PVC-U vs aluminium vs timber: which should you choose?

PVC-U

The most widely fitted material in the UK, and the most competitive on price. Modern multi-chambered systems perform superbly thermally and need almost nothing from you beyond cleaning.

The compromise is frame width. Because PVC-U is not structurally strong, sections are thicker and you see more frame and less glass.

Aluminium

Strong enough to hold large panes in slim frames, which is exactly why contemporary extensions use it. Powder coating gives an excellent, durable finish in any RAL colour.

It costs meaningfully more than PVC-U, and thermal performance depends entirely on the quality of the polyamide thermal break — this is where cheap aluminium falls down.

Timber

Unbeatable for authenticity and often the only material acceptable on listed properties. Engineered, factory-finished joinery is far more stable than the softwood of decades past.

You are signing up for recoating roughly every eight to ten years. If that suits you, timber will outlast everything else.

A quick way to decide

Match the material to your dominant priority.

• Best value and lowest upkeep → PVC-U
• Maximum glass, modern architecture → aluminium
• Period authenticity or planning constraints → timber
• Traditional look without maintenance → flush sash PVC-U or heritage aluminium