top

Z Group

  /  Architecture   /  Permitted Development Rights for Upward Extensions to Commercial/Mixed Use Buildings
building permit

Permitted Development Rights for Upward Extensions to Commercial/Mixed Use Buildings

Along with the recent planning changes, you can now create flats in the form of a 2 storey upward extension to a detached commercial building without planning permission.

From 1st September, detached commercial or mixed-use buildings can benefit from a 2 storey upward extension for the creation of new dwelling houses and 1 storey for terrace buildings. For commercial properties, these will need to fall within the Use Classes of either A1 Shops, A2 Financial Services, A3 Restaurants and Cafes or B1(a) Office. Other uses also include pay day loan shops, betting offices and laundrettes.

If the property is mixed-use then it can consist of either two or more of the above listed uses or it may comprise of C3 dwelling houses along with at least one of those uses.

Under the new legislation, a detached building in commercial or mixed-use operation can extend upwards as follows:

Detached Buildings

The existing building must be;

  • Built between 1948 to 2018
  • In use as either A1/A2/A3, B1(a), betting office, pay day loan shop, launderette or a combination of these use classes or C3 along with one or more of those use classes on 5th March 2018
  • At least 3 storeys as existing
  • No taller than 30m once extended (not including plant)

The upward extension must;

  • Be used only as residential flats
  • Have internal floor to ceiling heights of each storey not exceeding 3m
  • Be a maximum of 2 storeys
  • Not exceed 7m above the existing building (not including height created by plant)

Terrace buildings in commercial or mixed use can now also be extended upwards.

Terrace Buildings

The existing building must be;

  • Built between 1948 to 2018
  • In in use as either A1/A2/A3 B1(a), betting office, pay day loan shop, launderette or a combination of these use classes or C3 along with one or more of those use classes on 5th March 2018
  • No taller than 18m once extended (not including plant)
  • Highest part of extended roof must not be more than 3.5m higher than every other building in the row of terraced buildings which it forms part.

For single storey terrace properties, the upward extension must;

  • Have internal floor to ceiling heights not exceeding 3m
  • Be a maximum of 1 storey
  • Not exceed 3.5m above the existing building (not including height created by plant)

For 2 or more storey terrace properties, the upward extension must;

  • Have internal floor to ceiling heights of each storey not exceeding 3m
  • Be a maximum of 2 storeys
  • Ensure the tallest part of the roof to the extension to not be more than 3.5m higher than any other roof along that terrace
  • Not exceed 7m above the existing building (not including height created by plant)

The permitted development right cannot be used to build on top of existing roof extensions.

The commercial/mixed use property must not be within article 2(3) land eg. a conservation area. Nor can it be within a site of special scientific interest.

The extension can only be added to the top of the “principal part of the existing building” which means you cannot extend a lower part of the property eg. if it consists of a tower and a podium/base – the extension cannot be added on the roof of the podium.

Whilst is a permitted development right, these extensions will still need Prior Approval from the Local Authority and as such planning officers will have to assess the proposal by making sure that it does not adversely impact neighbouring properties such as through loss of light/overshadowing, privacy and overlooking. The extension would also have to consider its impacts to the existing dwellings inside the building itself.

Similarly to other Prior Approval submissions, Local Authorities need to access its effects on the following:

  • Highways
  • Contamination
  • Flood Risk
  • Noise
  • Air traffic and defence asset impacts
  • External appearance
  • Access to adequate natural light
  • Protected views
  • Impacts of residential use in the area on the carrying on of business or trade.

Occupants of the property and adjoining neighbours will have to be notified and consulted of this Prior Approval and as such are given the opportunity to comment on the proposed works.

People have always been able apply to extend commercial and mixed-use properties upwards but through the longer and more expensive process of a Full Planning Application. Prior Approval cuts a lot of red tape but the extension can’t be given the go ahead unless the Local Authority are satisfied it will not harm neighbouring properties.

Other permitted works to facilitate these upward extensions:

The legislation allows for reasonable engineering works that required to achieve adequate structural stability to accommodate the additional floors. Works to replace existing or for the installation of new plant is permitted to facilitate the extension as well as provisions for appropriate and safe means of escape which could include additional external doors and staircases.

When does this come into effect?

These changes have been implemented on 31st August 2020.

How will this affect you?

If you own a low to mid rise detached commercial or mixed use property that was built between 1948 to 2018, then you could benefit from extending up to two storeys, bearing in mind – as explained above this will be subject to ensuring that the extension is designed appropriately and does not have an adverse impact on neighbouring properties and occupants of the existing building.

How can we help?

We have an expansive portfolio of extending properties both under permitted development and full planning applications – we can assist you in finding the best solution financially and in terms of design. We can help achieve this through feasibility studies and eventually through the submission of a Prior Approval application. Please contact us at planning@zgrp.co.uk or call at 0208 944 1180.

Write a Comment