Can I change my windows in a conservation area?

The short answer

In a conservation area the default position is that window replacement remains permitted development. The exceptions are: an Article 4 direction removing the right (common in central and inner London), or the building being listed (in which case listed building consent is required separately). When an application is required, councils consistently approve timber sash or casement in matching profile, and consistently refuse uPVC or aluminium on principal elevations.

The permitted development position

Replacement of windows in a dwellinghouse is permitted development under Class A of Part 1 of Schedule 2 of the General Permitted Development Order 2015. Conservation area status by itself does not remove this right (although it does remove some other rights such as cladding and side extensions). The window replacement right falls away only where an Article 4 direction or listing applies.

When an Article 4 direction applies

Article 4 directions covering front windows are extensive across central and inner London. Westminster, Camden, RBKC, Islington, Hackney, Lambeth, Southwark, Hammersmith and Fulham, Wandsworth and Tower Hamlets all maintain Article 4 schedules covering window replacement on principal elevations. See our Article 4 directions guide for the borough-by-borough position.

Where Article 4 applies, replacement of front windows requires a householder planning application. The conservation area appraisal and the borough local plan heritage policies will be the principal material considerations.

When the building is listed

Listed building consent is required for any alteration to a listed window. The route, the test and the evidence are different from the conservation area regime. See our windows guide for listed buildings for the detailed approach.

Materials councils accept

• Timber sash or casement to match the original, including matching glazing bar profile and sightlines. Approved on the papers in most cases.
• Slim-profile double-glazed timber, where the proposed sightlines match the original. Approved in some boroughs, refused in others.
• Painted timber casement in matching pattern, where the original was casement. Approved.
• uPVC on principal elevations. Refused in almost all London Article 4 cases.
• Aluminium on principal elevations. Refused in almost all London Article 4 cases.
• Steel Crittall replacement in matching profile, where the original was steel. Approved.

The application process

1. Confirm whether Article 4 applies (Local Land Charges search or borough conservation area page).
2. Confirm whether the building is listed (NHLE search).
3. If application is needed, prepare existing and proposed elevations, window details at 1:5, a material specification and a short heritage or planning statement.
4. Submit via the Planning Portal as a householder application (or LBC for listed buildings).
5. Determination typically takes eight weeks from validation.

Outbound references: General Permitted Development Order 2015 and Historic England traditional windows advice.