For developers working on sites between 0.5 and 1.0 hectares, a 9-dwelling scheme can unexpectedly trigger “major development” requirements – most notably, affordable housing.
The reason stems from the conflicting definitions across the planning system.
Here’s what you need to know and what it could mean for your project.
The procedural definition (DMPO)
The Development Management Procedure Order (DMPO) 2015 (as amended) governs how applications are processed – from validation and consultation requirements, to determining the statutory determination periods.
Under the DMPO, a residential site is “major” if:
- It provides 10 or more dwellings; or
- The site is 0.5 hectares or more and the number of units is unknown (e.g. outline applications)
So, a full planning application for 9 residential units on a 0.6ha site is not major development. It’s treated as “minor”, benefiting from an 8-week determination period.
The policy definition (NPPF)
The National Planning Policy Framework (2024) has a stricter definition. Here, “major” development means:
- 10 or more dwellings; or
- A site area of 0.5 hectares or more
Crucially, this doesn’t include the caveat “and the number of units is not known”. The result? The same 9-unit scheme on a 0.6ha site is “major” under the NPPF.
Why does this matter?
Paragraph 65 states that affordable housing should not be sought for developments that are not major developments – so your scheme may now be expected to contribute.
The Permission in Principle (PiP) definition
The PiP Regulations introduce yet another threshold to determine which sites are excluded from the PiP route. For residential schemes, “major” development is:
- 10 or more dwellings; or
- The site area exceeds 1 hectare
This means a 9-unit scheme on a 0.6ha site:
- Qualifies for PiP, but
- Is still “major” under the NPPF, bringing affordable housing obligations.
Similarly, 9-unit schemes on sites above 0.5ha in the Green Belt would also need to comply with the NPPF’s “Golden Rules”, as it would constitute “major” development through the NPPF definition, (Paragraph 156), including:
- 50% affordable housing
- Improvements to infrastructure
- Provision of green space
Viability quickly becomes a concern.
What are the options?
There are several strategic routes worth considering. For example, a PiP application can help secure a decision on the principle of development more quickly, with less technical information required up front – particularly relevant in ‘grey belt’ cases.
There may also be potential workarounds. Reviewing the site area to see if it can be reduced below 0.5ha could avoid the NPPF “major” threshold altogether.
A new ‘medium’ category on the horizon?
Further complications are coming. A revised NPPF is expected later in 2026, proposing a new “medium development” category:
- 10-49 dwellings, and
- Sites up to 2.5 hectares.
The aim is to streamline requirements for SME developers. Early indications suggest:
- Potential for financial contributions in lieu of on-site social and affordable housing
- Possible expansion of the PiP route to cover these schemes
However, the definition of “major” remains unchanged in the draft NPPF, meaning that “medium” may simply sit within it. Time will tell if this is revised in the version published to provide consistency with the other regulatory documents.
The bottom line
A scheme of 9-units or less on a site just over 0.5ha would fall into the category of “major development” under the NPPF definition, having potentially significant implications for policy requirements, affordable housing and viability.
How we can help
If you have a site within this size range, early strategy is key. We can advise on how to navigate these overlapping definitions and identify the most effective route to optimise the development potential.
