Quick Answer
Choose timber for period homes, conservation areas, warmth, and repairability. Choose aluminium for contemporary architecture, slim sightlines, and minimal maintenance. Cost is similar at the premium end. Timber insulates far better.
Side-by-Side Comparison
| Factor | Timber | Aluminium |
|---|---|---|
| Cost (per window) | £1,200 – £2,500 | £800 – £2,500 |
| Lifespan | 60–100+ years | 25–40 years (finish) |
| Thermal conductivity | 0.13 W/mK (excellent) | 160 W/mK (poor, needs thermal break) |
| Frame width | 55–70mm typical | 45–65mm (slimmer possible) |
| Maintenance | Repaint every 8–12 years | Wipe clean only |
| Repairability | Fully repairable — sand, splice, repaint | Not repairable — replace entire unit |
| Conservation areas | Accepted everywhere | Rarely accepted |
| Sustainability | Carbon-negative (timber stores CO&sub2;) | High embodied carbon (smelting) |
| Appearance | Warm, traditional, real shadow lines | Clean, modern, industrial |
Thermal Performance
This is where timber wins decisively. Aluminium conducts heat approximately 1,200 times faster than timber. Even with modern polyamide thermal breaks (a plastic insert that interrupts the metal), aluminium frames still create cold spots around the window perimeter.
In winter, you can feel the difference. A timber frame feels warm to touch. An aluminium frame, even with a thermal break, feels noticeably cooler. This creates condensation risk on the frame itself — something that rarely happens with timber.
Appearance
This is not a matter of better or worse — it’s a matter of architectural context. Aluminium’s slim, sharp profiles suit contemporary buildings, glass extensions, and minimalist designs. The powder-coated finish is consistent and precise. It looks engineered.
Timber looks grown, crafted, substantial. Mortise-and-tenon joints, real glazing bars with shadow lines, weight when you lift the sash. In a Victorian terrace, Edwardian semi, or Georgian townhouse, nothing else looks right.
Maintenance
Aluminium wins here. Clean it once a year, oil the hinges, that’s it. No painting, no sanding, no coatings.
Timber needs repainting every 8–12 years. That’s a genuine commitment. But it’s also what makes timber repairable — a scratched or damaged timber frame can be sanded and refinished. A scratched aluminium frame cannot. The powder coating cannot be meaningfully repaired on site.
When Aluminium Is the Better Choice
We make timber windows, but we’ll be honest: aluminium is better in certain situations:
- Contemporary or modern architectural design
- Very large openings where slim frames matter most
- Coastal or extremely exposed positions (if Accoya is not in budget)
- Properties where zero maintenance is a hard requirement
The Verdict
For period homes, conservation areas, and anyone who values warmth and craftsmanship: timber.
For contemporary homes, glass extensions, and anyone who wants absolute minimum maintenance: aluminium.
Avoid: putting aluminium in a Victorian terrace. It never looks right and conservation officers will reject it.
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Are aluminium windows better than timber?
It depends on the property. Aluminium suits modern, minimalist architecture with its slim profiles and industrial look. Timber suits period properties and traditional homes. Thermally, timber performs significantly better. Aluminium is lower maintenance but cannot be repaired — damage means replacement.
How much more do aluminium windows cost than timber?
Premium aluminium windows (like Schuco or Smart Systems) cost roughly the same as timber — £1,200–£2,500 per window. Budget aluminium is cheaper at £800–£1,200 but uses thicker frames and lower-grade thermal breaks.
Do aluminium windows get cold?
Without a thermal break, aluminium frames conduct heat 1,500 times faster than timber and feel noticeably cold in winter. Modern aluminium windows use polyamide thermal breaks to reduce this, but they still perform worse thermally than timber.
How long do aluminium windows last?
25–40 years for the powder-coated finish. The aluminium itself does not rot or corrode significantly. However, mechanisms, seals, and hinges wear out in 15–25 years and may not be replaceable if the manufacturer has changed ranges.
Can you get aluminium windows in a conservation area?
Rarely. Most conservation officers reject aluminium because it does not match the appearance or material of original windows. Timber is required in the vast majority of London conservation areas.