Can you replace steel windows in a listed building or conservation area?

What counts as a heritage steel window?

Most original steel windows in UK homes date from the 1920s to the 1950s, especially on Art Deco and interwar houses. They have slim sections, horizontal glazing bars, opening casements and sometimes curved corner bays. They are often described as Crittall-style after the best-known historic manufacturer.

Repair or replace?

If the frames are structurally sound, refurbishment can keep original fabric for less money: rust treatment, repairs, new seals and recoating. If sections are badly corroded or bent, like-for-like replacement with modern heritage-profile steel is usually better value. Conservation officers often prefer repair where it is practical, so a condition report helps the conversation.

What will a conservation officer want to see?

Usually drawings comparing existing and proposed sections, bar layouts and opening lights, plus details of glazing and colour. Slim double-glazed units in heritage sections are often acceptable where uPVC would not be. We provide drawings and specifications to support an application.

Will replacement windows meet building regulations?

Replacement windows in England must meet Part L energy rules, currently a U-value of 1.4 W/m²K or better, unless relaxations apply for historic buildings. They also need safe escape windows where required and suitable ventilation. Listed buildings can have exemptions where compliance would harm their character.

How long does the process take?

Listed building consent typically takes around eight weeks once an application is validated, though it varies by council. Manufacture is usually five to seven weeks from signed-off drawings.