Listed Building Window Rules

A listed building is protected under the Planning (Listed Buildings and Conservation Areas) Act 1990. The whole building is protected — including interior features. Changes require Listed Building Consent from the council's conservation team. Unauthorised changes are a criminal offence and can require reversal at the owner's cost.

Grade I is the most protected (2.5% of listed buildings) — significant changes rare. Grade II* is the next tier (5.8%) — case-by-case. Grade II is the majority (91.7%) and includes most listed homes — sensitive replacement windows are often possible with the right materials and design.

Timber sash or timber casement with slim double glazing (14mm units) usually meets the conservation officer's requirements. Some officers accept certain heritage aluminium systems on Grade II properties. uPVC is almost never accepted on listed buildings, regardless of how convincing the appearance.

Listed Building Consent applications are separate from planning applications (though often submitted together). They require: measured survey of existing windows, photos, elevation drawings of proposed windows, and a Heritage Impact Assessment for anything more than direct replacement. Expect an 8–12 week decision period.

For anything beyond straightforward like-for-like replacement, employ a heritage architect or conservation consultant. Their fee (£1,500–£4,000 typically) pays for itself in approved applications and avoided enforcement notices. A specialist will also know which timber suppliers can match the exact original section.