Split Lots: When One Zoning Lot Sits in Two Districts

Zoning district boundaries follow streets where they can, but they also run along mid-block lines — commonly at a stated depth from the avenue, so the commercial strip along the front of the block gives way to the residential district behind. Commercial overlays are mapped the same way, reaching a fixed depth into residence districts. Rezonings add more edges: every boundary a map amendment draws has two sides, and lots do not rearrange themselves to match. The result is a steady population of lots that live in two regulatory worlds at once.

The Resolution's split-lot provisions start from a strict premise: the district boundary means what it says, and each portion of the lot is governed by the rules of the district it sits in. Floor area computes per portion — the commercial portion's area times its ceiling, the residential portion's area times its own — and uses are similarly confined: the district line runs through the lot, and what may occupy each side follows its own use rules. Limited flexibility provisions permit modest adjustments near the boundary in defined circumstances, but they are exceptions with conditions, not a general license to average the two districts.

For arithmetic, an illustration: a lot with sixty percent of its area on one side of the line and forty on the other carries a floor-area budget that is the weighted sum of two separate calculations — not the whole lot times either district's number, and not the whole lot times a blend.

A building may straddle the boundary, but it must reconcile with both regimes: each portion's envelope, each portion's use rules, each portion's parking and loading logic. Designs tend to respond by putting each program where its district allows it — retail toward the avenue portion, residential behind — with the section of the building changing where the line crosses. Filing is correspondingly heavier: the plans must demonstrate compliance portion by portion, and errors about where the line actually falls are errors about everything downstream.

Everything in a split-lot analysis inherits from one measurement: where the boundary crosses the lot, and how much area falls on each side. That is a parcel-geometry question — the mapped boundary against the lot's recorded shape — and neighborhood intuition is useless for it. PearlAudit resolves district membership against the lot's actual geometry: a divided lot's report carries each district with its portion share, and the rule analysis runs per portion rather than pretending the lot is whole. That is the honest arithmetic; anything else is an average of two laws that each apply in full.