Backyard cottages don’t “scream Manhattanization or even…smart growth,” but build enough of them and they could achieve the same effect.
Planning scholar Jake Wegmann says that if California relaxed its zoning regulations, the East Bay–Oakland, Berkeley and El Cerrito–could accommodate 8,700 cottages by 2040. That’s more housing than could be built using a traditional strategy of infilling multifamily buildings near transit hubs, which would produce 7,900 units of housing and take between 18-43 years. Across the bridge in San Francisco, legalizing backyard cottages could increase the available housing supply by 33 percent.
Wegmann’s recent paper in the Journal of Urbanism with colleague Karen Chapple says that the units compare favorably, cost-wise, to building dense multifamily buildings.
This could be simply due to the fact that cottages are just… smaller. Than your typical single-family house, at least. And landlords renting out the backyard cottage to their aging parents or boomeranged college grad might not charge market rent. 82 percent of the clients of one cottage consultant have a tenant in mind: either their adult kids, or themselves when they retire, or both.
Cottages, even if they have cute little gingerbread trim, are a type of ADU. ADUs are not popular in some circles because of NIMBYist fears of property values dropping, neighborhoods changing, or parking problems. And according to some, backyard cottages are more expensive than building an attached wing to an existing house, which would be a good way to add density if you didn’t mind giving up some privacy. They’re also illegal in many places (thanks to those exact concerns).
But Wegmann is hopeful that cottages can at least augment other infill strategies. As he told Fast Co/Design: “My prediction is that we will continue to have structures that we today call ‘single-family houses’ for centuries to come, but that increasing numbers of them won’t be occupied by single families, and eventually the law will evolve to reflect changing attitudes,” he says. “Some of them will sprout cottages in their backyards. Of course, these changes won’t happen overnight.”