On March 25th, New London Architecture’s Coffee Conversation brought together a cross section of voices from architecture, planning, development and policy to discuss one of the most urgent questions facing London today: how can small and difficult urban sites make a meaningful contribution to our housing crisis?

RDA Architects has been working on constrained, complex, “impossible” sites for over 30 years, so this is a debate we care about deeply. Our thanks to NLA for convening the conversation and for inviting Richard Dudzicki to speak on a topic that has been central to our practice since the 1990s.

What emerged from the session was clear: the future of housing delivery cannot rely on large strategic sites alone.

National government continues to pursue ambitious housing targets, often cited as 300,000 homes a year across England, yet actual delivery consistently falls short. In London, the London Plan identifies a need for around 52,000 new homes per year, while completions struggle to keep pace, hovering closer to the 30-40,000 mark in many recent years.

The Prime Minister’s recent announcements and the latest budget reiterate the political focus on “unlocking land” and “cutting red tape”. But most of the public narrative still gravitates towards large strategic sites, major regeneration areas and new settlement proposals.

The reality on the ground is different.

Across London, some of the most immediate and transformative opportunities are already hiding in plain sight, within the existing urban fabric:

• Former garage courts and yard spaces 

• Backland plots and infill gaps 

• Fragments of brownfield land 

• Redundant commercial premises and service yards 

• Awkward slivers between established buildings

These small, difficult sites are not marginal. Taken together, they represent one of the most significant, and least effectively tapped, sources of housing capacity in the city.

The question is not whether these sites exist.

The question is whether our policy, planning and design frameworks are agile enough to unlock them.

One of the strongest messages from both the NLA conversation and wider research is that small sites are often forced through a system designed for large schemes.

Research by Lichfields in collaboration with Pocket Living, examining 60 small residential developments across London, found that 98% took longer than the statutory 13 week determination period, with average times stretching to more than four times the intended timeframe. This is not a minor administrative issue.

For SME developers and specialist delivery partners, time is viability. Unlike volume housebuilders spreading risk across multiple schemes, smaller players typically carry:

• Higher equity exposure on each site 

• Tighter financing conditions 

• Less capacity to absorb prolonged uncertainty.

Every extra week in planning means more interest, more risk and delayed delivery. As Pocket Living’s Marc Vlessing put it, for small developers “time is the enemy.”

Behind this sits a deeper misconception: that applying the same layered planning obligations to a 20 home infill scheme and a 300 home regeneration project represents fairness and consistency.

In practice, this “one size fits all” approach often creates the opposite:

• Disproportionate burdens on constrained plots 

• Complex affordable housing negotiations on marginal schemes 

• Heavy viability and transport requirements on sites with limited capacity 

• A cumulative layering of standards that simply does not reflect the realities of tight urban footprints

Small does not mean simple. In many cases, small actually means more complex and our policies need to recognise that.

One of the more encouraging themes from the NLA Coffee Conversation is that policy is beginning to catch up with what architects, planners and SME developers have known for years: small sites are central to housing delivery, not peripheral to it.

The Greater London Authority has made this increasingly explicit, particularly through London Plan Policy H2 (Small Sites) and related guidance. As City Hall states, “small sites should play a much greater role in housing delivery”.

Key shifts include:

• A clear expectation that sub 0.25ha sites contribute substantially more to borough wide housing targets. 

• Support for area wide design codes and more proactive identification of small site capacity. 

• Recognition that small sites can and should play a significant role in brownfield, context sensitive growth.

Most importantly, the GLA’s small site design codes challenge a long held myth in planning culture: that small, fragmented sites are too awkward to deliver meaningful numbers of homes.

In reality, policy is now edging towards the opposite conclusion.

Properly supported, small sites are one of the fastest ways to deliver well designed, climate conscious homes within existing neighbourhoods.  This shifts the conversation from “Do small sites matter?” to “How do we actually unlock them?” That is where architectural leadership becomes critical.

A particularly valuable strand of the NLA discussion was the move away from seeing small sites as mere tick‑boxes towards housing targets, and towards their urban design value.

Handled well, small sites can:

· Repair broken streetscapes and awkward edges 

· Activate dead frontages and underused corners 

· Increase density in a fine‑grained, neighbourly way 

· Support local high streets, public transport and social infrastructure 

· Allow neighbourhoods to evolve incrementally rather than via one‑off, disruptive mega‑schemes.

With careful design, they can deliver high-quality homes in places where people already want to live. This is a form of incremental urbanism that respects the grain of the city.

From a design perspective, small difficult sites demand some of the most rigorous thinking:

· Access and servicing in tight conditions 

· Rights to light and neighbouring amenity 

· Overlooking, privacy and acoustic control 

· Level changes, existing structures and complex boundaries

This is where the constraints of a site can drive genuine innovation. Some of the most inventive and contextually sensitive housing we have produced as a city has come from exactly these kinds of plots.