Draft NPPF: Site Thresholds, Medium Development and the Limits of Categorisation

The draft NPPF consultation reflects a growing recognition that the long-standing distinction between minor and major development no longer captures how housing is delivered in practice. A significant proportion of new homes now come forward on schemes that are neither minor in scale nor strategic in nature, yet which are often subject to policy expectations designed for much larger developments.

The proposed introduction of a medium development category (10 to 49 homes inclusive on sites of up to 2.5 hectares) intended to address this mismatch. Annex C of the consultation document builds on this rationale by proposing clearer differentiation between small, medium and larger schemes, with the aim of applying policy requirements in a more proportionate and predictable way. In doing so, the government is seeking to reduce cliff-edge effects at existing thresholds and support delivery from a wider range of sites, particularly those that play an important role in urban areas and for SME builders.

The logic behind this approach is sound. Medium-scale sites, often delivering between small site thresholds and strategic allocations, make an important contribution to housing supply. Treating these schemes in the same way as large developments can introduce disproportionate cost, complexity and delay, undermining their deliverability.

However, the introduction of a medium category does not remove the underlying challenges associated with thresholds. Numerical cut-offs remain inherently blunt, and their effectiveness will depend heavily on how they are calibrated and applied. A medium threshold that works well in one market may constrain delivery in another, particularly where site sizes, land values and development economics vary significantly.

For plan-makers, Annex C reinforces the importance of aligning thresholds with local delivery patterns and evidence. If plans are to rely on medium-scale sites to meet housing needs, thresholds and associated policy expectations must be tested rigorously to ensure they support, rather than suppress, that supply.

For decision-takers, clearer categories may reduce argument, but they also risk hardening distinctions that are only loosely related to planning merit. Where schemes sit close to a threshold, outcomes may turn on categorisation rather than substance.

The key issue, therefore, is not whether introducing a medium category is helpful, but whether thresholds are being used as a tool to support delivery and proportionate decision-making, rather than as a substitute for judgement. How this plays out in practice will be critical to whether the reforms achieve their stated aims.

Writer: Ollie Cooper, Associate