As housing need continues to outstrip supply across London, permitted development rights offer an increasingly valuable route for unlocking residential potential, particularly for underutilised or redundant buildings. A lesser-known but highly effective mechanism is Class ZA of the General Permitted Development Order (GPDO), which allows developers to create new homes with greater speed and design flexibility compared to traditional planning routes.
At BB Partnership, we’ve used this route to help clients realise residential value on constrained or complex sites, often in situations where a full planning application may have proved more difficult or less commercially viable.
To ensure we comply with policy requirements for these types of proposals, we always work with planning consultants to ensure compliance with the requirements.
Class ZA, introduced in 2020, allows for the demolition of certain commercial, light industrial, or residential buildings and their replacement with a new residential building, all under a streamlined Prior Approval process. It’s designed to support regeneration by enabling underused or obsolete buildings to be replaced with much-needed housing, without the lengthy timelines and uncertainty of a full planning application.
To qualify, the original building must:
The new residential development can be up to two storeys higher than the original building, with an overall height cap of 18 metres. While full planning permission is not required, local authorities still assess key issues including transport, flooding, design, and impact on neighbours as part of the Prior Approval process.
While Class ZA removes the need for full planning permission, it still requires a Prior Approval application. This means the local planning authority must assess a number of specific matters before work can begin, including:
This makes Class ZA a hybrid process: faster and simpler than full planning, but still subject to scrutiny. The quality and clarity of the submission are crucial.
Although Class ZA can be a powerful tool, it’s also complex, and many applications are refused due to avoidable issues, including unclear supporting information, insufficient justification on key impacts, or failure to demonstrate eligibility.
Here’s where a planning consultant adds real value:
1. Feasibility Assessment
Before committing time and resources, a planning consultant can assess whether your site and proposal are likely to qualify under Class ZA, helping you avoid pursuing an unviable project.
2. Robust Supporting Statements
One of the key elements of Prior Approval is the submission of well-structured supporting documentation. A planning consultant will prepare a Planning Statement that addresses each of the relevant criteria and provides the evidence planners are looking for.
3. Coordination of Specialists
Many Class ZA applications need input from other professionals, such as transport engineers, flood risk consultants, and heritage specialists. A planning consultant can coordinate these inputs to ensure a cohesive and compliant submission.
4. Monitoring and Follow-Up
Responding to local authority questions, though it’s vital to remember: these applications either comply or they don’t. A local authority cannot approve a scheme that almost complies.
Our redevelopment of 82–84 Mitcham Lane exemplifies how Class ZA can be strategically combined with conventional planning routes to unlock a site’s full potential.
Phase 1 involved demolishing a disused warehouse behind the site and replacing it with a high-quality nine-unit residential scheme. This phase was delivered under Class ZA and featured:
Phase 2 was a full planning application for the Victorian villas fronting the high street. This retained the historic façade and delivered:
This two-pronged approach allowed us to deliver 17 new homes with no affordable housing contributions while sensitively enhancing the urban fabric of the Mitcham Lane Local Centre.
Class ZA offers advantages for developers:
However, the process is not without challenges. Prior Approval applications can be refused if supporting evidence is lacking or design quality is poor. That’s why at BB Partnership we work closely with planning consultants, heritage specialists, and other consultants from the outset to ensure a robust and coordinated approach.
Key Point: You must comply 100% with the relevant criteria. Unlike full applications, Prior Approval gives no room for negotiation. A local authority cannot approve a scheme that “nearly complies.”
At BB Partnership, we understand how to leverage permitted development to maximise value, reduce planning risk, and unlock the full potential of every site. Our collaborative, strategy-led approach, working closely with planning consultants and other specialists, ensures that even the most challenging sites can become successful residential projects.
Get in touch to explore how we can help you unlock your site’s potential through Class ZA or a tailored planning strategy.
BA [Hons], Dip Arc, RIBA
Director
BA [Hons], Dip Arc, RIBA
Director
BA [Hons], Dip Arc, RIBA
Director