Sash windows in conservation areas: what officers actually look for

If your street is a conservation area, replacing windows means satisfying a conservation officer — and the process is far less mysterious than it looks. Officers assess a handful of concrete things, and knowing them beforehand is most of the battle.

Material. Timber, almost always. A conservation officer can spot uPVC pretending to be timber from the pavement; genuine timber construction is the entry ticket. [Our windows: meranti or pine, traditional joinery.]

Proportions. Period windows follow period proportions — Georgian sashes are tall and narrow, Victorian ones broader. Replacements are expected to match the openings and the rhythm of the street, which made-to-measure handles by definition.

Glazing bars. Where the street has six-over-six or two-over-two patterns, officers want real bars — timber glazing bars with the pattern of the originals, not stick-on strips between panes. Our bars are true divided-light timber, made to match a photo of your originals if you send one.

How it opens. Vertical sliding sashes where the street has sashes. Cords, weights and traditional operation are part of what's being protected — and they're how we build anyway.

Sightlines and glass. Some officers ask about the thickness of glazing units and how they sit in the frame. Requirements vary street by street. If yours comes with specific glazing conditions — slim units, particular sightlines — tell us before you order and we'll confirm exactly what's possible and what it costs, in writing, before you commit.

A note on listed buildings. A conservation area and a listed building are different regimes. Listed buildings need listed building consent and usually a conversation with the council before anything else; this article is about conservation areas. If you're listed, talk to your conservation officer first — then to us.

Send us your street's requirements and a photo of the originals, and the drawings you approve will be the drawings the officer sees. Get in touch