uPVC vs Aluminium vs Timber Windows Compared

The three materials at a glance

uPVC: the default for good reason

Modern uPVC profiles are multi-chambered, steel-reinforced and welded at the corners, and a decent system will comfortably do thirty years with nothing more than washing. It is the cheapest option by a distance and the easiest to get parts for.

Its weaknesses are visual: the frames are thicker than aluminium, so you lose glass area, and very large openings need reinforcement. Dark foils on a south-facing elevation get hot and can, in poor-quality profiles, distort over time — worth asking about the foil warranty.

Aluminium: slim, strong, expensive

Aluminium's advantage is strength-to-size. It spans wide openings with narrow frames, which is why it dominates bifolds and big picture windows. Powder-coated finishes are extremely durable and available in any RAL colour, and the material shrugs off coastal weather.

It costs substantially more and, without a proper thermal break, conducts heat. Every quote should state that the system is thermally broken and give a whole-window U-value.

Timber: beautiful, demanding

A well-made engineered timber window in a period property looks better than anything else and can outlive everyone reading this. Factory-finished paint systems have improved enormously, and repainting every six to eight years is realistic rather than every two.

The catch is that neglect is expensive. Once water gets past the finish into an end grain joint, rot follows and repairs get involved. On an exposed elevation in the west of Scotland, timber needs an owner who will actually maintain it.

Which suits which property

• Post-war semi or ex-local-authority house: uPVC, almost always.
• Modern extension or garden room with wide glazing: aluminium.
• Victorian or Edwardian villa on a prominent street: timber, or high-quality timber-alternative uPVC sash.
• Coastal or highly exposed property: aluminium or uPVC.
• Conservation area or listed building: check with the local authority first; timber is often required.

Mixed material approaches

There is nothing wrong with using different materials in different places. Aluminium across the back of the house for a wall of glass, uPVC for the bedrooms and a timber or timber-effect sash on the street elevation is a very common and cost-effective mix.

Just agree the colours across the whole house at the start so the anthracite on the bifolds matches the anthracite on the windows — RAL codes vary between manufacturers.

Whole-life cost, not just purchase price

Judged over thirty years the gap between the materials narrows considerably. uPVC is cheapest to buy and needs nothing but washing, but is most likely to be replaced first. Aluminium costs the most upfront and will very likely still be there in forty years with only cleaning. Timber sits between the two on purchase price but carries a real recurring cost in redecoration — budget roughly £40 to £80 per window every six to eight years if you pay someone.

Resale also matters. On a period property, sympathetic timber or a convincing timber-alternative sash protects value in a way that a chunky white casement does not. On a modern estate house, nobody pays a premium for aluminium.

The other whole-life factor is parts. uPVC hardware is standardised and cheap, so a broken hinge is a £70 fix a decade from now. Specialist aluminium and bespoke timber systems can be far harder and dearer to source parts for once the original supplier has moved on.

Getting a like-for-like comparison

Ask each installer to price the same house in two materials. You will learn more from that single sheet of paper than from any brochure. We quote in writing across Central Scotland and can price alternatives side by side.