Each material wins on something different. uPVC asks least of you and costs least. Aluminium gives the slimmest frames and the most glass. Timber is the only one you can recolour and repair indefinitely. A fourth option, alu-clad timber, exists precisely because those trade-offs annoyed people, and UK comparisons rarely mention it.
We manufacture windows in uPVC, Nordic pine, meranti, alu-clad pine and alu-clad meranti. We do not make aluminium-only windows.
That matters for how you read this page. Almost every comparison of these materials is published by a company that sells one of them, and the conclusion tends to match the product range.
We sell four of the five options discussed here, so we have less to defend than most, and we have no reason to talk you out of aluminium where aluminium is the right answer.
The section on aluminium below says where it genuinely beats what we make. Take that as the reason to trust the rest.
Two rows in those tables carry most of the decision. Frame width determines how much glass you get in the same hole. Colour changeable later determines whether your choice today is reversible.
The difference is structural. Aluminium is strong enough to hold a large pane in a narrow frame, so an aluminium window puts more glass and less frame in the same opening. uPVC needs more material to achieve comparable rigidity, which is why uPVC frames look chunkier beside aluminium ones.
Thermal behaviour runs the other way, and for the same reason. Metal conducts heat. Aluminium windows therefore need a thermal break, an insulating barrier built into the profile to interrupt the path from outside to inside. Modern aluminium systems do this well, and the point stands that aluminium starts from behind and engineers its way level.
uPVC starts from in front. The material is a poor conductor by nature, so the profile does the insulating work without a barrier having to be designed into it.
Maintenance is close to identical. Both wash clean, neither needs painting, and neither rots. Our own guidance for aluminium surfaces is a pH-neutral cleanser between 5 and 8 and a wash whenever you wash the windows, because washing is itself what protects the finish.
Better at three specific things, and not better in general.
Slimmer sightlines. If maximising glass matters, on a picture window, a large opening or a contemporary elevation, aluminium wins and no amount of uPVC engineering closes that gap.
Large spans. Strength per millimetre of frame means aluminium handles bigger units without reinforcement becoming the design constraint.
Powder-coated finish durability. A powder coat on metal is a hard, scratch-resistant surface.
Where uPVC leads: cost, inherent insulation, and the sheer absence of anything to think about. Where timber leads: repairability and the freedom to change colour.
So the question is not which material is better but which of those axes you care about. A rear extension where the garden view is the whole point argues for aluminium. A four-window replacement on a 1930s semi, where nobody will notice 8mm of frame width, argues for uPVC or alu-clad.
Yes, generally, and the ordering across the four materials is fairly consistent. uPVC sits lowest. Aluminium and timber sit higher. Alu-clad timber sits highest, because it is a timber window with an aluminium window's outer skin on it.
Two things distort that ordering more than the material does. Size and configuration, since a large multi-panel unit in uPVC can cost more than a small aluminium one. And specification, since glazing choice, colour and hardware move the figure on every material.
For an actual figure on your own configuration, use the price calculator rather than a comparison article. Any number quoted here would be wrong for most readers and out of date for the rest.
Worth separating cost from value on this decision. The cheapest window that needs replacing in fifteen years is not cheaper than one that lasts thirty, and the more expensive window that gives you a view you look at every day is not merely more expensive.
Timber wins on two things that matter to some people enormously and to others not at all.
Repairability. A timber window can be sanded, filled, repainted and repaired indefinitely. Damage that would end a uPVC frame is a Saturday's work on timber. Nothing else in this comparison offers that.
Colour freedom, permanently. Timber takes any colour and takes a different one in ten years. On uPVC, aluminium and composite the colour is a decision for the life of the window.
The cost is maintenance, and it is a real cost rather than a rhetorical one. Our own guidance sets out what it involves:
Pine comes factory-treated with preservative and a surface finish and needs periodic retreatment with stain or paint; mahogany arrives primed and needs a top coat after installation, then two retreatments during the first year, then an annual inspection.
The rule of thumb we use is a good one to know: the surface treatment is still doing its job while water forms droplets on the wood rather than soaking in.
South and west-facing elevations weather fastest, and horizontal mouldings weather faster than anything else on the frame. Those are the places to look when deciding whether this year is a retreatment year.
No. A woodgrain or wood-effect finish on uPVC is a surface treatment, and thermal performance comes from the profile beneath it: the chambers, the reinforcement and the glazing unit. Changing the appearance of the outer face does not change how the window insulates.
Two genuine differences, neither thermal. A foil or coloured finish carries a supplement over standard white on most ranges. And a coloured or dark surface absorbs more solar heat than a white one, which is a consideration for the profile specification rather than for the insulation.
Where wood-effect uPVC does useful work is on properties where a timber appearance matters and a timber maintenance cycle does not appeal. It reads as timber from the pavement and washes like plastic.
Where it disappoints is close up and on the inside face, and that is worth seeing in person before ordering. If the timber appearance matters at arm's length, alu-clad with a real timber interior is the honest answer rather than a printed finish.
Work down this list and stop at the first line that describes you.
Two constraints that override the list. Conservation areas and listed buildings may restrict material, and that is a planning question to settle before a preference. And exposure: on a coastal or heavily weathered elevation, the maintenance difference between materials stops being theoretical.
