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The first hour of every feasibility study, made teachable. Pick a parcel and a teaching zoning district — front/side/rear setbacks, a height cap, a sky-exposure plane — and watch the legal BULK ENVELOPE get carved, one rule at a time. Tag the street edges and the envelope carves one rule at a time, so you can see which rule removed which volume. Then fill it: floor-to-floor, plate shape, a core you place yourself. Stack reads back gross floor area, the FAR you actually used against the FAR you're allowed, net-to-gross efficiency, core-to-floorplate ratio and a schematic unit count, and tells you which rule is actually binding — height or FAR, and by how much. The rule sets are INVENTED for teaching, not any real municipality's code, and this is not a compliance check. Client-side, no account.

Try the predict-first version ↗

Teaching rule sets — invented, not any municipality's code. Not a compliance check, not legal advice, not for permitting.

1 · Pick a parcel

3 · Pick a teaching district

These districts are INVENTED for teaching — every number is editable, none is any real municipality's code.

The house district: generous setbacks, a hard 35 ft cap. Here HEIGHT binds long before FAR does — you run out of sky with floor-area budget to spare.

Setbacks (carve)

Height (carve)

Sky-exposure plane (carve)

Budgets — never carved

FAR and coverage are spending limits the Phase 2 fill will draw down — they never change the envelope's shape.

2 · Tag the street edges

Click an edge to cycle its role: SIDE → FRONT → REAR. Front, side and rear setbacks apply to the edges you tag — corner lots take two fronts. Tag a FRONT and the envelope carves.

Parcel plan, north up: the lot outline with each edge labelled front, side or rear, a 10-foot reference grid, and the footprint polygon you are drawingSIDE · 50SIDE · 120SIDE · 50SIDE · 120N

Tag a street edge

Pick a parcel, then click an edge on the plan to tag it FRONT. The envelope carves as soon as one front edge is tagged, and every rule on the left re-carves it live.

Sources & methods
  • Teaching rule sets — invented, not any municipality's code. Not a compliance check, not legal advice, not for permitting.
  • Setbacks, the height cap and sky-exposure planes are exact half-plane geometry, solved on CONVEX parcels only — a re-entrant corner needs a straight-skeleton offset this tool doesn't have.
  • The envelope is sampled at floor levels (12 ft floor-to-floor): what you see is the union of the legal floorplates, not a smooth ruled surface. Honest for stepped-setback rules, still a sampling.
  • FAR and lot coverage are BUDGETS, never carves — the fill spends them and they never change the envelope's shape.
  • The yield is an AREA TAKEOFF, not a plan: a rule-of-thumb core (handbook-typical, UNVERIFIED — editable, never lift sizing), a schematic corridor band down the plate's long axis, and a flat structure percentage. The unit mix is a strip-and-slice count with no egress, light-and-air or accessibility logic.
  • Scoring: plan-IoU is set algebra; area and height land on Footprinter's shared log-scale bands (within ×1.25 = dead on, ×2, ×5, ×10). No AI judges anything here.