uPVC and aluminium are the two materials most UK homeowners actually choose between in 2026 (timber sits apart as a heritage option, weighed up in our uPVC versus timber and aluminium versus timber comparisons). The short version: uPVC is the value pick at £400 to £1,000 per window fitted, while aluminium runs £540 to £1,350, roughly 30 to 40% more, and buys you slimmer frames and a longer life, which is what makes the dearer window the cheaper one on a long enough view. Below we compare them across five dimensions that matter, then give a verdict. If you are unsure which frame suits your home, our material classifier weighs your priorities, and once you know which way you are leaning, the uPVC window calculator and the aluminium window calculator will price your own house.
The headline comparison
Before the detail, here is the side-by-side picture. The figures are fitted, per-window ranges for a standard casement, the style most homes use.
| Dimension | uPVC | Aluminium |
|---|---|---|
| Cost per window (fitted) | £400–£1,000 | £540–£1,350 |
| Price vs uPVC | Baseline | Around +30 to 40% |
| Lifespan | 20 to 25 years | 30 to 40 years |
| Frame sightlines | Chunkier | Slim, more glass |
| Maintenance | None | None |
| Thermal performance | 1.0 to 1.4 W/m²K | 1.0 to 1.4 W/m²K |
Source: DGCC 2026 dataset (Checkatrade). Aluminium uplift around 30 to 40% vs uPVC.
Cost
Cost is the clearest difference. A fitted uPVC casement sits in the £400 to £1,000 band, while the same window in aluminium is £540 to £1,350, an uplift of around 30 to 40%. On a ten-window house that gap can mean several thousand pounds, so aluminium has to earn its premium on looks or longevity rather than performance alone. uPVC remains the entry point to A-rated glazing. These figures are cross-checked against Checkatrade.
Best Buy uPVC for cost. Nothing else gets you A-rated windows for less.
Looks and sightlines
This is where aluminium repays its premium. Because the metal is far stronger than plastic, the frames can be much slimmer while holding the same pane of glass. The result is more glass, more daylight and the crisp, minimal sightlines that suit modern extensions, large openings and bi-fold doors. uPVC frames are necessarily chunkier, which looks perfectly fine on a typical semi but can dominate a big picture window.
Worth it Aluminium for looks, especially on large or feature windows.
Lifespan
Aluminium lasts longer: around 30 to 40 years against uPVC's 20 to 25 years. Neither needs painting or real upkeep. In practice the sealed glass unit (15 to 20 years before any misting) often ages out before either frame does, so the longer aluminium life only really counts if you plan to stay put for decades. For more on how the frame and the glass age separately, see our guide to how long double glazing lasts.
Worth it Aluminium edges it on raw lifespan.
Thermal performance
Plastic conducts less heat than metal, so on raw insulation uPVC has a small natural advantage in the window frame itself. Modern aluminium closes nearly all of it with a polyamide thermal break running through the frame, which is why the energy efficiency gap between uPVC and aluminium windows is far narrower than the materials suggest. In 2026 both materials comfortably reach the A-rated standard of 1.0 to 1.4 W/m²K that Part L of the Building Regulations requires for replacement windows, so for most homes thermal performance is effectively a draw. The glass spec matters more here than the frame, and because uPVC and A-rated glazing are the kind of shorthand a double glazing glossary needs to unpack, our Double Glazing Glossary defines both in a line.
It depends A draw in practice; uPVC has a slight edge on paper.
Maintenance
Both are genuinely fit-and-forget, and on durability there is very little in it. uPVC needs nothing more than an occasional wipe, and powder-coated aluminium is just as undemanding, holding its colour for decades. Neither rots and neither needs painting, and while bare aluminium can corrode, a powder-coated frame will not rust in normal UK conditions. If you want the look of wood without the upkeep, both materials offer a woodgrain foil finish rather than the real thing. This is the one dimension where the two materials are simply level, and it is a big reason both have pushed timber to a niche.
Best Buy Tie. Both are essentially maintenance-free.
Nine times out of ten uPVC goes in and the owner never thinks about it again. Aluminium is worth the money on big openings and modern extensions, where those slim frames genuinely change how the room feels. Do not pay the aluminium premium on a back bedroom nobody looks at.
Double Glazing Cost Calculator Team
The disadvantages of uPVC windows
The frames are the thickest of any material, so for the same hole in the wall a uPVC window gives you less glass and more plastic than aluminium does — the reason it rarely suits a contemporary extension where the point is the view. It is the least strong of the three materials, so wide spans need internal steel reinforcement, and there is a practical ceiling on how large a single uPVC pane can go before the design has to break it into sections. White is the standard; woodgrain and coloured foils cost more and, on a south-facing elevation, older foils can fade over a couple of decades. Life expectancy is the shortest of the three at 20 to 25 years against aluminium's 30 to 40. And a damaged uPVC frame is generally replaced rather than repaired, because welded corners cannot be taken apart the way a mechanically jointed frame can.
The disadvantages of aluminium windows
Cost is the obvious one: roughly 30 to 40% more than uPVC for the same window, which on a full house is the difference between a £4,000 job and a £6,000 one. The less obvious one matters more, because it is the failure people do not see coming. Aluminium conducts heat readily, so an aluminium window only reaches modern efficiency figures when the frame is thermally broken — built in two halves separated by an insulating barrier. A cheap aluminium frame without that break will pull the whole-window U-value up even behind good glass, and in a cold snap the frame itself can run cold enough to attract condensation along the inside edge. Always ask whether the system is thermally broken and get the whole-window figure, not the centre-pane one; see how window U-values work for why those two numbers differ. Powder coating is tough but can chip, and a dented frame is a replacement rather than a repair.
The verdict
For most UK homes, uPVC is the Best Buy: it delivers A-rated performance at the lowest price with zero maintenance, and a 20 to 25 year life is plenty for the majority of owners. Choose aluminium where the look earns its keep, on large windows, bi-folds and contemporary extensions where slim sightlines transform the space and the longer life suits a long-term home. Frame material is only one of the double glazing comparisons behind a quote: if you are still weighing the glazing spec itself, our comparison of double versus triple glazing covers when the extra pane is worth paying for, and the full set of double glazing comparisons runs from gas fill to fitting method.
Frequently asked questions
Yes. A uPVC casement window costs roughly £400 to £1,000 fitted, while the same window in aluminium costs around £540 to £1,350, about 30 to 40% more. The gap comes from the metal frame, the thermal break inside it and the more precise fabrication aluminium needs.
They do. Aluminium frames last around 30 to 40 years, against 20 to 25 years for uPVC. Both are essentially maintenance-free. Over a very long ownership the longer aluminium life can offset some of the higher upfront cost, but for most owners the difference is academic.
uPVC is naturally a slightly better insulator because plastic conducts less heat than metal. Modern aluminium frames close most of the gap with a polyamide thermal break, and both materials reach the A-rated, Part L compliant standard of 1.0 to 1.4 W/m²K when fitted with good glass.
Yes, and this is aluminium's main selling point. The metal is stronger than plastic, so the frames can be much thinner while carrying the same glass. That means more glass, more light and cleaner sightlines, which suits large windows, bi-folds and modern extensions.