Shifting the dial for small sites

T wo years ago, after many years in architectural practice, Alex Somerville and I left to set up Oddment, a development enterprise with a particular focus on small sites. The move came from a growing frustration with the limits of traditional practice. 

 

Progress was not immediate. Alongside running small studios and teaching, we spent evenings and weekends looking for sites, testing their capacity and learning how development finance works. 

Our breakthrough came in Lewisham, where we acquired a small backland site at auction in May 2024. It had been refused twice before and was easy to overlook. But we felt there was a more thoughtful route through the planning process. The scheme, which now has planning permission and will start on site shortly, delivers two family homes on a constrained site formed from the consolidation of rear gardens. It is a small project, but one that turns a forgotten piece of land into something useful and well considered.

 

Yet the scheme took 14 months to receive planning permission, despite its scale and clear alignment with policy. This points to a wider tension. On the one hand, policy is increasingly supportive of small sites. The London Plan and many local authorities recognise that smaller developments have an important role to play in meeting housing targets. On the other hand, the systems needed to deliver this ambition remain under strain.

 

For small, self-funded developers, extended planning timelines introduce risk. They increase costs, tie up capital and make it harder to move on to the next project. A 14-month determination period for two houses is not just inefficient, it is prohibitive. When this is repeated across multiple sites, the impact on delivery becomes significant.

Recent changes to the National Planning Policy Framework signal a decisive shift towards speed of delivery that is already having an influence on decision-making in the planning system. 

The reintroduction of mandatory housing targets, the strengthening of the presumption in favour of sustainable development, a renewed emphasis on maintaining a robust five-year housing land supply and the introduction of the “grey belt” concept and continued prioritisation of brownfield land will bring forward a wider range of sites, including smaller and more marginal plots that have historically struggled to gain support.

 

In theory, these reforms should create a more supportive and predictable environment for small sites and smaller-scale developments, with greater opportunities arising from housing need and policy pressure. The continued decline of small- and medium-sized housebuilders has created a clear gap in the market. Larger developers tend to focus on scale, which often leaves smaller and more complex sites overlooked. For those willing to engage with them, this creates a genuine opportunity.

 

But in practice, a gap is likely to remain between policy ambition and delivery on the ground. Despite policy support in principle, small site applications are still subject to lengthy and often unpredictable determination periods. For projects working with tight margins, time is not just frustrating, it’s a real risk that can quickly undermine viability. Local authority capacity constraints, continued reliance on case-by-case interpretation, and the financial realities of bringing forward small, often constrained sites mean that many of the structural barriers to delivery are not fully resolved.

 

At the same time, the cumulative weight of regulation continues to increase. Requirements around biodiversity, affordable housing and technical compliance are all important, but they are not always easy to reconcile with the realities of small scale development. Rising construction costs add further pressure, narrowing margins and increasing exposure at every stage. What emerges is a landscape defined by both opportunity and friction.

 

 

At a regional level, we welcome the news that the New London Plan will provide a design guide tailored for small sites. At present, guidance varies significantly between boroughs, which increases risk and makes it harder to assess opportunities with confidence. A more consistent framework will help to ensure that good schemes are recognised and supported across London.

 

Notwithstanding the emerging planning reforms, there remains a need for greater clarity on the following issues, which continue to have a significant impact on planning and programme risk for small sites.

 

Although its importance is unequivocal, affordable housing policy is frequently applied inconsistently, is complex to navigate, and has a disproportionate impact on small sites. The introduction of a clear London-wide threshold, supported by a graduated contribution framework and fixed payments in lieu of viability negotiations, would reduce uncertainty, expedite delivery, and enhance site viability.

 

Planning committees are another source of planning and programme risk. Often well considered, policy compliant schemes are called in, as our site was in Lewisham, introducing delay and unpredictability. At the moment, each borough has its own approach to what triggers a committee. A more consistent London-wide approach which prioritises policy alignment and officer judgement over volume of objections, would better recognise high-quality design, reduce demands on council resources, and strengthen developer confidence.

 

Biodiversity Net Gain (BNG) continues to present challenges for small sites. While its environmental objectives are recognised and supported, its current application is disproportionate for small sites, introducing cost, complexity, and delay. There is growing indication that refinements to how BNG applies to smaller developments may be under consideration, and the sector awaits clarity on whether and when these changes will be formalised. Establishing a clear threshold below which BNG is not required would help support delivery and biodiversity enhancements should instead be secured through simpler, more proportionate mechanisms that avoid the need for complex and time-consuming legal agreements.

 

Despite these constraints, we’re optimistic about the future. Small sites invite careful, inventive thinking and enable a level of experimentation and ambition often difficult to achieve on larger schemes. Our second site in Ealing reflects this. Acquired through the GLA Small Sites Small Builders Programme, it replaces underused garages with four family homes, constructed using an innovative timber cassette system. It is a small scheme, but one that shows how carefully considered design and modern methods of construction can deliver high quality homes while driving new ideas around material, form and sustainability.

 

Opportunities like this point towards a more diverse development landscape, with a greater role for smaller, design-led practices. But for that potential to be realised, policy ambition must be matched by meaningful change. Scattered across towns and cities, from rear gardens and infill plots to disused garages and leftover fragments of land, small sites offer a form of gentle density that is more adaptable, less disruptive and more closely tied to local context than their larger counterparts. Policy is starting to reflect this. With the right support, small sites can play a far greater role in shaping the future of housing.