Aluminium vs uPVC windows: the verdict

Neither material is simply “better”. uPVC wins on warmth and price; aluminium wins on slimness, strength and finish. Score each criterion against your own priorities and the choice becomes clear.

Sightlines and looks

This is aluminium's headline advantage. Its strength lets it hold big panes in frames far slimmer than uPVC can manage, so you get more glass, more light and a crisp, contemporary look. Powder-coating comes in almost any colour and keeps it for decades. uPVC has narrowed the gap with foiled finishes, but for large picture windows and minimalist extensions, aluminium looks the part.

Warmth

uPVC is the naturally warmer frame — its hollow, multi-chamber profile is a better insulator than metal. Modern aluminium uses a “thermal break” (an insulating barrier between the inside and outside faces) to close much of the gap, and a good thermally broken system easily meets Building Regulations. But like for like, uPVC still edges it on the frame U-value, which is why it remains the value pick for warmth. See our best energy efficient windows guide for the numbers.

Cost

uPVC is the more affordable option, often by a meaningful margin, which is a large part of why it's the most-fitted frame in the country. Aluminium commands a premium for its slimness and finish. If budget is the deciding factor, uPVC almost always wins; our best upvc windows guide shows how to specify it well. Where cost is the barrier, funding and contribution options may be available, subject to eligibility and a home survey.

Security and lifespan

Both can be specified to PAS 24 with multi-point locking, so security comes down to the hardware, not the material. On lifespan, aluminium is exceptionally durable and its finish is very stable; quality uPVC also lasts decades but its colour is fixed for life. In conservation areas, note that neither modern frame is automatically permitted — check the rules for conservation areas first. And if your current frames are structurally sound, it's worth asking repair or replace first? before replacing them.