Class CB: temporary buildings for a RAAC-affected school

Class CB is a time-limited permitted development right. Its existing 24th October 2026 expiry is being extended to 24th October 2028 by legislation taking effect on 21st October 2026.

It allows temporary buildings to be provided on school land where a school building has been vacated, wholly or partly, because reinforced autoclaved aerated concrete, usually called RAAC, has required the building to be taken out of use for health and safety reasons.

Class CB extension from 21st October 2026

SI 2026/1056, article 6, changes the three-year period in CB.1 to five years and the final expiry to 11.59 pm on 24th October 2028. The amendment takes effect on 21st October 2026, before the existing right would expire. The other limitations and conditions remain, including removal when the RAAC-affected buildings have been remediated or replaced if that requires earlier removal.

What Class CB allows

The combined floor space of the temporary buildings must not exceed 125% of the combined floor space of the parts of the RAAC-affected buildings that have been vacated.

The development must not increase the school’s published admission number. The temporary buildings must also be positioned, so far as practicable, to minimise the loss of playing fields and space used for parking or vehicle turning.

Height, siting and protected-site limits

• No temporary building may have more than 2 storeys
• No temporary building may exceed 9 metres in height
• No part of a temporary building may be within 5 metres of the boundary with adjoining residential land
• The right cannot be used where the school land covered by the building is or forms part of a SSSI, safety hazard area, military explosives storage area, scheduled monument or land within the curtilage of a scheduled monument

The school must notify the authorities

At the relevant time, the school must give written notification to the local planning authority. The notification includes the start date, school and contact address, floor-space figures, a written description, a plan showing the school land and development, and confirmation that the school has a RAAC-affected building.

A copy of the notification must also be sent to the relevant fire and rescue authority. Class CB is a notification right rather than a prior approval procedure.

Removal is mandatory

Under the pre-amendment wording, removal is required as soon as reasonably practicable after the RAAC-affected buildings have been remediated or replaced, or before 11:59 pm on 24th October 2026, whichever is sooner. From 21st October 2026, the amended CB.1 deadline moves to 11:59 pm on 24th October 2028 and the three-year period becomes five years. The earlier-removal requirement following remediation or replacement remains. The land used for the temporary buildings must then be restored as soon as reasonably practicable.

If temporary buildings are still needed after the Class CB expiry, Class CB will no longer provide planning permission and another planning route will be required.

Fees and appeals

Class CB uses a statutory notification rather than a planning application or prior approval process, so there is no Class CB application fee. If a different planning application is needed after Class CB expires or because the proposal falls outside the right, check the current charge on our planning fees page. A refusal of that planning application can normally be taken through the usual appeal process.

Relevant legislation

Class CB of Schedule 2, Part 4 of the GPDO contains the statutory wording for this permitted development right.

Explore Part 4

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Class CB RAAC School Buildings Page Updated: 1st October 2026