Glossary
Class B roof alterations
Class B covers many roof enlargements on houses in England, such as dormers and hip-to-gable changes, within volume and plane limits. Front elevations facing a highway are tightly restricted.
Materials should be similar in appearance to the existing house, and other PD conditions still apply.
Roof PD classes differ by nation; check the order that applies locally.
Official source: Permitted development technical guidance (GOV.UK). Checked 27 October 2026.