Upwards extensions: new permitted development right to come into force on 1 August

09 Jul 2020

What is proposed to be permitted?

The construction of up to two additional storeys of new flats immediately above the existing topmost residential storey on a building which is a purpose-built, detached block of flats.
Some associated works are also permitted, explained further below.

Which properties are eligible?

This permitted development right only applies to purpose-built detached blocks of flats (i.e. built as and remaining as a block of flats) which:
  • Did not obtain their residential use through other permitted development rights
  • Do not have any other uses (e.g. commercial ground floor)
  • Were constructed between 2 July 1948 and 5 March 2018
  • At above ground level, have three or more storeys
  • Are not located in or forming part of any of the following sensitive places:
    • Conservation Areas
    • AONBs
    • Specified areas for protection of natural beauty
    • The Broads
    • National Parks
    • World Heritage Sites
    • SSSIs
    • Listed buildings or land in its curtilage
    • Scheduled monuments or land in its curtilage
    • Safety hazard areas
    • Military explosives storage areas or
    • Land within 3km of the perimeter of an aerodrome

It should be noted that permitted development rights can be removed by existing planning conditions or Article 4 directions, so this will also need to be checked in respect of each building.

Restrictions on size

The additional extension must be to the principal part of the building.
Only two additional storeys are permitted.
There are various restrictions on the size of the upwards extension, including:
  • The extended building cannot become higher than 30m;
  • The floor to ceiling height of any additional storey cannot be more than 3m high or more than the floor to ceiling height of any of the existing storeys (whichever is the lesser, measured internally)
  • The overall height of the roof of the existing building cannot be greater than 7m higher than the highest part of the existing roof

Other works

The permitted development right also grants any or all of the following:
  • Engineering operations reasonably necessary to construct the additional storeys and new flats (provided that these are within the curtilage of the existing building and are to strengthen existing walls or foundations or install/replace utilities services, but visible support structures cannot be on or attached to the exterior of the building)
  • Works for the replacement of existing plant or installation of additional plant reasonably necessary to service the new flats (subject to there having already been plant on the existing roof and to size restrictions)
  • Works for the construction of safe access/egress including fire escapes etc (provided that these are within the curtilage of the existing building)
  • Works for the construction of storage, waste or other ancillary facilities reasonably necessary to support the flats (provided that these are within the curtilage of the existing building and subject to restrictions on their location)


An application must be made to the local planning authority for prior approval in respect of the following issues:
  • Transport and highways impacts
  • Air traffic and defence asset impacts
  • Contamination risks
  • Flooding risks
  • External appearance
  • The provision of adequate natural light in all habitable rooms of the new flats (this is something the Government is newly concerned about, as they have applied it to other permitted development rights which allow the creation of dwellings)
  • Impact on amenity of the existing building and neighbouring premises
  • Whether the siting of the building will impact on a protected view (London-centric)

If all of these matters are approved and prior approval is granted, there will be three years to complete the development.
If prior approval is refused, an appeal can be made to the Planning Inspectorate.

Community Infrastructure Levy

The Community Infrastructure Levy is a developer contribution chargeable on the creation of new floorspace by the square metre.
Developers should be aware that the new flats created by this permitted development right will attract the payment of Community Infrastructure Levy charges.  The cost varies between authorities and within London Mayoral CIL is to be paid additionally.

Further reading

Destination: office?

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Emily Wood considers the results of our recent survey and the implications for the future of the post-pandemic workplace
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Commercial lease renewals and pandemic clauses

Will commercial reality trump the law when leases are up for renewal? Property expert James Picknell takes a look
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Permitted Development Rights and the revised NPPF: Article 4 directions

Blog, Legal Updates
A revised National Planning Policy Framework has just been published. Holly Stevenson focuses on the change to Article 4 Directions
Read more Read

Can commercial lessees now ‘relax’ given the extended Government moratorium on forfeiture for non payment of rent?

Legal Updates
Property Litigation Partner, Keith Pearlman, doesn't think so and explains why they could be in for a nasty shock from 1 October of this year
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