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Problem, research strategy, and findings: Planning scholars and practitioners once assumed informal housing was largely absent in the developed world; today they increasingly acknowledge its role in the United States. Recent evidence suggests that informal housing, or non-permitted construction, is a significant phenomenon inside incorporated cities, despite widespread regulations and code enforcement. Informal housing is a de facto source of otherwise scarce affordable housing in many locations, but also compromises health and safety and strains municipal infrastructure and fiscal health. Planners lack a means of measuring informal construction at the scale of individual cities. We propose such a method, and apply it to incorporated cities in California. Data limitations prevent us from precisely estimating the magnitude of non-permitted construction, but our findings suggest that informal channels are an important source of housing production, especially in the places where permitted construction is constrained.
Takeaway for practice: We urge planners to engage with informal housing issues, given the considerable importance of this hidden yet vital portion of the housing market as a means of providing living spaces amid tight housing market conditions. Our method for calculating the rate of informal housing addition is a useful tool for planners to gather basic facts about the informal housing market in their communities, a prerequisite for policy interventions.
Acknowledgments
We are grateful to the three anonymous reviewers for their insightful and challenging comments. Though he may not remember it, a brief but in-depth conversation with José A. Gomez-Ibañez in early 2014 about an early version of the methodology presented in this article was inspirational to us in getting it into published form.
Notes
1. As late as 2008, a book-length compendium of scholarship on rental housing policy in the United States with contributions from a “who’s who” of the nation’s leading housing scholars included not so much as a single mention of colonias or any other form of informal housing (Retsinas & Belsky, 2008).
2. In Texas, incorporated cities have the ability to regulate the subdivision of land within a buffer zone lying outside the existing city limits referred to as their “extraterritorial jurisdiction” (ETJ). As a consequence, colonias were developed beyond their nearby cities’ ETJs.
3. “Secondary units,” also referred to by various names such as “accessory dwelling units,” “granny flats,” “casitas,” and others, are small dwellings co-located with single-family houses on the same parcels. They take various physical forms, including separate detached backyard structures, dwellings located above garages, and others (Pfeiffer, 2015).
4. Our method cannot deal with unincorporated areas, since figures for all of the separate unincorporated communities within each county are grouped together in the CDOF data on which we rely.
5. For a detailed description of the various configurations of informal housing that exist in Southern California, see Wegmann (2015).
6. In the Western region during the 1990s, the average time from authorization to start was 0.8 months for single-family homes and 1.7 months for multifamily housing. During the first decade of the 2000s, the average time from start to completion was 6.7 months for single-family homes and 11.0 months for multifamily housing. Both sets of figures are according to the U.S. Census Bureau Survey of Construction (U.S. Census Bureau, Residential Construction Branch, 1990–2010).
7. CDOF reports completion and demolition data are only available from 1998 onward, and fewer than half of jurisdictions reported them. Such incomplete data are suitable for validation purposes only.
8. Neuwirth (2008) uses a variant of this method to estimate the levels of informal housing addition at the neighborhood level in New York City. His method, however, does not address loss rates.
9. Every state provides for the keeping of records on jurisdiction-level population estimates, updated yearly, similar to that of the CDOF. Such estimates are needed to annually allocate state spending to localities on the basis of their population.
10. A study that replicates this one at the national scale would be needed to know exactly where these concentrations are located, but obviously does not yet exist.