as 50mm wide; uPVC profiles are typically 70-90mm wide. For modern architectural projects with large glazed areas, aluminium's slim sightlines give you significantly more glass and a more contemporary look.
Colour and finish
Aluminium can be powder-coated in any RAL colour with 25-year colour warranties — colours stay vibrant for decades. uPVC has improved enormously with foiled coloured finishes (chartwell green, anthracite grey, irish oak) but is generally limited to 30-40 standard colours and may show wear after 15-20 years on south-facing elevations.
Thermal performance
Modern uPVC achieves slightly better thermal performance than aluminium — typical whole-window U-values: uPVC 1.2-1.4 W/m²K vs aluminium 1.4-1.6 W/m²K (with thermal breaks). The difference is small and not material for most projects.
Strength and large openings
Aluminium wins. Aluminium can span openings up to 3m wide without intermediate supports; uPVC typically maxes out at 2-2.4m. For bifold doors, large picture windows, and structural openings, aluminium is the only viable choice.
Lifespan and maintenance
Both are essentially maintenance-free. Modern uPVC lasts 25-35 years; modern aluminium 45+ years. Powder-coated aluminium finishes carry 25-year colour warranties; modern foiled uPVC carries 10-year colour warranties.
Recommendation
Choose uPVC for: residential window replacement on standard-sized openings where appearance is secondary to cost. Choose aluminium for: contemporary extensions, large openings, bifold doors, architectural projects, and any application where slim sightlines and premium aesthetics matter. We supply both — call 0800 088 6341 for a comparison quote.
Need help with your glazing project? S&K Glazing offers free surveys and fixed-price quotes across the UK. Call 0800 088 6341, message us on WhatsApp at 07830 175306, or request a quote online.