Replacing windows in Horsham's conservation areas

Most houses in Horsham can have their windows replaced without planning permission, as long as the new windows look broadly similar to the old. The places where that changes are few and well defined. If your house is in one of them, settle the permission question before you choose a window.

The four conservation areas in the town

• Horsham, designated in 1974 and reviewed in 2001, covers the historic core: the Causeway, Carfax, Middle Street, Denne Road and East and West Streets. The appraisal notes Horsham stone used for roofs, paving and walls, and many timber sash and casement windows with glazing bars.
• London Road, designated in 1984, runs from Albion Way to Springfield Road and includes the 1820s stuccoed terrace at Brunswick Place. The appraisal says sash windows are the prevailing style.
• Richmond Road, designated in 1989, covers houses in Wimblehurst Road, Gordon Road, Hurst Road and Richmond Road, and was extended in 2022 to take in 84, 86 and 88 Hurst Road. The appraisal describes timber sashes as the prevailing style, with two-storey bays.
• Park Terrace Gardens is the fourth, a smaller area in the town.

All three appraisals that we have read say much the same thing about windows: the main threat to the character of the area is timber sashes and casements being replaced with plastic, because uPVC sections and proportions cannot match historic joinery. That is the council's view, and it will shape any application.

Article 4 directions that affect windows

An Article 4 direction removes permitted development rights, so work that would normally need no application needs planning permission. Horsham District Council has many small directions, most of them old and site-specific. Two matter for windows:

• 11, 13, 15 and 19 Denne Road, in the town conservation area, where the direction covers window alterations along with terracotta and tile-hanging details.
• Slinfold conservation area, where the direction covers alterations to a house that front a highway, watercourse or open space and involve removing an external window. More on Slinfold.

If you are unsure whether a direction applies to your house, Horsham District Council's planning team can confirm it, and the council publishes the boundaries as open data.

Listed buildings

Any change to the windows of a listed building needs listed building consent, inside or out. Horsham has many listed buildings, from St Mary's Church at the end of the Causeway to cottages in the surrounding villages. You can check a building on the Historic England list. For a listed house the usual answer is to repair or replace in timber, or to add secondary glazing inside. Secondary glazing for a sash opening of about 900 by 1800 mm costs an indicative £450 to £1,200 including VAT, as a market range rather than a quote.

What we suggest

1. Check whether the house is listed, in a conservation area, or covered by one of the directions above.
2. If it is, talk to the council before choosing. Timber box sash is from £2,650 installed per window and is often what the council expects on a front elevation.
3. If it is not, a uPVC sliding sash or flush casement in a heritage colour is the usual choice and costs much less.