Legalising perimeter block housing

One of the paradoxes of planning reform that legalises the development of more housing in established urban areas is that it typically makes it easy to build like this:

While still making it difficult to build like traditional perimeter block housing like this:

Even from the Google Maps view, you can see that there are some important differences between the first built form, which is in Royal Oak, Auckland, and the second, which in Prague. The second approach provides a lot more housing, but also a lot more shared green space in the centre of the block. The first approach chops up footpaths with vehicle accessways and creates few opportunities for socialising in public spaces. And while aesthetics are subjective, I think most people would generally agree that the second approach results in a more attractive city.

So why do we get so much of the former and so little of the latter?

The answer lies with a well-intentioned planning rule with some unintended consequences: setback rules. As shown in the following diagram, residential zoning rules typically require buildings to be constructed a certain minimum distance from the sides of the lot, with additional ‘recession planes’ to constrain the upper storeys.

These are ubiquitous in contemporary residential zoning codes for a good reason: They prevent people from ‘building out’ their neighbours’ sunlight and privacy. From the perspective of managing externalities, or ‘spillovers’, in cities, setback rules are pretty reasonable.

But the unintended negative consequence is a less efficient and attractive built form. As Montreal-based traffic engineer Urban Kchoze discusses, traditional perimeter blocks are built incrementally, as residential neighbourhoods transition to a higher-density form. If it’s not possible to build out to the site boundaries, this process can never happen:

"[…] blocks such as this can be built progressively, they don’t need to spring up at once, building the blocs can be a matter of incremental development. But if that is true, then there must be transitional areas still around where we can see some buildings having been built up and some others haven’t. And indeed, looking at smaller cities, we can notice similarities between these blocs and blocs of smaller townhouses that are present in areas that were less central and less populated, and find areas where the two building forms coexist.

"The bloc’s basic design is already present, but some buildings are older, smaller, with only 2 stories, whereas buildings on the main avenue are deeper and taller, yet they have the same width, so can be built on the same lot.

"What this means is that it is very possible for areas to have begun full of attached single-family houses with 2 stories (or maybe even one, but they’re rare nowadays), only to be progressively built up, either by being replaced or by having floors added to existing buildings. Of course, this process didn’t need to come up all at once, which means that for a while, there would have been “pop-out” buildings taller than the rest, with walls built ready to welcome buildings of its own size later one."

So what is to be done? We can’t get rid of setback rules entirely, because they’re doing something useful, but keeping them in their current form isn’t a good idea either if we want a better city.

One suggestion would be to allow neighbours to waive setback rules on each other's properties, enabling 'reciprocal intensification'. This would effectively legalise the incremental development of perimeter block housing in New Zealand cities. While it wouldn’t guarantee that we’d get a better result, it would establish an option for waiving setback rules and building out to the site boundary.

This brings me on to one of the least-noticed but potentially most important parts of the Resource Law Amendment Act 2017, which was passed into law in April 2017. Section 87BA of the RLAA states that:

Boundary activities approved by neighbours on infringed boundaries are permitted activities

(1) A boundary activity is a permitted activity if—

(a) the person proposing to undertake the activity provides to the consent authority—

(i) a description of the activity; and

(ii) a plan (drawn to scale) of the site at which the activity is to occur, showing the height, shape, and location on the site of the proposed activity; and

(iii) the full name and address of each owner of the site; and

(iv) the full name and address of each owner of an allotment with an infringed boundary; and

(b) each owner of an allotment with an infringed boundary—

(i) gives written approval for the activity; and

(ii) signs the plan referred to in paragraph (a)(ii); and

(c) the consent authority notifies the person proposing to undertake the activity that the activity is a permitted activity.

For those of you (like me!) who find legal language difficult to interpret, the summary is: If your neighbour signs off on your plans to build out to the boundary, the council has to approve them, regardless of what it says in the planning rulebook.

Of course, as written, this doesn’t exactly provide for reciprocal intensification – ie your neighbour has no guarantee that you will approve their plans at a later date. But according to a lawyer friend, that can be addressed by placing a covenant on the property title that requires the owner of each property to approve their neighbour’s plans.

Overall, this a really useful law change that addresses one of the thorniest problems in urban planning. In an Act that is composed of a range of tweaks and fixes to a bewildering range of bureaucratic processes, this is a simple change that offers significant potential to make development easier and to get a better built form. It definitely deserves wider notice than it’s gotten to date. And - if anyone's looking for a clever business model that will make their city work better - how about going up and signing up neighbours for some reciprocal intensification?

A version of this article was originally posted on the Greater Auckland blog.