A communication transmitted from Yi-An Huang, City Manager, relative to Policy Order Number 2025 #25 regarding a zoning petition on maximum unit size

Melissa Peters | Assistant City Manager for Community Development Sandra Clarke | Chief of Administration & Operations 344 Broadway Cambridge, MA 02139 [phone removed] cddat344@cambridgema.gov To: Yi-An Huang, City Manager From: Melissa Peters, Assistant City Manager for Community Development Megan Bayer, City Solicitor Date: June 12, 2025 Re: Response to Policy Order 2025 #25 Re: Zoning for Maximum Unit Sizes The above-referenced Policy Order asks staff to “… present a zoning petition to the City Council for consideration on maximum unit size.” This Policy Order is related to a concern that the recently adopted Multifamily Housing Amendments, which relax many dimensional limitations for residential uses, may result in larger-sized housing units instead of its intended effect of promoting a greater number of housing units. This response provides background information about the issue and suggests alternative approaches. There are legal constraints on the approaches that can be considered and there are pros and cons that should be weighed by Council before deciding how to move forward. It would also be helpful for the Council to consider where to prioritize this issue among other zoning initiatives under consideration. Background After the Multifamily Zoning Amendments, all types of housing – including single-family, two-family, townhouse, and multifamily – are permitted in all zoning districts. There are no FAR or lot area per dwelling unit limitations for residential development, and other dimensional requirements like setbacks are more relaxed than before. Because the prior zoning constrained the type of housing, the number of units, and the amount of floor area allowed in many neighborhoods, there was little new multifamily development in those areas. Redevelopment often resulted in little change to the number of housing units on a lot, in some cases resulting in fewer units than existed. Many projects involved modest expansions of existing homes through dormers or other additions, sometimes resulting in larger homes with anywhere from around 2,000 to 4,000 square feet of floor area. Many projects required some form of relief from the Board of Zoning Appeal (BZA). On balance, there has still been a net increase in the number of residential units in neighborhoods across the city, but a very small one. Property owners now have a much wider range of development options for their sites. They will likely take different approaches to development, depending on the unique characteristics of a particular site and the goals of the owner/developer.

City of Cambridge Community Development Department Response to Policy Order 2025 #43 Re: Zoning Priorities June 12, 2025 Page 2 of 8 Under the new zoning, some redevelopment projects that were typical under the prior zoning – like additions or enlargements to existing homes – are now less likely to need BZA relief. As long as there is demand for larger-sized units, either from new homebuyers or existing homeowners wishing to expand, there are likely to be some as-of-right proposals to create larger-sized units. However, the new zoning also enables development with more units and smaller units, which were not previously allowed. Because there is strong demand for more units of this type, this new alternative will likely be appealing to many owners and developers who are seeking to acquire sites. It will be hard to say exactly how many of what type of project will occur until the market has had time to respond to the recently adopted changes. From a policy perspective, Cambridge has long encouraged a diverse range of housing sizes and types, including larger housing units that are attractive to families with children. State housing policies have reinforced this goal (see below). However, there is a concern that housing units that are unreasonably large might be too expensive for families that might otherwise benefit. The threshold between “large enough for families” and “unreasonably large” is subjective and will depend on the specific needs of the family. Legal Considerations There are a few provisions in Massachusetts General Laws Chapter 40A (the “Zoning Act”) that constrain the ability to regulate unit size. • The “Dover Amendment” (Section 3) states that “No zoning ordinance or by-law shall regulate or restrict the interior area of a single family residential building …” but does permit reasonable regulation of lot characteristics like height, bulk, lot area, setbacks, open space, and parking. Recent opinions by the Supreme Judicial Court have sought to clarify what types of regulations are permissible. The SJC has interpreted that language and held that “regulation of single-family residences pursuant to the authority in the proviso of G.L. c.40A, s.3 second paragraph, including bulk regulation by floor-to-area ratio, is a proper exercise of the zoning power, provided the effect of such regulation on the interior area of such structures is incidental.” Additionally, “dimensional, bulk, and density requirements may properly regulate single-family residences so long as they do not set minimum or maximum levels of interior area.” 81 Spooner Road, LLC v. Town of Brookline, 452 Mass. 109 (2008). Therefore, zoning requirements cannot set a maximum for single- family unit size. There may be options, but there is also a risk to any regulation that may be viewed as an unreasonable attempt to limit the interior size of single-family homes. • The “MBTA Communities Act” (Section 3A) requires any community with MBTA service to zone some portion of the city for as-of-right multifamily housing “without age restrictions and … suitable for families with children.” Regulations promulgated by the Executive Office of Housing and Livable Communities have clarified that

City of Cambridge Community Development Department Response to Policy Order 2025 #43 Re: Zoning Priorities June 12, 2025 Page 3 of 8 limits on dwelling unit sizes are not permissible in zoning districts that are designated for Section 3A compliance. In Cambridge, Residence C-1 is not currently within the set of zoning districts identified for Section 3A compliance. • The “Uniformity Principle” (Section 4) states that “Any zoning ordinance or by-law which divides cities and towns into districts shall be uniform within the district for each class or kind of structures or uses permitted.” As discussed in other contexts, this limits the ability to create different rules that depend on the existing conditions of a lot, such as allowing existing single-family homes to remain while prohibiting the conversion of two-family homes to single-family within the same district. As an exception, there are provisions in Section 6 of Chapter 40A that allow for the maintenance of nonconforming conditions on a lot that existed before a change in zoning was enacted. Alternative Approaches Given the background and constraints, there are several ways to think about setting zoning standards that would discourage excessively large units. These approaches are summarized in a table on the last page. 1. Unit Size Limitations Only for Multiple-Unit Development Direct unit size limitations cannot be imposed on detached single-family homes, but they could potentially be applied to two-family, townhouse, or multifamily development. The caveat is that they could not be applied in zoning districts that are identified as contributing to Cambridge’s compliance with Section 3A. The outcome of this approach would be to prohibit projects resulting in a building with multiple units exceeding a particular unit size. This could be a limit on each unit or an “averaged” maximum unit size based on dividing the total Gross Floor Area by the number of units. Development with a small (but greater than one) number of larger units within a large building would be prohibited or would require relief. In addition to requiring attention to how such a change would impact Section 3A compliance, this approach could also create the perverse incentive of encouraging owners or developers to pursue detached single-family development if the unit size limitations for other forms of multiple-unit development are found to be too restrictive. 2. Stricter Dimensional Standards for Single-Family Homes Although the interior floor area of single-family homes cannot be directly limited, the “Uniformity” section of Chapter 40A makes it possible to set different dimensional regulations for different types of structures. It may be possible to create more restrictive dimensional standards for single-family homes (as well as two-family homes and/or

City of Cambridge Community Development Department Response to Policy Order 2025 #43 Re: Zoning Priorities June 12, 2025 Page 4 of 8 townhouses, if desired) such as reintroducing FAR limitations, lowering height limits, or imposing greater setback and open space requirements. This approach could help serve the goals of the Policy Order by disincentivizing the development of large single-family (and/or other non-multifamily) buildings and making multifamily development more advantageous. This approach would also reintroduce constraints on expansions and enlargements of single-family (and-or other non-multifamily) buildings, requiring more of those types of projects to seek relief primarily from the BZA as was common before the Multifamily Zoning Amendments. It would restrict developers attempting to create larger units to sell on the market, but also homeowners attempting to create more space for their own use. Overall, the impact would be greater on single-family homes that are more densely developed, which are more typical in northern and eastern Cambridge. Large single-family homes on larger lots, which are more typical in western Cambridge, are more likely to be conforming to FAR, height, and setback requirements, and therefore less impacted. Additionally, single- and two-family homes receive greater preexisting, nonconforming protections under the Zoning Act, G.L. c.40A, s.6, than other types of structures, so depending on the site-specific conditions and project proposal, existing single-family homes may be able to construct additions that result in a larger structure than allowed under the single-family dimensional regulations. Finally, although “bulk” requirements are generally allowed, there is the potential risk of challenge if the requirements are seen to unreasonably prevent a property owner from enlarging the area of a single-family dwelling. 3. Minimum Unit Density Standards The idea of a “maximum lot area per dwelling unit” standard has been suggested. This would be the inverse of the “minimum lot area per dwelling unit” standard in the prior zoning, which essentially limited the number of units that could be built on a lot of a given size. The inverse approach would be to essentially mandate a minimum number of units that are required on a lot of a given size. This would be an untested approach in Cambridge, and little is known about how this is effectively used elsewhere. In principle, the effect of this approach would be to prevent building a single-family home on a larger lot, but to allow a similarly-sized development with more units. It could also prevent a building permit for a project that reduces the number of units on a lot if that number is below the minimum threshold applicable to that lot. Many existing lots will become non-conforming if they do not have enough units to meet the threshold – likely in areas of the city that have less housing unit density overall. Enlargements of existing units might still be permissible if they do not increase the

City of Cambridge Community Development Department Response to Policy Order 2025 #43 Re: Zoning Priorities June 12, 2025 Page 5 of 8 nonconforming conditions on the lot, so larger unit sizes might still result. However, some types of changes might require additional relief. There are many potential issues with this approach. In addition to discouraging the construction of new large buildings with fewer units, it would prevent property owners who choose to build or maintain smaller buildings on larger lots, even if the units are reasonably sized. As noted above, it would make many lots non-conforming again (after the Multifamily Zoning Amendments brought much of the city into greater conformance) but would not necessarily prevent the enlargement of existing single-family homes. There is also a great deal of uncertainty around how a standard that requires a “minimum intensity” of development would work in practice, given that there are many different types of existing conditions and proposed changes that need to be reviewed for zoning compliance. Property owners might be forced to seek relief for developments or alterations that are viewed as having very modest impacts. Enforcement could be a major challenge in cases where the existing conditions are unclear, where there are circumstances that might make it infeasible to maintain a minimum number of units, or where an owner claims to be creating the required number of dwelling units but in practice is not using the property to house multiple residential households. 4. Balanced Incentive Approach A final option would be to construct a “hybrid” type of approach that seeks to use some of the strategies above in a measured way to discourage the application of the Multifamily Zoning Amendments contrary to its intent. An example of such an approach could look like this: • Detached single-family residences (and potentially two-family and/or townhouse residences) could be limited to 3 stories above grade and 35 feet, as in the prior zoning. They would otherwise not be limited by FAR and would be subject to the same limitations on setbacks and open space that apply to all types of housing in the district. • Potentially, development above 3 stories and 35 feet could be subject to a maximum limitation on gross floor area per unit, or maximum lot area per dwelling unit. The advantage of this approach is that it helps redirect the height advantage created by the Multifamily Zoning Amendments away from single-family homes or buildings with larger units and toward the desired outcome of multifamily buildings with more units. However, it does so in a way that is not overly restrictive (assuming that three stories is a reasonable height for single-family and potentially two-family or townhouse development) and creates fewer nonconforming conditions in neighborhoods. There are still potential drawbacks to this approach, as with the approaches above. Attention would need to be paid to whether an explicit or effective limit on unit size would

City of Cambridge Community Development Department Response to Policy Order 2025 #43 Re: Zoning Priorities June 12, 2025 Page 6 of 8 create a Section 3A compliance issue. It also does not guarantee that larger-sized single- family (or two-family or townhouse) development would not happen, it simply adjusts the incentives to discourage those outcomes. 5. See How Trends Evolve Before Making a Change As discussed earlier, it will take some time for housing development markets to adjust to the recent major zoning reform. We will not know to what degree the market will favor the creation of larger units, as was the case under the previous zoning, and to what degree it will shift toward producing more units with smaller average sizes. The Multifamily Zoning Amendments included a provision for annual review of housing trends by the Planning Board and City Council. This process will provide a better opportunity to assess how development is responding to the recent changes and to respond in a more targeted and meaningful way. In the short-term, there may be instances of undesired development outcomes. In the months following the adoption of the Multifamily Zoning Amendments, some projects that started under the prior zoning, which typically had fewer units and often required BZA relief, have revised their plans to take advantage of less restrictive requirements while maintaining the concept of the original project. Those cases might be viewed positively or negatively, but are not indicative of long-term trends. Though it is too early to predict outcomes, conversations since the adoption of the Multifamily Zoning Amendments show that there is considerable interest in new multifamily development. Adding a new requirement to the zoning so soon after a major comprehensive reform might introduce new considerations for property owners and a range of unforeseen consequences that could undermine the larger goals of the reform effort, which sought to enable more housing by simplifying zoning regulations and removing regulatory impediments. Questions To further this conversation, input is needed from the Council on the following questions: • Which option(s) are preferred? What is the desired balance of achieving the objective of limiting housing unit sizes versus the potential adverse consequences? • If there is a desire to set a standard based on preventing unit sizes that are unreasonably large, how should that size threshold be determined? Dwelling units in Cambridge vary greatly in size, and different households will have different size needs based on a range of characteristics.

City of Cambridge Community Development Department Response to Policy Order 2025 #43 Re: Zoning Priorities June 12, 2025 Page 7 of 8 • If the Council wants to move forward on one of the above options, how should that be prioritized among the other zoning initiatives, which currently include the following: o Comprehensive rezoning of Cambridge Street and Massachusetts Avenue o Comprehensive rezoning of Central Square o Requirements to promote solar access o Allowing retail uses in residential districts

City of Cambridge Community Development Department Response to Policy Order 2025 #43 Re: Zoning Priorities June 12, 2025 Page 8 of 8 Summary Table of Zoning Approaches Approach Rationale Pros/Cons 1. Unit size limits for multi-unit dwellings (two-family, townhouse, multifamily) Zoning cannot directly limit floor area of a single-family dwelling but other housing types can be limited • Avoids overly large units in multi-unit development • Could incentivize single-family over multifamily development in some cases • Can only be applied in non-MBTA Communities designated districts 2. Stricter limitations on single-family dwellings (and/or two-family or townhouse) Different FAR, Height, Setback and other “bulk” standards can be applied to different types of dwellings • Incentivizes multifamily development over single-family (and if desired, two-family or townhouse) • Could reintroduce impediments for homeowners looking to expand, likely resulting in more BZA requests 3. Minimum unit density / maximum lot area per dwelling unit Require a minimum number of units per area of a given lot as a base dimensional standard • Can be applied as a “bulk” requirement across all types of dwellings • Could unreasonably constrain a property owner’s choice to build a smaller building than what’s allowed • Untested approach that could have many unintended consequences and enforcement issues 4. Balanced incentive approach Combine height limit for single-family (possibly two- family and/or townhouse) with a unit size or minimum density standard for taller multifamily development • Incentivizes multifamily over single-family • Still enables single-family enlargements, modifications, and new development as-of-right at a lower height • Maximum unit size / minimum unit density standards still could impact MBTA Communities Act compliance (per #1) or choice to build smaller buildings (per #3) 5. See how trends evolve before making a change Still not much is known about how long-term development trends will be impacted by recent zoning reform • More time and study (including annual review process) will provide more information about the direction of housing development trends • Changes at this early stage could unintentionally impact larger goals of multifamily zoning reform • Could be some unfavorable development outcomes in the short-term