Falls Church Planning Commission weighs wide-ranging changes to accessory dwelling rules

Falls Church City Planning Commission members spent the bulk of their Wednesday meeting on a work session about proposed changes to the zoning code to allow and regulate accessory dwelling units, or ADUs, across R1A, R1B and RM districts.

The proposal under discussion would add a code definition for ADUs that focuses on use as a habitation and on minimum fixtures ("including at least 1 bathroom and 1 kitchen"), introduce rules to permit detached ADUs, and set multiple dimensional options for detached units: a 5-foot setback with a 20-foot midline height or a 10-foot setback with a 25-foot midline height. Staff also proposed a 1,000-square-foot cap for detached ADUs, a maximum occupancy of three persons for those units, and an intent that special-use-permit reviews for ADUs go to the Board of Zoning Appeals (BZA/VZA) rather than the full Planning Commission.

Project planner Jack Trainor walked commissioners through the draft code and supporting analyses, describing the new definition, the occupancy recommendation and a "bulk plane" analysis that compares proposed ADU height/setback pairs with existing rules for principal structures. Trainor said staff found about 1,500 existing accessory structures in the city’s R1A and R1B districts; the average footprint was 248 square feet and the smallest 75% were under 326 square feet — sizes generally too small to be a dwelling without significant alteration.

"We've provided an amended definition to define an accessory dwelling ... including at least 1 bathroom and 1 kitchen," Trainor said. He told commissioners the 3-person occupancy cap "is based on ... conversations with the zoning administrator and building official" and is intended to preserve the ADU's subordinate status to the principal dwelling.

Public comments at the start of the meeting underscored the divide within the city. Jean Gresco, a North Fairfax Street resident, urged enforceability measures and asked the commission to "institute a prohibition on water and sewage utilities going into accessory structures. It's hard to secretly turn a structure into a dwelling if there isn't running water." Another resident, Jennifer Veal, said she opposed the draft, arguing it would "change the character of the city" and could strain schools and parking. By contrast, Robert Lajonesse of South Virginia Avenue said he was "very supportive of accessory dwelling units" and urged the commission to distinguish rules for new construction versus existing buildings, particularly on parking requirements.

Commissioners debated several technical trade-offs at length. Several members expressed concern that the draft’s taller, closer option (25-foot midline at a 10-foot setback) would create intrusive massing on small R1B lots. Commissioner Krasner said he thought the 25-foot option would allow a structure "that a lot of folks would find... obtrusive," noting such heights can raise privacy, shadowing and maintenance issues for neighbors. Commissioner Stevens — who said he had reviewed ADUs built in Arlington — said he was "okay with the 5-foot setback" given modern mechanical systems and tree‑preservation trade-offs but asked staff to confirm how many stories the height options would allow in practice.

Several commissioners and staff discussed alternatives: measuring to roof peak rather than midpoint; using different height/setback pairs for R1A versus R1B; a two-tier approach (a by-right envelope plus discretionary BZA review for larger or closer proposals); limits tied to lot size or to a percentage of the primary dwelling; and exemptions or allowances for interior/attached ADUs (basements or garage conversions). Trainor said staff is continuing to collect data from neighboring jurisdictions (Alexandria, Fairfax County and Arlington) and that Seattle's ADU experience was included as an example: Seattle allows up to 1,000 square feet and has published annual reports showing actual built sizes.

Staff also flagged ancillary issues that will affect implementation: separate addresses and separate utility meters can trigger larger utility infrastructure requirements and cost tens of thousands of dollars; existing nonconforming accessory structures could be converted to ADUs through a conditional or special-use permit but could not expand their footprint; tree-canopy and impervious-surface rules are checked at certificate of occupancy but grading triggers that require construction-level review remain sized-based and lot-dependent.

Trainor told commissioners of the schedule staff is working toward: the Planning Commission is expected to finalize a recommendation at a March 5 public hearing that will inform a city-council work session on March 10, and council final action is currently scheduled for March 24. "The planning commission is recommended to make its recommendation to city council by March 21, 2025," Trainor said.

Why it matters: ADU zoning changes would affect how homeowners can add rental units or family housing on single-family lots and could change development pressure, tree protection, on‑street parking and school enrollment patterns. Commissioners repeatedly noted trade-offs between enabling homeowners to add housing and preserving neighborhood scale and privacy.

Next steps: Staff will return to the commission with clarified language and more comparative data, owner‑occupancy and addressing/utility consequences, and refined options for setback/height choices. The commission scheduled another work session in February and a final public hearing on March 5 that could produce a formal recommendation to council.

Ending: Commissioners closed their ADU discussion after nearly three hours of technical and policy questions and signaled they expect more data from staff before a final recommendation in March.