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From the Field

Regulating Basement Conversions in New York City

Experiments with Flexible Housing Legality

Ooha Uppalapati examines the regulation of basement apartments in New York City and the implications of proposed laws for both homeowners and tenants.

On August 30, 2022, the Comptroller of New York City, Brad Lander, released a report titled Bringing Basement Apartments into the Light. The report, which lists recommendations for the provision of “basic rights, responsibilities, and protections of basement apartment residents and owners” (NYC Comptroller 2022) marked the one-year anniversary of Hurricane Ida and the accompanying loss of life that was concentrated in basement and cellar apartments [1] in Queens and Brooklyn. The report proposes a Basement Resident Protection Law, which would establish “rights and responsibilities for basement dwellers and owners” irrespective of the unit’s legal status. For tenants, the law would extend protections from eviction and access to basic services and safety installations. [2] For homeowners, it would extend the right to collect rent, and the responsibility to register the occupied basement unit with a Basement Board and install safety measures. In other words, to enable an immediate provision of a set of safety measures, the rights to lease and occupy basement units are extended even without compliance with the entire set of housing regulations. In this piece I ask: how did the regulation of the practice of converting and occupying basements as dwelling units in New York City (hereafter referred to as “basement conversions”), and its enforcement, develop into these proposals? What are the previous interventions and what is their status? What are the opportunities and gaps in these interventions? I find that the current approach is an outcome of experiments with flexibility in the regulation and enforcement of legality to accommodate a greater number of basement conversions within adjusted standards for safety. I suggest that the applications of such flexibility, potentially an enduring feature in crisis management, should be assessed not only for their compliance with standards but also for their versatility and reach.

This article will first discuss basement conversions and their regulation. It will then identify and analyze three historical phases of special interventions. Finally, it will use this analysis to comment on the recommendations following Hurricane Ida and their implications for responses to the housing and climate crises. The article is a case study from New York City, that analyzes interventions into exceptional housing practices in a city where housing is largely regulated.

Regulating basement conversions

There are two key considerations regarding the legality and safety of basement conversions. The first consideration is that not all basement conversions are illegal in New York City. They are legal as long as their occupation complies with the City’s Building Code [3] and Zoning Resolution. Together, the Building Code and Zoning Resolution regulate for the safety of individual basement units and the increase in density due to the added unit. Safety is largely the responsibility of the Building Code, which mandates minimum floor area per occupant, ceiling height, egress, basic services, and safety installations. Density is largely the responsibility of the Zoning Resolution, which specifies floor area ratio (FAR), maximum dwelling units and minimum lot sizes. This leads me to the second consideration: the violations that render basement conversions illegal are not necessarily related to safety. Basement conversions that violate density limitations but comply with unit-level safety requirements are considered safe dwellings per the Building Code. As for basement conversions that do violate unit level requirements, they would fall under two categories in terms of safety. One of them would include conversions that are in violation of requirements related to the structural elements of the units, such as floor area, ceiling height, egress, etc. The other would include those conversions that are in violation of infrastructural requirements like access to basic services [4] and safety installations. [5] While both of these violations could render the unit unsafe according to regulations, the latter set of violations can be addressed through superficial installations rather than structural adjustments. These categories demonstrate that not all illegal basement conversions are unsafe and that, among those conversions that are unsafe as per regulations, a section of them can be brought up to safety standards by installing the required infrastructure.

Official responses to illegal basement conversions experiment with regulations and enforcement based on these categories. They include measures that target unsafe units for vacation, extend financial and technical assistance, incentivize safety installations, relax zoning regulations, adjust the building code, and those that separate immediate and longer-term safety responses. I observe that such measures in New York City, in addition to the general practice of regulation and enforcement, can be categorized into three historical phases: (1) elimination of illegal practice; (2) reinvention of practice for safety and affordability; and (3) the current phase of crisis management. I also observe that each phase resulted in higher flexibility in the regulation and enforcement of legality, with the most flexible propositions in the latest phase following Hurricane Ida.

Phases of official response

Phase I: elimination of illegal practice

Interventions in the first phase aimed to eliminate illegal basement conversions, problematizing them primarily as a threat to safety. Examples from this phase include Queens borough president Helen Marshall’s Illegal Conversions Task Force, which took effect multiple times in the late 1990s and early 2000s, and city mayor Michael Bloomberg’s initiative in 2011 to rapidly identify and intervene with regard to illegal units that would be prone to fire accidents. These measures did not succeed in eliminating illegal conversions, nor did they substantially reduce their presence. The City received around 83,000 illegal conversion complaints between 2000 and 2009, and around 76,000 complaints in the following decade (Chhaya CDC 2021). The continued prevalence of basement conversions led to the second phase of official response.

Phase II: reinvention of practice for safety and affordability

In the second phase, basement conversions are problematized as an unsafe, but affordable—and hence prevalent—housing practice. Interventions in this phase aimed to increase the volume of legal basement units, in addition to vacation of illegal ones. The second phase is constituted by the Basement Apartment Conversion Pilot Program (BACPP), launched in 2019. It takes the form of loans for renovating illegal basement apartments, to either bring them up to code or to facilitate new basement conversions if the structure qualifies. Both processes will be based on an altered Building Code legislation, Local Law Introduction No. 1004-2018-A, that additionally allows the conversion of cellars as long as they meet ceiling-height and egress requirements. [6] The BACPP loans are sanctioned for a 15‑year term. For the period of the loan, the owner signs an agreement that requires the current tenant to be allowed to return to the renovated unit under the earlier terms and for new units to be leased at no more than 80% of area median income (NYC Department of Housing Preservation and Development 2022b; Pratt Center for Community Development [n.d.]).

The scope of the BACPP’s expansion of legality does not include the Zoning Resolution, thereby excluding basement conversions that are safe at the unit level but rendered illegal owing to their location in neighborhoods zoned for lower density. In response, the Basement Apartments Safe for Everyone (BASE) campaign released a Blueprint for Basement Apartments (hereafter “Blueprint”) in 2021. The Blueprint recommends the omission of converted cellars from FAR calculations and the relaxation of parking requirements for the additional dwelling (BASE Campaign 2021).

The spatial distribution of legal basement and cellar conversions under the Blueprint model of the BACPP can be observed in the Basements Data Dashboard generated by the Pratt Center for Community Development. On the one hand, the distribution aligns closely with that of the current practice of illegal basement conversions, which I mapped using 311 illegal-conversion complaints as a proxy (see Figures 1 and 2). On the other hand, both distributions are concentrated in neighborhoods proximate to the floodplain.

The spatial distributions of the current and potential practice demand storm and flood water management infrastructure beyond current needs. Flexible definitions of legal housing to extend tenant and homeowner rights, in response to the housing crisis, are brought into examination under the lens of zoning and infrastructural demands, in response to the climate crisis. Safety is centrally implicated in both—as a concern in the growing, yet unprotected, practice of basement conversions, and as a concern for the infrastructural demands produced by a potential stock of legal basement conversions. The third phase of crisis management innovates at this juncture.

Figure 1. All 311 illegal-conversion complaints, community districts in New York City, 2020

Prepared for Chhaya Community Development Corporation, 2021.

Figure 2. Confirmed violations in the 311 illegal-conversion complaints, community districts in New York City, 2020

Prepared for Chhaya Community Development Corporation, 2021.

Phase III: crisis management

As discussed in the introduction, propositions in the third phase, most recently articulated in the Comptroller’s report and supporting statements, respond to these concerns for safety by delinking rights to lease and occupy from compliance with the full set of housing regulations. In terms of safety, this split first demonstrates an acknowledgment of the prevalence of basement conversions and the immediate need for safety within these units. Second, it identifies a need to address these concerns on a fast track. For the BACPP and the Comptroller’s recommendations, an infrastructural plan to service the identified and potential basement stock is yet to be developed. Such a plan will depend on the demand for new conversions, which remains to be assessed.


The recommendations in the Comptroller’s report warrant serious consideration. They go beyond measures for official recognition of basement and cellar units. They recommend a right to lease all of these units, irrespective of whether they violate the norms of safety or density, with a stipulation that homeowners reinforce the unit with prescribed safety installations. [7] The recommendations’ application to the entire universe of basement and cellar apartments certainly raises pertinent concerns regarding the limits of safety regulations, given that these regulations are parallel to, but not interlinked to, legal use. Nevertheless, a serious consideration of this approach to housing safety in illegal units, by granting rather than enforcing legality, is essential. The flexible approach to conferring legality can mobilize actions, both in the sphere of state action towards crisis management and in the mechanisms of the housing market. It is both a state-directed program of official recognition and an incentive for partially legal market mechanisms to meet a standard of housing safety. Having answered my initial question about how basement conversion regulations evolved into this juncture, I will end with this question: how will they develop from here? From the analysis in this paper, I will offer a possibility for consideration—that the theme of flexibility will find an enduring place in the growing problematization and management of the housing and climate crises. As evidenced in this case of basement conversions, it will operate in a field of incomplete but immediate measures. Critical concerns like safety will both be its primary objects for intervention and for redefinition. Its applications will be diffuse, rather than centralized, and fragmented, rather than complete.


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To cite this article:

Ooha Uppalapati, “Regulating Basement Conversions in New York City. Experiments with Flexible Housing Legality”, Metropolitics, 5 September 2023. URL :

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