Adding Extra Storeys - PDRs

Permitted Development Rights - Extending Upwards



New Permitted Development Rights For Adding Extra Storeys


New Permitted Development Rights (known as Use Class ‘AA’) mean you can now add extra storeys to most houses without making a full planning application.

But you can’t just go ahead and start building. First you have to apply for ‘Prior Approval’ to your Local Planning Authority.  Like making a mini planning application, this involves submitting a written description together with drawings of the proposed elevations showing the positions of the windows etc.

The Planners will then consult neighbours and consider factors such as the impact on adjoining properties – ie overlooking, privacy and over-shadowing etc.


Use Class AA  – ‘Enlargement of a dwellinghouse by construction of additional storeys’

You can now add up to 2 new storeys onto existing houses (of 2 or more storeys high). For bungalows you can add 1 extra storey.   Use Class AD permits the extra storeys to be used as flats in some cases.



            Conservations areas or heritage sites etc

            Listed Buildings

            Homes converted from offices or a Change of Use

            Buildings containing flats

           Properties built before 1st July 1948 or after 28th October 2018

            Where PD Rights have already been removed by a planning conditions, or in the local area by what’s known as an ‘Article 4  Direction’.



  Max height you can extend by
Detached Bungalows 3.5 metres
Detached Houses 7 metres
Semis & terraces 3.5 metres above next door – OR above the highest part of the terrace


  • The maximum height relates to the very highest part of the roof externally, usually the ridge.
  • Your new rooms can’t have larger floor-to-ceiling heights that in the existing house, up to a maximum of 3 metres.
  • You can only extend the ‘principle part’ of the house upwards
  • Materials must be of similar appearance to the existing house
  • No new windows on side elevations & roofs
  • The roof must be the same pitch as the existing roof.
  • The enlarged property can only use as a C3 dwelling house (not C4 HMOs).
  • Building Control will need to approve full design details including safe access and escape from fire.


This is a useful table showing ‘airspace opportunities’ which apply to different types of property.




Use Class AB  

Similar to AA, this allows you to add up to two storeys above terraced or semi-detached commercial buildings – shops and offices –  including those with flats above them.

Use Class AC

This relates to the design details for structural support, such as strengthening existing walls.

Use Class AD  

This relates to additional flats on top of existing detached houses (see also Use Class AA above).


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