London · Q2 2026
uPVC vs Aluminium Windows
Aluminium isn't better. It's different.
Marketing pretends aluminium is the premium upgrade and uPVC is the budget compromise. Reality is more nuanced. After 6,000+ projects across Richmond, Twickenham, Kingston, Chiswick, Putney, Wimbledon, Hammersmith and Fulham, the pattern is clear: aluminium wins for slim sightlines, large spans, contemporary looks, Crittall replacement and Passivhaus thermal numbers. uPVC wins for cost, traditional casement and sash configurations, and a proven 30-year UK service history. Many London projects use both — uPVC at the front, aluminium at the rear extension.
The full comparison
Side-by-side on the metrics that matter for a London 2026 specification. uPVC numbers reflect modern multi-chamber systems (REHAU, Liniar, Eurocell heritage); aluminium numbers reflect Cortizo Cor 60/70/70 Industrial and Schüco AWS 70.HI / 75.SI+.
| Spec | uPVC | Aluminium |
|---|---|---|
| Fitted price (single casement) | £550–£1,800 | £900–£3,000+ |
| Minimum sightline | 70 mm | 45 mm |
| Typical sightline (mid-range) | 90–105 mm | 75–87 mm |
| Whole-window Uw (mid-range double) | 1.2 W/m²K | 1.4 W/m²K |
| Whole-window Uw (high-end triple) | 0.85 W/m²K | 0.79 W/m²K |
| Maximum unsupported span | ~2.4 m | ~5.0 m |
| Maximum sash height (casement) | ~2.0 m | ~2.5 m |
| Lifespan in service | 25–30 yr | 30–40 yr |
| Frame guarantee | 10 yr | 10–20 yr |
| Colour range | Solid + woodgrain foils | Full RAL palette + dual colour |
| Colour stability over 20 yr | Foils can fade in direct sun | Powder-coat extremely stable |
| Recyclable | Yes (now widely) | Yes (highest scrap value) |
| Best for | Casement, sash, bay/bow, budget | Slim, contemporary, Crittall, large spans |
Cost — fitted prices in London Q2 2026
Per-window installed prices including frame, double glazing, fitting, FENSA self-certification (Reg 40373), removal of old window and 10-year installation guarantee. Triple glazing adds 20–25%; obscure / patterned glass typically free; coloured aluminium powder-coat free up to standard RAL.
| Window | uPVC | Aluminium |
|---|---|---|
| Single casement (1.2 × 1.2 m) | £550–£900 | £950–£1,500 |
| 2-light casement (1.5 × 1.4 m) | £750–£1,200 | £1,400–£2,200 |
| 3-light casement (1.8 × 1.4 m) | £950–£1,500 | £1,700–£2,600 |
| Tilt-and-turn (1.2 × 1.5 m) | £900–£1,400 | £1,500–£2,500 |
| Sliding sash (1.0 × 1.8 m) | £1,100–£1,800 | Not common |
| Heritage flush sash (1.0 × 1.2 m) | £800–£1,300 | £1,400–£2,200 |
| Crittall-style steel-look (4-pane) | Not feasible | £2,200–£3,800 |
| Picture window (2.0 × 1.8 m fixed) | £1,200–£1,800 | £1,800–£2,800 |
| Bay window (3-bay, 3m wide) | £2,400–£3,800 | £4,200–£6,500 |
When uPVC wins
For these scenarios, uPVC is the right answer — and resisting the upsell to aluminium will save you 40–50% with no real downside. Honest installer-side advice.
| Standard semi-detached or terrace casement upgrade |
| Traditional sliding sash window replacement (uPVC heritage range now excellent) |
| Bay and bow window replacement on Edwardian and Victorian properties |
| Conservation-area front elevations where heritage uPVC is approved but aluminium isn't |
| Flush-sash heritage replacement where the look is the brief |
| Buy-to-let, HMO and short-hold investment properties (cost > longevity) |
| Whole-house replacement on a tight budget where every £1k matters |
| Window openings under 2.4m in any single dimension (no span advantage to aluminium) |
| French doors and standard patio doors where the slim sightline doesn't matter |
When aluminium wins
For these scenarios, aluminium is genuinely the only credible answer. uPVC physically can't replicate the slim sightline or carry the structural span.
| Crittall steel-frame replacement (Cortizo Cor 70 Industrial) |
| Slim contemporary sightlines under 70mm |
| Picture windows over 2m × 2m unsupported |
| Corner glazing — 90° structural corner without a corner mullion |
| Passivhaus or near-Passivhaus retrofit (Cortizo Cor 4700, Schüco AWS 90.SI+) |
| Slim sliding doors (Cortizo Vision, APX20 Plus, Schüco ASE — no uPVC equivalent) |
| Bifold doors at 4+ panes (uPVC bifolds get heavy and saggy fast) |
| Architect-spec contemporary new-builds where the brief specifies aluminium |
| Rear extensions with garden views — slim sightline = clean view |
| Properties expected to be held 30+ years (longer service life) |
| Bold or non-standard colours (anthracite, sage green, dual-tone) |
The mixed-property approach
A pattern we now fit on roughly 30% of London projects: uPVC at the front (heritage, conservation, cost-effective sash), aluminium at the rear (slim sightline, contemporary extension, large opening). Done right, the property reads as coherent because each material is in its correct context.
| Location | Material | Why |
|---|---|---|
| Front elevation (Victorian terrace) | uPVC heritage sash | Conservation-area approval, period accuracy, lower cost |
| Side bay window | uPVC casement | Matches front, no slim-sightline benefit |
| Rear extension (kitchen-diner) | Aluminium picture window | Large unsupported span, slim sightline, garden view |
| Rear extension door | Aluminium slim slider (Vision / APX20 Plus) | 20mm interlock, contemporary brief |
| First floor rear bedroom | Aluminium tilt-and-turn (Cor 70) | Slim, easy clean from inside, modern feel |
Frequently asked
Are aluminium windows better than uPVC?
Aluminium isn't 'better' — it's different. Aluminium wins on slim sightlines (down to 45mm vs uPVC's 70mm minimum), maximum span (5m+ unsupported vs uPVC's typical 2.4m), Crittall-style heritage replacement, large picture windows, corner glazing, and Passivhaus thermal numbers. uPVC wins on cost (40–50% cheaper for the same casement), proven 30-year UK track record, and traditional sash and bay configurations. The right answer depends on the project.
How much do aluminium windows cost vs uPVC?
In London (Q2 2026), fitted uPVC windows start around £550 for a small casement and run to £1,800 for a large tilt-and-turn. Aluminium windows start at £900 for a small Cortizo Cor 60 casement and run to £3,000+ for premium Schüco AWS 75.SI+ tilt-and-turn or Cor 70 Industrial Crittall replacements. Roughly speaking, aluminium costs 60–80% more than equivalent uPVC, and the gap widens on premium systems.
Are aluminium windows worth the extra money?
For contemporary new-builds, large openings, slim sightlines, and Crittall-style replacements, yes — uPVC genuinely cannot deliver the look or the structural span. For traditional casement and sash configurations on a typical semi-detached upgrade, no — modern uPVC delivers near-identical thermal performance at meaningfully lower cost. The honest test: if you walked past the finished window from 5m away, would you tell the difference? On a sash window: rarely. On a Crittall-style steel-look: instantly.
Which lasts longer — uPVC or aluminium?
Aluminium lasts longer in service: 30–40 years typical, with the powder-coat finish lasting 25 years and the frame structurally indefinite. uPVC lasts 25–30 years before frame discoloration, gasket degradation and hinge wear become noticeable. Both come with 10-year frame guarantees from us; Schüco aluminium extends that to 20 years. For listed buildings and properties expected to be held multi-generationally, aluminium's longer service life is meaningful.
Are uPVC windows still allowed in conservation areas?
Yes, increasingly so. Heritage uPVC products with timber-grain foils, ovolo or chamfered profiles, and slim sightlines are now approved by most London conservation officers as casement and sash replacements on rear and side elevations of period properties. Front elevations of Grade II listed buildings still typically require timber. Aluminium is rarely approved on conservation-area frontages even with heritage profiles; uPVC heritage is the more permitted material in those scenarios.
What is the slimmest uPVC sightline?
Modern slim uPVC casement systems achieve 70–75mm sightlines (e.g. Liniar EnergyPlus Slim, REHAU Total70). Standard uPVC sits at 90–105mm. Aluminium goes much slimmer: Cortizo Cor 70 Industrial at 45mm, Schüco AWS 70.HI at 77mm. If sightlines below 70mm are a brief requirement, aluminium is the only option.
Can uPVC windows replace Crittall steel-frame?
No. Crittall steel-frame replacement requires the slim 25–45mm sightlines that only steel-look aluminium systems (Cortizo Cor 70 Industrial, Schüco Jansen) deliver. uPVC's minimum 70mm sightline reads as a totally different product visually. For Crittall replacement, aluminium is the only credible specification.
Which is more thermally efficient — uPVC or aluminium?
Modern thermally-broken aluminium and modern multi-chamber uPVC are now within 0.1–0.2 W/m²K of each other. Mid-market uPVC casement (e.g. REHAU Total70) hits Uw 1.2 W/m²K with double glazing; mid-market aluminium (Cortizo Cor 70) hits Uw 1.4 W/m²K. At the top end, both reach Passivhaus: Schüco AWS 90.SI+ at Uw 0.79; high-end uPVC like REHAU Geneo at Uw 0.85. The thermal-performance gap aluminium had in the 1990s no longer exists in modern systems.
Should I mix uPVC and aluminium on the same property?
Yes, frequently. Many London projects use uPVC sash on the front (heritage, conservation-area approved) and aluminium bifold or sliding doors at the rear (contemporary extension). Mixing within a single elevation generally looks awkward, but mixing across elevations — front uPVC, rear aluminium — is a common and well-judged specification. Apex Glazing fits whole-property mixed installations across Richmond, Putney, Wimbledon and Chiswick regularly.
