Do you need planning permission for a loft conversion?

Permitted development in outline

Permitted development commonly allows a rear or side roof extension within volume allowances of 40 cubic metres for terraced houses and 50 cubic metres for detached and semi-detached houses, provided the work does not extend beyond the existing roof slope at the front and does not exceed the highest part of the roof.

When planning permission is normally required

Permission is usually needed where any of the following apply.

• The property is a flat, maisonette or converted building
• The property is listed or in a conservation area
• The work extends beyond the front roof slope
• Volume allowances are exceeded
• Permitted development rights have been removed by an Article 4 direction

Building regulations always apply

Regardless of planning status, the conversion must meet building regulations covering structural stability, fire safety and escape, staircase design, insulation and ventilation. Your builder or architect will submit this for you.

Party wall agreements

If you share a wall with a neighbour and the work involves inserting beams into it or building up to it, you will normally need to serve a party wall notice, typically two months before work begins.