Loft conversion planning permission in Berkshire

Permitted development: the limits

Most houses in England have permitted development rights, which allow some building work without a planning application. For loft conversions, the rules are in Class B (roof enlargements such as dormers) and Class C (other roof alterations such as rooflights) of the General Permitted Development Order. A roof enlargement is allowed without planning permission only if:

• it adds no more than 40m³ of roof space to a terraced house, or 50m³ to a semi-detached or detached house, counting any earlier roof extensions;
• no part is higher than the highest part of the existing roof;
• no part extends beyond the existing roof slope on the front of the house where it faces a road;
• it has no verandah, balcony or raised platform, and no new or altered chimney, flue or soil and vent pipe;
• the materials look similar to the rest of the house;
• except for hip-to-gable conversions, the eaves are kept and the enlargement is set back, as far as practicable, at least 20cm from the eaves, measured up the roof slope;
• it does not stick out beyond the outside walls of the original house;
• any window on a side wall or side roof slope is obscure-glazed and does not open below 1.7m from the floor.

Rooflights fall under Class C: they must not stick out more than 15cm from the roof slope or rise above the highest part of the roof, and side rooflights must be obscure-glazed and non-opening below 1.7m.

Summarised from the legislation (Class B, Class C). The GOV.UK technical guidance explains each rule with diagrams.

When you need planning permission

• Conservation areas. The roof enlargement right (Class B) does not apply in conservation areas, so a dormer, hip-to-gable or mansard there needs planning permission. The rooflight right (Class C) is not excluded.
• Article 4 directions. A council can remove permitted development rights on particular streets. Reading has 15 such directions (see below).
• Flats and maisonettes. Householder permitted development rights do not apply to flats.
• Beyond the limits. A bigger volume, a raised ridge, a front dormer facing the road or a balcony all need a planning application.
• Homes created under other permitted development rights, such as commercial buildings or farm buildings converted to homes, and new homes built under Part 20 of the Order.

A householder planning application in England costs £548 (from 1 April 2026). The statutory time limit for deciding it is 8 weeks (GOV.UK), so allow for that before your build date.

Lawful development certificates

If you think your loft conversion is permitted development, you can ask your council for a lawful development certificate for a proposed development. It is optional, but it gives you written confirmation that the work is lawful, which can help when you come to sell. It costs £274, half the householder planning fee (GOV.UK).

The 10 year rule

If building work that needed planning permission goes ahead without it, the council can take enforcement action within a time limit. Since 25 April 2024, that limit in England is 10 years for building work substantially completed on or after that date. Work substantially completed before 25 April 2024 keeps the old 4-year limit (GOV.UK). This is not a reason to skip permission: unauthorised work can cause problems when you sell, and building regulations are a separate requirement.

Planning is not building regulations

Even when you don't need planning permission, every loft conversion needs building regulations approval, covering structure, fire safety, stairs and insulation. Read our building regulations guide.

Planning in each Berkshire council

Your council depends on your address, not your postcode or nearest town: Earley and Woodley, for example, are in Wokingham Borough, and parts of Tilehurst are in West Berkshire. Find your council on GOV.UK.