Replacing Windows in a Grade II Listed Building

Owning a Grade II listed home means the windows are part of the listing, not just part of the house. Any change to their appearance, material or glazing pattern needs listed building consent from the local planning authority before work starts, and replacing without it is a criminal offence rather than a civil planning matter.

That sounds daunting, but the process is predictable once you know the sequence. We handle listed projects from our base in Cranbrook near Exeter across Devon, Cornwall, Dorset and Somerset, and the steps below are the ones we walk every owner through.

Step one: record what is there now

Before anyone talks about new windows, every opening is photographed inside and out, measured and its profile recorded. Officers want to know which frames are original, which are later replacements and which are beyond saving. A later casement put in during the nineteen seventies carries far less weight than an early sash with its original crown glass.

This record becomes the backbone of the application. It also stops arguments later, because everyone is working from the same evidence.

Step two: talk to the conservation officer early

Most authorities offer pre application advice. Using it is the single best way to avoid a refusal. A short site visit or an email with photographs tells you whether the officer will accept replacement at all, whether they want repair instead, and which details matter most to them on your particular building.

Step three: drawings and specification

An application built around a brochure rarely succeeds. What works is a drawn proposal that copies the original: section details through the frame and sash, glazing bar profiles, sightlines and the paint colour. We prepare these drawings and product documentation for the application at no charge.

• Timber frames, normally painted softwood or engineered hardwood
• Slim 14mm double glazed units with warm edge spacers where glazing is allowed
• Glazing bars that match the original pattern and width
• Putty line or slim bead detail rather than a chunky modern bead
• Like for like opening method, sash for sash and casement for casement

Step four: the decision and the lead time

A straightforward window application typically takes eight to twelve weeks to decide in the South West authorities we work with. We do not start manufacture until consent is granted. Once it is, bespoke timber units usually take eight to twelve weeks to make, so a realistic whole project runs from four to six months.

Step five: fitting without damaging the fabric

Listed openings are often out of square and sit in lime mortar or soft stone. Frames are scribed to the opening rather than the opening cut to the frame, and making good uses compatible materials. Any conditions attached to the consent, such as sample approval or a paint colour sign off, are met before the final visit.

Questions people ask