Forget The Greenbelt; YIMBYs Should Focus On Permitted Development

Britain needs housing, and we all know who is to blame for our lack of supply: those dastardly NIMBYs and their unenlightened self interest in keeping property prices high.

Or maybe that's not really what's going on. Most people agree that we need more homes. When you look at most opposition to new housing, a pattern emerges -- most opposition to housebuilding is opposition to concreting fields with deanoboxes, not to adding new homes. In fact, the only organised and large scale opposition tends to be over greenfield development. There's no Council for the Protection of Urban England pushing to keep brownfield land as brownfield. Brits like their green and pleasant land and wish to keep it; they aren't usually so bothered by a couple of houses being built on a garden.

And who can blame them? The costs of greenfield development, both aesthetically (loss of visual appeal replaced by boxes on concrete) and logistically (increased demand on infrastructure) fall on existing residents, whilst the benefits primarily flow to the landowners and developers. Compare this to adding a backyard rental cottage: the primary beneficiary of the development is the same person who bears most of the costs, so there is less incentive to oppose it, and the cottage would be tucked away where it would not detract from the visual appeal of the area.

The government expanded permitted development quite a lot in 2020 with little pushback, enabling the owners of houses built between 1948 and 2018 to add additional storeys to their homes -- and these additional storeys can include flats. Expanding permitted development rights therefore seems to be a politically feasible route to go down -- whilst the standard development pattern benefits landowners at the expense of homeowners, permitted development rights benefit homeowners. Certain options in particular would benefit homeowners with larger houses, who tend to be older voters that the government wishes to keep onside.

There are a couple of suggestions that would be natural extensions on existing policy. First, the right to add a mansard roof to any property not in a conservation are. At present there is a right to add ugly dormers to most houses, regardless of their age, and to add a whole floor to many of them. A Mansard roof would be far more aesthetically pleasing than what is already allowed, and is significantly cheaper to construct than a full additional storey. This would enable many presently small homes, that are amongst the cheapest of properties for those wishing to get on the property ladder, to become family homes.

Secondly, the right to add an annexe; or as they are usually called by urbanists and planners, an Accessory Dwelling Unit (ADU).

Adding accessory dwellings could have significant impact on rents. In addition, as many of the houses that would be suitable for this are owned by pensioners, this would provide an source of income to supplement pensions. With an increasing supply of rental properties available, there would be reduced pressure on existing homes, which would return to the market for would-be homeowners to purchase. This is not as radical as it might seem; the right is already present if the additional unit is added on top of the existing house, it just needs to be extended to include other extensions such as outbuildings.

The Cameron government introduced a rent a room scheme to try and take advantage of an oversupply of housing. This is a good direction, but many people do not wish to share their homes with strangers. If part of the home can be carved out into an ADU and reted out, however, that would present a very different proposition that would likely see more uptake.

Permitted development is not unrestricted development, and there's no reason ADUs would be. Reasonable restrictions could be: no more than fifty square metres, no more than two tenants (most households are one or two person), and perhaps councils having the power to require a parking space.

Politics are not aligned right to straight up abolish the Town And Country Planning Act, and doing so would most likely result in a vast expanse of poor quality homes and neighbourhoods in any case, as seventy-five years of planning restrictions have warped housebuilding and it would not change back immediately. But politics *are* aligned right to chip away at it within existing neighbourhoods. Choose your battles carefully if you wish to win.

EDIT: I realised sometime after posting this that there's a good chance most annexes would *not* be rented out -- because of household demographics, many 1-2 person households are older owner-occupiers who may choose to downsize to a backyard cottage to either rent out their main house or permit their children to live there. Either way though, housing supply increases.