Planning board previews town‑meeting change to MBT3A inclusionary‑housing rounding and threshold

The Winchester Planning Board on Oct. 21 previewed a proposed bylaw change that would adjust inclusionary‑housing math in the MBT3A overlay district, bringing its unit‑count thresholds and rounding rules into parity with other downtown zoning districts.

Chair of the board gave the presentation and said the amendment will lower the threshold at which inclusionary requirements apply (from 10 units to six) and change fractional‑unit treatment so that decimals of 0.5 or greater round up to the next whole required unit. The change is framed as a narrow technical fix intended to prevent an identical development from producing fewer required affordable units when it elects MBT3A overlay zoning instead of the underlying downtown zoning.

Why it matters: under current MBT3A wording, fractional affordable‑unit calculations always rounded down; for example, a 35‑unit project produced 3 affordable units and one workforce unit under MBT3A but would generate four affordable and two workforce units under the underlying downtown rules. Board members said that discrepancy created a perverse incentive for developers to pick the zoning that required fewer affordable units.

Town staff said the town commissioned an updated economic feasibility analysis after spring town meeting, that the work completed on budget and that the town obtained pre‑clearance from the state review authorities named in the staff presentation (the EOHLC and the Attorney General’s office) for the drafting language. The Chair said the changes are being brought to fall town meeting as Article 4 and urged town‑meeting members to support the correction.

The board treated the session as a preview; no formal vote on the article was taken by the planning board at the meeting. The change will appear on the warrant at town meeting and proponents say it will keep inclusionary requirements consistent across downtown districts if town meeting approves it.