Aluminium and timber are both premium window materials, but they serve almost opposite briefs. Aluminium, at £550 to £1,300 fitted per casement, is the modern choice: slim frames, zero maintenance, suited to extensions and contemporary new builds. Timber, at £900 to £2,000 fitted per casement, is the heritage choice: rich character, planning-authority acceptance and, with proper care, the longest lifespan of any window frame material. Both sit above the uPVC band of £400 to £1,000, so neither is a budget pick. If you already know which material you prefer, the aluminium window calculator and the timber window calculator will price your own home precisely.
The headline comparison
The table below gives the side-by-side picture for a standard fitted casement window. All cost figures are per window, fully installed, in 2026 UK prices.
| Dimension | Aluminium | Timber |
|---|---|---|
| Cost per window (fitted) | £550–£1,300 | £900–£2,000 |
| Premium over uPVC | Around +30 to 40% | Around +60 to 100% |
| Lifespan | 30 to 40 years | 30 to 60 years (if maintained) |
| Maintenance | None (powder-coated) | Repaint every 8 to 10 years |
| Thermal performance | 1.0 to 1.4 W/m²K | 1.0 to 1.4 W/m²K |
| Sightlines | Slim, more glass | Wider, traditional |
| Best suited to | Modern homes, extensions | Period, listed, conservation-area homes |
Source: DGCC 2026 dataset. Both materials are premium over uPVC (£400 to £1,000 fitted).
Cost
Cost is the sharpest difference between the two. An aluminium casement sits in the £550 to £1,300 range per window fitted, while the same opening in timber runs £900 to £2,000. On a ten-window Victorian terrace that gap can add up to several thousand pounds, and timber has not yet started paying you back in maintenance savings the way aluminium does (aluminium needs none; timber needs paint). That said, timber's higher cost is partly a reflection of skilled joinery: each frame is largely handmade, which is both why it costs more and why it looks as good as it does. For a quick side-by-side against the uPVC baseline, the uPVC vs aluminium comparison shows where each material sits in the wider market.
Best Buy Aluminium for cost. It is significantly cheaper than timber, with no maintenance spend to add on top.
Looks: modern versus heritage
This is where the two materials diverge most clearly, and where the choice often makes itself. Aluminium frames are slim and precise, with clean sightlines that suit contemporary architecture, large glazed openings and rear extensions. The powder coating holds colour without fading, and the overall effect is sharp and minimal. Timber frames are wider and warmer, with the grain and moulding detail that heritage buildings call for. A slim aluminium frame on a Georgian townhouse looks wrong in a way that is hard to overlook; a handmade timber sash in the same opening looks entirely natural.
For homes with sash windows in particular, timber is often not just the better-looking option but the only one that will satisfy a planning officer. Our guide to sash windows covers the geometry and maintenance of the traditional sliding sash, which is almost always timber in a period context.
It depends Depends entirely on your property. Aluminium wins on modern homes; timber wins on period and conservation-area homes.
Lifespan and maintenance
On paper, timber offers the longer potential lifespan: 30 to 60 years for a properly maintained frame, against 30 to 40 years for aluminium. The catch is that word "maintained." Timber needs repainting every 8 to 10 years to hold its lifespan advantage. Miss a cycle and water gets into the grain; miss two and you are looking at repairs or early replacement. Aluminium, by contrast, is a fit-and-forget material. Powder coating holds its colour for decades with nothing more than an occasional wipe. For a busy household, or a landlord managing multiple properties, that difference in upkeep is a real cost even if it does not show up in the purchase price.
Aluminium's maintenance-free life also makes it the cleaner comparison against uPVC, where both materials share the same hands-off ownership experience. Timber is in a different category, closer to a quality wooden floor than a plastic window: beautiful, lasting, but only if you look after it.
Worth it Aluminium for most owners. Timber's lifespan advantage is real, but only if the repainting schedule is kept.
Thermal performance
Both materials can reach the A-rated, Part L compliant standard of 1.0 to 1.4 W/m²K. Timber is a natural insulator and performs well without any additional engineering; aluminium closes the gap with a polyamide thermal break running through the frame. In practice, the glass unit, the spacer bar and the installation quality matter far more than the frame material for thermal performance. Neither aluminium nor timber has a meaningful advantage over the other here. Both are well ahead of single glazing and comfortably meet what Part L requires for replacement windows in existing homes.
It depends A practical draw. The glass specification matters more than whether the frame is metal or wood.
Which home each suits
Aluminium suits modern homes, large openings and extensions. The slim frames maximise glass area, the material handles big spans without deflecting, and the aesthetic is right for contemporary architecture. If you are replacing windows on a 1990s or later build, adding a glazed rear extension, or fitting floor-to-ceiling glazing, aluminium is almost certainly the better fit.
Timber suits period homes, listed buildings and conservation areas. Many local planning authorities require timber (or a timber-effect material) for properties in sensitive locations, and the look of a well-made timber frame on a Victorian or Edwardian house is simply right in a way no other material matches. The uPVC vs timber comparison covers the choice between the budget and heritage options on older properties, which is a separate and equally common decision.
It depends Aluminium for modern properties and large openings; timber for period, listed and conservation-area homes.
I install both, and the job tells you which one it wants almost straight away. Walk up to a 1920s bay-fronted semi and you can see timber is the right answer before you have even looked at the drawings. Walk up to a 2010 executive new build with a big kitchen extension and aluminium is obvious. Where people go wrong is trying to impose one on the other, and paying a lot of money for a result that looks off. Neither is a cheap option, so get the choice right before you spend.
Tom Bradley, FENSA-registered installer
The verdict
The right answer depends on your home. Choose aluminium for modern properties, large openings and extensions: it is the cheaper premium option, needs no maintenance and delivers slim, contemporary sightlines that suit new architecture. Choose timber for period, listed and conservation-area homes: it is the only material that looks genuinely right on older buildings, and in many sensitive locations it is what the planning authority will require. If you are comparing either of these against the mainstream alternative, see the uPVC vs aluminium and uPVC vs timber pages for the full picture. Neither aluminium nor timber is a budget pick, so price your project carefully before committing.
Frequently asked questions
A fitted aluminium casement costs roughly £550 to £1,300 per window, while the equivalent in timber runs £900 to £2,000. Timber is therefore between 40% and 60% more expensive at the upper end, though both sit above uPVC in the £400 to £1,000 band. The gap reflects slower fabrication and material costs.
They can, but only if maintained. A properly painted and preserved timber frame lasts 30 to 60 years, against 30 to 40 years for aluminium. Neglected timber rots and fails far sooner. Aluminium simply gets on with the job without any attention, so the practical lifespan advantage of timber is conditional.
Timber is often the preferred or required material in conservation areas and for listed buildings. Many planning authorities will not approve aluminium, even in heritage-style finishes, for prominent elevations in sensitive locations. Always check with your local authority before ordering.
Yes. Both materials can reach the A-rated, Part L compliant standard of 1.0 to 1.4 W/m²K with the right glass specification. Timber is a natural insulator and aluminium uses a polyamide thermal break. Neither has a significant advantage; the glass unit and spacer determine most of the performance.