Real Talk About ADUs
In case you missed my Interview this morning on 980 WCAP Lowell with Gerry Nutter, we spoke a little bit about a controversial subject in the Lowell Community: Accessory Dwelling Units (aka ADUs). Consider this the Extended Cut...
TL;DR: There is a right way, and a wrong way to regulate housing production with ADUs. The language approved by the MA State House last week is flawed, particularly with "As-of-Right" measures that bypass Local Zoning review, and the elimination of an Owner-Occupancy requirement. There are concerns with Building Code compliance / enforcement that have seemingly been ignored in the debate, and hard truths that need to be confronted whether ADUs move the needle in creating affordable housing.
As an Architect, I know a lot about these. Each year, more prospective clients around the Commonwealth ask me to design an ADU, and our approach adjusts based on the Local Zoning By-Laws in effect. In MA, all 351 Authorities Having Jurisdiction (AHJ) follow 780 CMR: The State Building Code (that's important, and a point I'll circle back to). A few years ago I served on the International Code Council's Building Code Action Committee, and had the opportunity to pen the Model Code language that would ultimately be adopted in the 2024 Edition of the International Zoning Code (IZC). Our research was based on policies across 38-states at the time, and was considered favorably during the consensus-driven Codes Development Process with little resistance. For this walkthrough, I'll provide context for the current debate, followed by an explanation of my Model Language, and how that measures up with pending legislation.
Background: Last week the MA House voted 145-13 to approve Governor Healey's Housing Bond Bill (H.4707) which included provisions allowing for ADUs "As-of-Right" in One-Family Zoning Districts statewide. It is with regard to these provisions, and the apparent lack of consideration that the State House gave to the recommended Model Zoning Code language wherein I have objections, and am hoping the MA Senate will push for further Amendment.
ADU Provisions are provided in Section 903 of the IZC (if you want to read along): <https://codes.iccsafe.org/.../chapter-9-special-regulations>
What is an ADU? With the ICC, we defined it as "an additional, subordinate dwelling unit on the same lot that is entirely within a dwelling unit, attached to a dwelling unit or in a detached structure." The State House language is broader, opting not to articulate on the possible locations for an ADU; that may warrant clarification from Local Jurisdictions on the back end.
Where Should ADUs be Permitted? Though my colleagues and I at the ICC found examples of ADUs in various Zoning Districts around the country (the most challenging being those appurtenant to Townhouses), we agreed that in practice, the location should be restricted to Single-Family Zoning Districts (Section 501.1). That does not mean that every 1-Family Dwelling in a Single-Family Zoning District is a good candidate for building an ADU.
Should an ADU be Permitted "As-Of-Right?" Per Section 903.1.1 and 903.1.2, we said NO. A Conditional Use Permit subject to renewal every few years provided a responsible means for a Municipality to ensure that Design Standards were followed per the Zoning By-Laws, Building and Fire Safety Codes were in compliance, and that Occupancy Permits were in place especially if there is an applicable Rental / Leasing Agreement requiring consideration by the local Tax Assessor. The MA State House Language seeks to streamline the permitting process by effectively removing Local Zoning Boards from the equation, and passing the authority to approve onto the Building Department.
How Many ADUs can be Built on a Lot? One (1); Additional ADUs would be subject to Special Permit consideration. The MA State House language is compatible with IZC Section 903.2(1).
Should there be an Owner Occupancy Requirement? Per Section 903.2(2), we said YES in the strongest of terms (and there was debate). It could be in the primary Dwelling Unit or in the ADU, but that "familial" connection is important for numerous reasons. Though many Municipalities limit homes to one (1) Kitchen as a means to ensure that illegal rental apartments are not being created, the Residential Building Code doesn't actually prohibit it. Where there is a close personal connection, i.e. a heightened sense of trust, a common phrase Building Officials use is "free-flowing" continuity between units. This actually aligns with the historical analogues of ADUs: on-site servants' quarters, caretaker's lodging, and carriage houses; these people were considered as extensions of the family unit. The MA State House language disagrees; they will NOT require Owner-Occupancy of either unit; I call this the California Model. This is where the Building Code (780 CMR) returns to the conversation, and we encounter logistical issues.
Why? For as successful as we were in getting ADUs integrated into the International Zoning Code, our efforts to get compatible language into the International Residential Code (the Model Code we amend in MA) were met with fierce resistance, and ultimately withheld during that Code Cycle. The reality is that the Residential Code firmly understands how to regulate the design of Dwelling Units, but is fully blind to the concept of an ADU (there's no Definition in Chapter 2). Where the aforementioned familial connection is considered, there is a reasonable allowance for a Building Official to treat the ADU as an extension of the Dwelling Unit. No harm, no foul (as long as the Owner doesn't rent it out illegally). That's not the case anymore when one unit is effectively a Rental Apartment. The Prescriptive Path to designing for this scenario is to treat the building as a 2-Family Dwelling. That's fine, but also entails further requirements / upgrades for compliance including but not limited to providing fire-resistance ratings between the two (2) Dwelling Units. My expectation is that the cost to build ADUs will actually increase as a result of the MA State House language, as Building Officials find themselves compelled to hold ADUs to a higher safety standard than would otherwise be permissible by maintaining the Owner-Occupancy mandate.
Not language specific, but there is a secondary conversation here about how this affects the Housing shortage. I've been comfortable with the Owner-Occupancy language because that aligns with goals for keeping college-aged children living at home longer, and to allow elderly relatives to age-in-place with dignity in the Communities they love. I'd consider those options supporting multigenerational housing a good thing, and compatible with Affordable Housing. By eliminating the Owner-Occupancy component, ADUs are now pursuing a Market Rate agenda. If anyone has the right to pursue construction of an ADU Rental Apartment at their 1-Family Dwelling (with a Building Permit), if it is for anyone other than a close friend of family member, they are going to rent it in accordance with whatever the Market allows. I'd be interested to hear from the Candidates running for Register of Deeds in the Middlesex North District what they think about ADUs under the current system versus what is on the horizon.
What is the Right Size for an ADU? We based Section 903.2(4) broadly based on conditions around the U.S. with full recognition that Local Municipalities would amend as needed. As I recall our minimum square footage was based on prevailing language for Tiny Homes, and the largest was based on observations in Texas (you had to know ADUs would be bigger there). The MA State House language allows ADUs to be either less than 50% of the square footage of the primary Dwelling Unit, or 900 square feet, whichever is smaller. The 50% threshold matches the IZC, and the 900 square feet makes sense since our current Energy Code in MA takes on a bigger presence with Additions larger than 1,000 square feet.
Does an ADU Require a Separate Entrance? Yes, we are on the same page here. Oddly enough, this can be an issue with current ADU language in various Zoning By-Laws around the State. I find it concerning that some Municipalities seemingly discourage additional means of egress from being provided. In the interest of maintaining the character of One-Family Zoning Districts, I would support Local efforts to restrict additional exterior doors to the Sides and Rear versus multiple Front doors.
How Many Bedrooms Can an ADU Have? The MA State House is silent on this; we said no more than two (2) in Section 903.2(6). From what I recall, there we legal concerns whether a restriction could be set at one (1).
Is Off-Street Parking Required? In Table 801.2.1 of the IZC, we said that it was reasonable to require one (1) off-street parking space for an ADU; if a Municipality disagreed, they would be free to amend this in their local Zoning By-Law adoption. The MA State House language is a more nuanced. If a Property is located within 0.5 miles of Public Transportation, then no additional parking need be provided. Further than 0.5 miles, a Municipality cannot require more than one (1) additional off-street parking space. Lastly, the creation of an ADU cannot remove off-street parking from a Property making it non-compliant. Recognizing that we live in a car culture, and without knowledge of who is living in the ADU (possibly someone that has mobility issues), and that the availability of off-street parking / traffic congestion varies from Town-to-Town, my preference would be to leave parking requirements to the Local Jurisdiction.
What About Utilites? In Section 903.2(9) we kept it simple, "adequate provisions for electricity, water supply and sewage disposal." The MA State House language is broader, with only a passing reference to "sanitary facilities." This could lead to another challenge for the Municipalities who find themselves pressed into compliance with the new ADU requirements. The capacity of utilities varies widely, and I foresee properties with on-site wastewater (septic) systems in particular, finding it difficult to get approvals without costly upgrades.
It's understandable that the State wants to encourage Housing production of all varieties, but this is a good example where more could have been done with less. Regulated responsibly, ADUs do not need to mean the end of Single-Family Zoning Districts, and Local Jurisdictions have a right to be present in the Planning decisions that affect their Community. My preference would have been for the Housing Bond Bill to create the obligation so that "no municipality shall unreasonably restrict the creation or rental of an accessory dwelling unit" on their own terms. At their discretion, a reference to the Model Zoning Language in the International Zoning Code could also be provided.
Note: The attached image is a Diagram prepared by the American Planning Association.
