The recent change to the law regarding permitted development (Class MA), now allows floorspace greater than 1500sqm to be converted to residential uses via the Class MA mechanism. Reuse and retrofit of our existing building stock should be a common approach where possible and indeed is the policy stance being adopted by local authorities and building stakeholders alike. There is strategic advantage to be had by believing in ‘retro-first’.  

Crucial concerns over the quality of resultant residential accommodation coming forward under PD are addressed through the requirement for greater technical compliance – LPAs now require PD development to meet space standards, have adequate daylight and be assessed for fire safety, noise and transport impact.  

A more rigorous technical requirement to demonstrate the quality of a PD proposal shouldn’t be seen as a barrier to development, but rather an opportunity to realise quality and value. Done right, PD can help alleviate two problems – vacant assets and housing need. Done exceptionally, it can drive higher values in sought-after locations or in architecturally unique spaces.  

On our Westminster project, One Bessborough Gardens, DLG’s approach has been to look at this exercise of conversion from office to residential via parallel design workflows:   

  • what can be achieved within the scope of a Class MA application, without making external changes? 
  • and what additional value, quality and efficiency can be driven through a subsequent, more invasive retrofit approach?  

This resulted in a two-phase Planning strategy – a Class MA consent, establishing the principle of residential use, to be followed by detailed submission for upward extension, new roof terraces, new entrances, repositioned windows and a more efficient building servicing strategy.  

On another project in west London, we have explored options for office and residential options within the existing and an extended footprint within an imposing historic building. A Class MA proposal for studio apartments within the existing building envelope has the potential to then be ‘upgraded’ via a full planning consent, adding rear and rooftop extensions to form split-level front-to-back apartments and penthouses.  


Extended envelope - Workspace use.
Extended envelope - Residential use.

Designing in parallel, we can prove a site’s potential via the lesser-risk Class MA route, whilst exploring the enhanced value a future, full-planning approach may offer – with the opportunity to avoid repetition and time at the early design stages and assist initial assessments for funding, procurement, value and budgets.  

A full planning approach then introduces the potential for new building services, delivering lower operational carbon usage; better planned homes; improved thermal efficiency; more attractive facades; roof terraces and external amenity – all of these complete the picture of how retrofit and reuse can deliver outstanding new uses for our existing buildings across the UK.  

Residential use - extended footprint.