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…