Intensification and how to achieve it

Above: backyard development behind an existing historic home in Austin TX. By my friends at Thoughtbarn.

There’s been talk this week, following the FT reporting that cities can’t deliver to the government’s proposed ‘urban uplift’ housing targets, about whether this is a genuine complaint or simply a lack of imagination. Some pointed to the potential to intensify existing urban areas with low-density homes as a way to provide plenty of new homes without needing either brownfield or greenfield land. And it’s true that we have lots of areas that were once suburbs but are now central in towns and cities, with great access to jobs, transport and local services, still formed of individual homes on big plots. If we want to avoid unnecessary greenfield development and to reduce car use, it's perverse to say that these areas should remain unchanged.

Intensification, in some forms, is common practice. People buy bungalows or small homes in good locations and rebuild them into far bigger houses. The case studies of 'successful' intensification on a street-wide scale (South Tottenham/Stamford Hill, Primrose Hill) are also examples of allowing existing homes to become bigger - not of knocking them down and rebuilding them altogether. But neither of these approaches helps with the housing shortage.

More comprehensive forms of intensification are also already possible without any new legislation. A developer is perfectly at liberty to approach the residents of a suitable street, buy plots, apply for planning permission to redevelop, and replace them with more homes in a denser arrangement. Planners are open to this in most areas, because the sustainability benefits are so clear. But there are only a scattering of these schemes that come forward, because it’s too difficult to find adjacent plots where the owners want to sell up at the same time, and the viability can be borderline.

If we are going to intensify low-density neighbourhoods, we need to look at solutions that can be implemented by individual plot owners, and not solutions that need multiple plots. Stateside, in many places, backyard development of additional homes is permitted on the plots of existing houses . This is what in the UK we often call ‘tandem’ development and, historically, planning regulations have frowned on it. This should be changed, because it has many advantages that make it a deliverable form of intensification.

Firstly, it can be done on single plots without needing to consolidate multiple plots into a single ownership. No property purchase is required, massively improving viability. Secondly, it can be undertaken by the property owner themselves – who retain control. No-one is forced to redevelop. The owners can stay in their original home, and can sell or rent the additional unit(s) themselves, to people they are happy to live alongside. Thirdly, it has fewer neighbour impacts than developing small apartment buildings across multiple plots. The street scene remains unchanged. Parking can be dealt with on-plot and new homes design-coded to avoid overlooking neighbouring homes or gardens. Croydon’s Suburban Design Guide is a good example of creating a code for on-plot intensification, although its continued insistence that tandem development be ‘subservient’ –lower and smaller than the ‘host’ dwelling – is retrograde. There are good examples where bigger buildings can be developed behind lower existing homes – have a look at Thoughtbarn’s fourplexes in Austin, Texas.

Another simple policy change would be (in accessible urban locations) to refuse applications to replace a single home with a larger single home, or for major (non PD) extensions, unless an additional home would also be created on the plot. This would change the market for under-developed plots from aspirational wealthy homeowners, to small builder-developers creating more affordable units. Historically we’ve disliked the subdivision of family homes into flats, because of prejudice against lower-income households in ‘family’ areas. The HMO use class remains a stain on our planning system and should be abolished (that’s a matter for another article), but policy should be encouraging subdivision of homes into good quality, self-contained (non HMO) flats or maisonettes, compliant with high design standards all around, including garden/balcony space for all homes and conditional on energy efficiency improvements. 

While none of this would result in ‘affordable’ (as technically defined) housing, it would create smaller and therefore cheaper homes, and it would be likely that a proportion would be privately rented. This would help the ‘squeezed middle’ and first-time buyers - exactly the target demographic that the government says it wants to support. And these policy changes could be easily implemented without the over-complicated and frankly weird system proposed by the Street Votes paper. Croydon’s design guide shows that the planning and design side can be led by local authorities with appropriate local consultation, rather than expecting residents themselves to self-organise – which is too slow and patchy. The main issue is – as always in housing – not policy but delivery.

To achieve intensification at meaningful scale needs financing and a concerted marketing campaign targeting property owners in these kinds of streets. Most people see planning and building as what it is – a massive hassle and very expensive. If a turnkey solution, combining financing, planning, design and a slate of pre-approved contractors, was offered to homeowners, there could be a step-change in the speed and amount of intensification that takes place.

Intensification really could help increase housebuilding rates without using greenfield land, but only if government accelerates this with funding. Local authorities could bid for funds to deliver intensification programmes that combine marketing, design, planning and affordable loans to cover construction costs. This would generate local jobs, address local housing need, and financially benefit individual local homeowners, not deep-pocketed developers. If just 0.5% of Bristol's homeowners subdivided their house, or created an additional home on their plot each year, this would meet nearly all the council's 'uplifted' housing target. If government is serious about urban rather than greenfield development, funding intensification would be a win with political appeal all round.