How long do aluminium windows last?

Thirty to fifty years for the frame, with the powder-coated finish typically guaranteed for twenty-five. That is materially longer than uPVC at twenty to twenty-five, and it is one of the stronger arguments for the price difference.

What fails first, and it is not the frame

Sealed units, at 15 to 25 years. The glass fails long before the frame. It is a replaceable component and the frame stays.

Hardware, at 10 to 20 years. Handles, friction stays, locking mechanisms. All replaceable, all cheap relative to a window.

Gaskets, at 15 to 25 years. The rubber seals perish and get draughty. Replaceable.

So an aluminium window at year 25 usually needs new glass and new hardware in a frame that is half way through its life. That is a refurbishment, not a replacement, and it is far cheaper.

What shortens it

Coastal exposure. Standard powder coat does not survive salt air. Within about a mile of the sea you need a marine-grade specification, and without it the finish can fail in a few years rather than twenty-five.

Blocked drainage. Frames are designed to drain water out through weep holes. Blocked, the water sits against the sealed unit edge and kills it early. Clearing them takes minutes.

Dissimilar metal contact. Aluminium in direct contact with the wrong metal corrodes galvanically. This is a fitting detail, and it is one reason large or unusual installs are worth having done properly.

Making it last

Wash the frames twice a year — more at the coast. Clear the weep holes. Lubricate hinges and locks annually with a dry PTFE lubricant. Replace worn hardware promptly, because a dropped sash strains everything else. Do not paint over powder coat; if the finish is damaged, it can be repaired properly.