What Can Hives and Barnacles Teach Us About Solving a Housing Crisis?
There is a lot that modern cities, with formal, bureaucratic governing structures and land-use regulations, can learn from pre-modern cities and their informal attributes. This is one of the crucial themes in urban planner and designer Patrick Condon's book 5 Rules for Tomorrow's Cities: Design in an Age of Urban Migration, Demographic Change, and a Disappearing Middle Class, published by Island Press. We need to view cities as the complex, adaptive systems they are—and when we do, we gain insight into how to address today's pressing challenges.
Take the housing crisis in Condon's home city of Vancouver, BC. (Or just about any high-cost city in North America.) There are reasons to suspect that a policy of "just build more" is, by itself, insufficient to deal with the complex dynamics of high housing costs out of proportion to local incomes. In this excerpt, Condon proposes we take a lesson from how traditional cities expand their housing stock to meet their needs....
...And perhaps a couple of valuable metaphors from the animal world as well. Meet “hiving” and “barnacling,” two underrated strategies for incremental but scalable growth. — Strong Towns staff
Hives and Barnacles as Human Habitat
(The below excerpted with permission from Five Rules for Tomorrow’s Cities: Design in an Age of Urban Migration, Demographic Change, and a Disappearing Middle Class by Patrick Condon. Copyright © 2019 by Patrick Condon. Reproduced by permission of Island Press, Washington, D.C. )
Most buildings (in both the developed and undeveloped world) are relatively small. Small buildings can often be added to by “barnacle-ing,” that is, attaching pieces to the sides or top of an existing structure, as the need arises. Vancouver has many examples of barnacle-ing, prompted by policy changes that allowed additional density in exchange for retaining the existing structure. In some cases the habitable square footage on the parcel is increased by 200 percent by these artful additions.
This strategy is not unlike what one sees in informal communities, where an original rudimentary structure provides simple shelter for a rural immigrant family in the first decade, and in successive decades space is added above or behind the original box.
Urban designers should take note of the fact that in informal communities, less bound by policy, barnacled expansions occur naturally and without permits. In formal contexts policy approval is required, and policy means can be used to either inhibit (most often the case, sadly) or encourage this organic evolution.
“Hiving” and “barnacling” are two strategies for modifying existing buildings that have been instrumental in shaping traditional cities, such as this one in Hermoupolis, Greece. (Image courtesy of Island Press.)
Also the same almost everywhere in the developed world is the presence of millions of individual small parcels, in settings that we may call suburban but which in actuality cover most of our urbanized land. Hiving, then, is an infill strategy specifically aimed at adapting existing neighborhoods to accommodate an increasing urban population. Hiving is distinct from simpler concepts of infill development, which are not always grounded in financial reality—not always grounded in a firm understanding of the relationship between the price of land and the average incomes of local wage earners.
The typical Vancouver single-family home parcel, with or without a building on it, costs $2 million at this writing. Most of these parcels are between 3,000 and 3,500 square feet. Thus Vancouver land costs about $600 per square foot (actually much more if you subtract unusable setback areas). In the case of Vancouver, average families who earn $80,000 per year can afford (using the traditional calculus where 30% of family income goes to housing) to pay only about $400,000 for land and a home, or up to five times their annual family income (this assumes interest rates stay below 5 percent). They can thus (assuming a ballpark figure of 25% of total spent for the structure) afford about 500 square feet of land at $300,000. But most Vancouver parcels, now occupied by detached single-family type dwellings, are roughly 3,500 square feet. Wage earners in Vancouver cannot afford this much land. The solution for Vancouver, using very simple math, is to allow these parcels to be divided between at least five families. So each family gets a very modest amount of land, approximately 500 square feet. If the average unit size is 900 interior square feet (just enough space for a two-bedroom unit), the total built square feet of habitable space on the parcel will total 4,500 square feet.This is roughly 1.5 times the square footage of the bare land.
Adding new dwelling units to existing lots, Fleming Street, Vancouver. Two former single-family lots combined to create locations for at least nine dwelling units. If each structure included a secondary suite this could easily contain eighteen dwelling units. (Image courtesy of Island Press.)
In some ways the easiest way to redevelop [a] parcel would be to tear down the existing house and start over. This is probably suitable in the many cases where the existing structure is modest and in need of extensive repair. But the majority of Vancouver homes are of a higher quality and worthy of continued use. It is also more sustainable to reuse as much of any existing structure as possible, of course.
The proposal here is to reuse the principal structure, “barnacle-ing” on additions and dormers, often more than doubling total usable area. A second strategy for gaining space is to lift the main structure up and provide a new foundation underneath, perhaps moving the structure in the process to create a more practical site configuration. Happily, Vancouver parcels also have rear lanes. This dual access to public rights-of-way makes it easy to build, service, and occupy “lane house” dwelling units at the rear of the lot.
The astute reader may have noticed a sleight of hand. Urban designers typically suggest solving the affordability problem by building much larger buildings than the ones discussed above. If five units is affordable, why not sixty on the same piece of land? Build much higher and reduce the land component of the unit price! In Vancouver we have encountered a number of problems with this philosophy. First, whenever a piece of Vancouver land is rezoned to allow higher-density development, its speculative value inflates beyond reason. If the increase in allowable density is by a factor of ten, the increase in the speculative value of the parcel increases in lockstep. Parcels that sold only a few months before for $2 million are suddenly flipped for ten times that amount. Neither the home buyer nor the developer gains from this transformation. Any gain from the increased allowable density goes to the land speculator, whose gains are doubly outrageous because they accrue so passively.
Second, tower blocks are ill suited for most parts of the urban landscape, for reasons that Jane Jacobs made clear fifty years ago. Her insights have been incorporated into the arguments of neighborhood residents who successfully and rightly oppose tower block proposals in their neighborhoods. Finally, as has been discussed more than once in this volume, high-density tower blocks are not resilient, are expensive per square foot to build, and are not efficient users of energy and resources. For this and other reasons we have found that a strategy of hiving is a more reasonable way to dramatically increase the allowable density over vast areas of the urban landscape, without the “feeding frenzy” unleashed when land is released one parcel at a time for very high-density development, and without the intense neighborhood resistance to high-density projects requiring large land assembly. In Vancouver (and in other cities experiencing a similar failure of the housing market), a hiving strategy, if widely deployed, could triple the city’s housing supply in time, providing more than enough new homes for even the most ambitious population growth goals.
About the Author
Since 1994, Patrick M. Condon has organized and participated in over a score of design charrettes for sustainable communities. He is a senior researcher in the Design Center for Sustainable Communities at UBC, whose goal is to advance the practice of sustainable community development in North America. He holds a BSc and a MLA from the University of Massachusetts Amherst. His 20 years of experience in government and as a scholar include his former role as Director of Community Development for the city of Westfield, Mass. He came to UBC in 1992 to be the Director of the Landscape Architecture Program; in 1994, he became the UBC James Taylor Chair in Landscape and Liveable Environments. As the James Taylor Chair at UBC, Patrick leads the Headwaters Sustainable Development Demonstration Project, a Surrey, BC community being constructed using sustainable development principles. He is the author of numerous books, including Design Charrettes for Sustainable Communities (Island Press).
You can connect with him on Twitter at @pmcondon2.
Don't be scared off by the policy changes and wonky jargon: Incremental development is fundamentally about seeing potential in your neighborhood, about observing problems and then coming up with creative ways to address them.