Draft NPPF: Viability, Certainty and the Limits of Standardisation

Viability has long been one of the most contested aspects of the planning system, often criticised for adding delay, uncertainty and imbalance to decision-making. The draft NPPF consultation tackles this issue directly, signalling a clear intention to reduce debate at application stage through greater standardisation and tighter expectations.

At its core, the proposed approach seeks to reinforce the principle that viability should be addressed primarily through plan-making, not negotiated afresh on a site-by-site basis. Standardised inputs, clearer assumptions and reduced scope for deviation are presented as mechanisms to increase certainty, improve transparency and, ultimately, support housing delivery. In principle, this direction of travel is difficult to oppose. While these principles are already well established in Planning Practice Guidance, the draft NPPF seeks to embed them more firmly within the national policy framework, reducing the scope for viability expectations to be treated as advisory or secondary considerations.

However, the challenge lies in how effectively this approach can be translated into practice. Viability is inherently sensitive to local market conditions, abnormal costs and timing. While plans can and should set clear expectations, there remains a risk that overly rigid assumptions fail to reflect the realities faced by individual schemes, particularly on complex or brownfield sites. If flexibility is constrained too tightly, viability may simply re-emerge as a point of friction elsewhere in the system.

For plan-makers, the draft NPPF raises the bar significantly. Plans will need to demonstrate not only that policies are aspirational, but that they are grounded in robust, up-to-date viability evidence capable of withstanding scrutiny over time. This places renewed emphasis on plan realism, monitoring and review, without which confidence in standardised assumptions will quickly erode.

For decision-takers, the implications are equally important. A system that genuinely resolves viability at plan stage should, in theory, reduce negotiation and speed up delivery. But this depends on the plan being sufficiently clear, current and credible. Where it is not, the risk is that decision-taking becomes constrained without the supporting evidence needed to justify that constraint.

The central question, therefore, is not whether viability reform is necessary, but whether the draft NPPF strikes the right balance between certainty and adaptability. If it does not, viability may continue to undermine delivery, not through protracted negotiations at application stage, but through plans that struggle to be implemented in practice.

Writer: Matt Hill, Planning Director