Hidden density in single-family neighborhoods: backyard cottages as an equitable smart growth strategy

Secondary units, or separate small dwellings embedded within single-family residential properties, constitute a frequently overlooked strategy for urban infill in high-cost metropolitan areas in the United States. This study, which is situated within California’s San Francisco Bay Area, draws upon data collected from a homeowners’ survey and a Rental Market Analysis to provide evidence that a scaled-up strategy emphasizing one type of secondary unit – the backyard cottage – could yield substantial infill growth with minimal public subsidy. In addition, it is found that this strategy compares favorably in terms of affordability with infill of the sort traditionally favored in the ‘smart growth’ literature, i.e. the construction of dense multifamily housing developments.