Aluminium vs uPVC windows

These are the two materials most replacement windows are actually chosen between, and the honest answer is that neither wins outright.

The difference that matters day to day

Aluminium is stronger than uPVC, so the same structural job needs far less frame. A uPVC casement frame is usually 70mm or more; the aluminium equivalent is around 55mm. Through the same hole in the wall that converts to roughly 15 to 20% more visible glass. It is the thing you notice every single day, and it is the main reason people pay the difference.

Where uPVC wins

Cost. Aluminium runs 25 to 50% more. On a whole house that is a serious number.

Thermally, marginally. Modern thermally broken aluminium reaches around 1.2 to 1.4 W/m²K, which meets Part L comfortably. Good uPVC is in the same band. Anyone claiming a large real-world heating difference between the two is overselling.

Where aluminium wins

Lifespan. 30 to 50 years against 20 to 25, with the powder-coat finish typically guaranteed 25 years. Aluminium does not yellow, warp or go brittle.

Colour. Any RAL, matt or satin, and different colours inside and out. uPVC is foiled, so you choose from a range rather than specifying freely.

Large openings. Aluminium is stiffer, so it carries big panes without deflecting. Above a certain size uPVC simply is not the right material.

How to decide

A house you intend to keep, on an elevation you look at: aluminium, and you will not regret it. A rental, a tight budget, or a rear elevation nobody sees: uPVC, and paying more would be a waste. Large glazed openings, or anything where sightlines are the point: aluminium, without much argument.

Plenty of houses are best served by both — aluminium on the front and the big openings, uPVC round the back. Nothing wrong with that, and we supply both.