Secondary Glazing for Listed Buildings

In many London boroughs, slim reversible secondary glazing to an internal reveal does not require consent at all. Where a borough does require it — and Westminster and Kensington & Chelsea often do — applications are routinely approved when the submission demonstrates reversibility, slim sightlines and a sympathetic finish.

We provide the technical drawings, product specification and reversibility statement your conservation officer will ask for, at no charge, as part of the survey.

The secondary frame is mounted onto a timber subframe that is itself fixed into existing plaster or lining, never through mouldings, architraves or the sash box. Removing the system leaves only filled screw holes in modern lining material.

Where reveals are irregular — as they almost always are in Georgian properties — every unit is surveyed and manufactured to the measured opening rather than trimmed on site.

Sightlines are the detail conservation officers examine first. We use slim 20-25mm aluminium sections, aligned with the horizontal meeting rail of the primary sash so the secondary frame visually disappears behind the original glazing bars. Finishes are powder-coated to match existing joinery paint, including traditional heritage whites and off-whites.