Falls Church council narrows ADU rules; council splits on rear-yard coverage and setbacks

Falls Church City Council spent most of its March 10 meeting on a final work session over proposed zoning changes to permit accessory dwelling units (ADUs) in single-family neighborhoods.

Staff and Planning Commission recommendations remain the starting point: ADUs would be allowed by right in R‑1A and R‑1B districts, conditional (one‑time special use permit) in RM, and subject to residential building-permit review. The Planning Commission recommended limiting ADUs to 50% of a primary dwelling’s gross floor area (GFA) or 1,000 square feet, whichever is less; councilors asked staff to examine an allowance for smaller primary homes so owners of small houses could build larger ADUs without being unduly constrained. Council broadly favored keeping the 50% rule but asked staff to propose a safe harbor for homes under 1,000 sq ft (staff suggested a 60% ratio or a 600‑sq‑ft minimum as options to evaluate).

Council discussed several contentious points the Planning Commission raised:

- Height and setbacks: The commission proposed a sliding scale tying allowed height to the setback from the property line (e.g., smaller setbacks allow less height, larger setbacks allow taller ADUs). Supporters said the scale preserves proportionality between height and proximity; skeptics called the approach confusing and urged clearer thresholds. Several councilors said a 5‑foot minimum setback felt too small and asked staff to test intermediate numbers (8 feet) or confirm the charted ratios with clearer examples.

- Rear-yard coverage: Current code caps accessory-structure coverage of required rear‑setback areas at 30%. The Planning Commission recommended exempting ADUs from that 30% cap to give property owners flexibility when existing sheds, trees, or lot geometry make siting difficult. Opponents warned that removing the 30% constraint could allow ADUs to dominate backyards and harm neighbors’ sunlight and privacy. Council did not reach consensus; staff will return with options, including an intermediate cap (40–50%) or a special‑use/variance pathway for exceptions.

- Owner-occupancy and rental rules: The Planning Commission recommended no owner‑occupancy requirement; councilors debated that issue at length. Several members said an owner‑occupancy mandate would better preserve neighborhood character and the ordinance’s original intent to support family housing or aging‑in‑place. Others said owner‑occupancy rules risk legal challenges, reduce housing diversity, and are hard to enforce. The council kept staff’s recommendation (no owner‑occupancy requirement) for now but asked staff to include monitoring and enforcement options should commercialization concerns arise.

- Occupancy limits and unit count: The Planning Commission recommended limiting ADU occupancy to three people. Councilors voted to set the ADU occupancy cap at four people per accessory unit and to preserve a cap on total occupants per lot consistent with existing zoning (council asked staff to ensure the combined occupancy rules are explicit in the code).

- Existing accessory structures and HARB: The Planning Commission and staff recommended that conversion of pre‑existing accessory buildings built before 01/01/2024 remain subject to Board of Zoning Appeals (BZA) review (the commission asked that planning commission review remain in the loop). Historic‑district properties (HARB) will continue to be reviewed under the historic‑preservation rules; councilors asked staff to confirm references so HARB authority is not unintentionally reduced.

- Stormwater and disturbance thresholds: Councilors pressed staff on the environmental consequences of new ADUs, noting that a 1,000‑sq‑ft footprint often implies additional disturbance for staging and utility trenches; staff said projects that disturb 2,500 sq ft or more will require grading and stormwater plans and that most ADUs will not reach that threshold. Council asked staff for clearer guidance on basements, finished space, and how utility connections are counted for stormwater and permit review.

What’s next: Staff will return with clarified code language on the three outstanding policy questions (rear‑yard coverage, minimum setbacks and corner‑lot rules) and with sample code text so the council can review the exact ordinance language before the April 14 final consideration. Council requested the staff memo to note where councilors were split and to circulate it in advance of the next meeting so the public and council can review changes ahead of final action.

Selected direct quotes from the record capture the range of views: "This process has felt somewhat anti‑democratic" (Jennifer Veal, public comment about ADU outreach) and staff framing that the intent is to "make these units accessory and not become the main dwelling" (Council Member Gutt).

The council also asked staff to provide a mock permit checklist and to confirm how sewer/utility fees will be assessed (staff noted utility charges will be reviewed and that additional plumbing fixtures would be charged through a DFU/fee update). The council did not adopt final code changes at this meeting; it continued debate and directed staff to return with precise, draft ordinance language and feasibility analyses before the April final vote.

Ending: Council scheduled follow‑up material from staff and signaled willingness to consider modest adjustments (a small‑house exception to the 50% rule and clearer setback math) but left several questions open for the April consideration.