Aluminium or timber bi-folding doors: an honest comparison

Aluminium is strong for its weight, so frames can be slim and still carry large panes. Powder coating gives a wide colour range and a finish that does not need recoating, while anodising suits a more metallic, industrial look.

Modern aluminium systems use thermal breaks to separate the inner and outer faces, which is what stops a slim frame becoming a cold bridge. Without them, a metal frame will condense, and the reveal around it will stay cold.

Timber suits older buildings and looks right beside brick and stone. It can be repaired rather than replaced, which matters on a listed or heritage property, and it feels warmer to the touch than metal on a winter morning.

It needs recoating every few years, more often on a south or west elevation, and the joints need watching. Factory-finished timber holds its coating far longer than timber painted on site.

Timber-aluminium combines a timber inner face with an aluminium outer shell. You get the look from inside and the weather resistance from outside, at a price above either material on its own.

Ask what you will notice in five years. Aluminium will look the same after a wash. Timber will look better with attention and worse without it.

If the property is listed or sits in a conservation area, the material may be decided for you by the conservation officer, and that conversation comes before the quote.