A Crittall-style aluminium window replicates the look of an original steel window — slim flat-faced frames, black finish, fine glazing bars — but with a thermal break, modern gaskets and a whole-window U-value around 1.3 W/m²K. Original steel windows had none of those things.
Original Crittall windows are beautiful and terrible. Single glazed, no thermal break, and prone to rusting from the inside out — as the steel corrodes it expands and cracks the surrounding masonry. Most of what survives from the 1920s–50s is at the end of its life.
Aluminium is the natural successor: it is the only common material that can be extruded into a section slim enough to look like steel while still carrying a double-glazed unit and a polyamide thermal break. uPVC cannot get close — the profile is simply too fat to convince anybody.
This is where heritage aluminium earns its keep. Most conservation officers will refuse a standard uPVC or chunky aluminium profile in a conservation area but will accept a slim, flat-faced steel-look aluminium window, particularly where the original was itself steel.
For a listed building, listed building consent is required regardless of material, and the answer depends on the officer and the building. Get pre-application advice before you order anything.
| Job | Typical cost |
|---|---|
| Heritage / steel-look window, per panel supplied & fitted | £1,100 – £1,900 |
Ranges include VAT and installation. Final price depends on size, spec, access and site condition — a survey gives you a fixed number.
Usually yes, where the original windows were steel. Slim flat-faced aluminium profiles with a putty-line bead are widely accepted by conservation officers, because the sightline closely matches the original. Always confirm with your local planning authority before ordering — and note that a listed building needs listed building consent regardless of material.
Expect around £1,100–£1,900 per panel supplied and fitted. They cost more than a standard casement because the profiles are more complex, glazing bars add labour, and the tolerances are tighter.
That is precisely the point of doing it in aluminium. A modern heritage profile is thermally broken and double glazed, so you get a U-value around 1.3 W/m²K instead of the roughly 5.0+ of an original single-glazed steel window.
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