Timber box sash windows in Sevenoaks, for listed houses

Timber box sashes on weights and pulleys are the right window for a listed building, and in Sevenoaks there are plenty: the High Street conservation area alone has over one hundred listed buildings in 20 hectares. They cost from £2,650 installed per window, with no upper figure given until the survey, because listed joinery is made to each opening.

Eighteenth-century red brick front with white painted six-over-six sash windows and a black panelled door, typical of Sevenoaks High Street

When timber is the answer

Listed buildings. On a listed house in the High Street or a village centre, new windows cannot go in without listed building consent. Officers expect timber, usually in the original pattern, and sometimes single glazing.
Flats in conservation areas. A flat in a converted villa needs planning permission for new windows. The council may ask for timber when it decides the application.
Where an Article 4 direction controls windows. We have not found one in force in Sevenoaks or the villages on this site, but the Otford appraisal recommended one, so check before you plan.

When timber is not the only answer

For an unlisted house, including one inside a conservation area, uPVC sash does the same job on the street for a little over half the cost, and aluminium heritage sash gives slimmer frames. Painted sashes on a Sevenoaks house are due their first repaint around three years after fitting, and regularly after that; on a three-storey Granville Road villa every one of those repaints needs scaffold. The installer fits timber sashes but does not offer a repainting service, so keeping them painted is the homeowner's responsibility. Compare the same Vine Court Road house in uPVC and in timber.

Repair first, if the frames are sound

The council's design guidance says original windows can often be repaired, and sometimes slim double-glazed units can go into the historic frame. Where consent for replacement will not be given, secondary glazing inside is the usual way to cut draughts. Secondary glazing for a sash opening of about 900 by 1800mm costs an indicative £450 to £1,200 including VAT, a market range rather than a quote.

Georgian red brick house of the kind found in Westerham, with white six-over-six sash windows, a pedimented doorcase and daffodils along a low wall

Illustrative example of a typical job

Listed Georgian house near Westerham Green: six timber sashes

A listed Georgian brick house of the polite 18th-century kind the Westerham appraisal describes around the Green and up Vicarage Hill. Listed building consent is needed, and the conservation officer will expect timber.

Six timber box sashes on weights and pulleys, six-over-six with slim putty-line bars
Painted white, with slim double glazing only where consent allows it
First coat of paint due around year three, then at regular intervals; the installer does not repaint, so this falls to the owner

From £15,900, supplied and fitted, including VAT

Planning a listed job? Read the planning guide, then ask for a survey.