John Myers, co-founder of London YIMBY, argues that giving individual streets more say in local densification plans could make room for not only more housing, but more ambitious design and better streets

Infill is the easiest way for politicians to win votes and, with the support of existing residents, get millions more homes built, making best use of existing infrastructure and resulting in places that are walkable and attractive. But unlocking the needed scale and quality of infill requires improving the current system.

Among the ideas put forward in London YIMBY's recent report, Yes In My Back Yard: How to End the Housing Crisis, Boost the Economy and Win More Votes, the one that could prove most politically feasible and effective in getting homes built is to allow more infill to improve existing streets. Called ‘Better Streets’, this initiative could, over time, allow five million more homes in London alone, while making the city fairer, more liveable, more beautiful and more welcoming.

As part of 'Better Streets', we propose amending the law to allow an individual street to vote itself new permitted rights to extend and/or replace existing buildings, and to select a design code for the new façades to ensure they are acceptable to residents. The vote would require a double two-thirds majority – of current residents, and also of residents who have been there for at least three years, to prevent gaming of the system. Existing houses could be extended and subdivided, or replaced with taller terraced housing split into maisonettes. Individual plots could be combined to build mansion blocks of flats. There would be strict protections governing loss of light to houses not on the street, a limit on how far the new building could extend down the back garden, and specific rules for houses on street corners, and basement extensions.

Interviews conducted in research by London YIMBY suggest that allowing the street to vote on its own design code for façades is key in order to get people comfortable with the concept. Create Streets, a campaign to promote traditional streets, has shown how much people care about the appearance of new construction.

Of course, no homeowner would have to use the new permissions. They could just sit on them, team up with a small builder, or sell their home for a substantially increased value when the time is right for them. Over time, the new flats and terraced houses would create more homes for people to live in, making nearly everyone better off.

Affordable housing requirements are much more effective when they are fixed clearly in advance and incorporated in any price paid for the land. Contributions from the owner carrying out works could also be required for other infrastructure as needed – perhaps with an improved version of the Community Infrastructure Levy and Planning Gain.

Well-designed density

Half of the homes in London are in buildings of only one or two storeys, the same ratio applies in many other UK cities. Georgian and Victorian developments were often built far more densely and attractively than are current suburbs. The streets and squares of Bloomsbury and Pimlico accommodate five times as many homes per acre as a typical suburban street, and yet are also highly walkable and attractive.

Part of their success was enforcing a design code across the estate to ensure that builders took enough care. We could achieve much more today by copying some of the best practices of our predecessors, while avoiding their mistakes.

For example, many semi-detached plots in outer London were built within an easy walking or cycling distance of a tube station. The built square footage could be increased fivefold by replacing the current dwelling with a building line closer to the street, and extending up to the boundary lines at the side of the plot and a little further back into the garden, without encroaching on the light of the rear neighbours. This could even be done without loss of parking by including garage space into the design. The new buildings could be terraced houses and maisonettes, or mansion blocks spread over several plots.

There is plenty of land if only we use it better; the key is to do so in a way that the neighbours are happy about. Otherwise, politics will continue to create the same blockages that we currently see. Giving a whole street the same permitted development rights can, in areas of high demand, increase the value of each house by a factor of two or three. London YIMBY's surveys and focus groups suggest that, coupled with a design code, allowing decisions by individual streets would make residents much more willing to support improvements.

Though many people are happy with their current detached or semi-detached suburban houses, surveys undertaken by London YIMBY show they could often be even happier if given a way to improve their street with attractive, well-designed densification. Not every street will vote for it, of course, which is why a local consensus rather than imposed permitted development rights is so important.

Simplicity and ambition

We need to simplify the system to make planning permission a more straightforward process where projects have broad support. The Fitzroof project by HTA Design in 2010 added attractive mansard roof extensions on two terraces of Victorian houses on either side of the same street in Primrose Hill. Despite unanimity among the residents and widespread support from neighbours, it took two years and hundreds of pages of submissions to get permission. One individual involved described the experience as a ‘nightmare’.

The Fitzroof project is part of HTA's wider proposals of 'Supurbia', using creative ways to add much more housing on existing suburban plots, using the existing planning system. It is an important project, if in some ways too cautious. Because they are not conditional on agreement from the neighbours, the current proposals are deliberately designed to be unobtrusive and minimise opposition. With the support of a whole street, architects could be much more ambitious, as the Georgians and Victorians were.

Infill makes planning, architectural, urban design and economic sense. The challenge is to unlock more without a backlash. Bringing existing residents into the conversation, giving them greater power over their surroundings, and minimising unnecessary bureaucracy, can open up possibilities for ambitious designs that also create an attractive, more welcoming city.

FIND OUT MORE The London YIMBY campaign is one part of the rapidly-growing international YIMBY movement. Get in touch at londonyimby.org if you have ideas or constructive suggestions.

There is more on HTA's Supurbia study here.