skill / Zoning Analysis

Zoning Analysis: New York City, NY

A Claude Code skill that calculates buildable envelopes for any lot in New York City — FAR, height limits, setbacks, yards, permitted uses, parking, and bonuses using PLUTO data and the NYC Zoning Resolution.

zoning nyc analysis
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What it does

Type /zoning-analysis-nyc with an address, BBL (Borough-Block-Lot), or BIN. The skill queries the PLUTO dataset via the NYC Open Data API, then walks through the Zoning Resolution to calculate the full buildable envelope — including the edge cases that trip up even experienced professionals.

Install

Claude Desktop:

  1. Open Customize → Browse plugins
  2. Click + → Add marketplace from GitHub
  3. Enter AlpacaLabsLLC/skills-for-architects
  4. Install the Zoning Analysis plugin

Claude Code (terminal):

claude install github:AlpacaLabsLLC/skills-for-architects/02-zoning-analysis

Usage

/zoning-analysis-nyc 250 Hudson St, New York NY

By BBL:

/zoning-analysis-nyc 1-00578-0047

What it calculates

  • FAR by use type — residential, commercial, community facility
  • Height & setback — base height, building height, sky exposure plane
  • Yards & coverage — front, side, rear yards, lot coverage
  • Permitted uses — by use group
  • Parking requirements — post-City of Yes rules
  • Bonuses & incentives — Inclusionary Housing, UAP, public plaza
  • Development scenarios — maximum floor area under varying bonus assumptions

What it handles

  • Split zones (lots straddling two or more districts)
  • Contextual districts (A/B/D/X suffix rules)
  • Commercial overlays
  • Special purpose districts
  • Waterfront overlays
  • Quality Housing program (optional height factor and base/tower)
  • City of Yes for Housing Opportunity provisions (December 2024)

Data sources

  • NYC PLUTO dataset (Socrata Open Data API)
  • NYC Zoning Resolution
  • NYC Department of City Planning
  • ZoLa (zola.planning.nyc.gov)

Sample output

Generated from: /zoning-analysis-nyc 250 Hudson St, New York NY

# Zoning Analysis — 250 Hudson Street, Manhattan

## Lot Summary

| Parameter | Value |
|-----------|-------|
| BBL | 1-00578-0047 |
| Address | 250 Hudson Street |
| Borough | Manhattan (New York County) |
| ZIP | 10013 |
| Lot Area | 21,862 SF |
| Lot Dimensions | ~170 ft × 130 ft (irregular) |
| Current Building Area | 340,618 SF |
| Current FAR (built) | 15.58 |
| Current Use | Office (Class O6) |
| Year Built | 1929 |
| Last Altered | 2011 |
| Number of Floors | 14 |
| Zoning Map | 12a |

## Zoning Classification

| Parameter | Value |
|-----------|-------|
| Primary District | M1-6 |
| Special District | HSQ (Special Hudson Square District) |
| Commercial Overlay | None |
| Limited Height | None |
| Contextual | Yes (via HSQ — C6-4A equivalent for residential) |
| Split Zone | No |
| Landmark | None |
| Historic District | None |

### Special Hudson Square District (HSQ)

The 2013 Hudson Square rezoning (ZR Article VIII, Chapter 8) overlays M1-6
and permits residential development using C6-4A bulk rules. The district
includes conversion restrictions to preserve commercial floor area in
qualifying buildings (>70,000 SF as of 3/20/2013).

250 Hudson Street is a **qualifying building** (340,618 SF). Residential
conversion requires CPC certification and a restrictive declaration.

## Bulk Parameters

### Floor Area

**For developments containing residences (C6-4A equivalent):**

| Use | Max FAR | Max Floor Area (SF) |
|-----|---------|---------------------|
| Residential | 9.0 | 196,758 SF |
| Commercial | 10.0 | 218,620 SF |
| Community Facility | 10.0 | 218,620 SF |

**For non-residential development (M1-6 base):**

| Use | Max FAR | Max Floor Area (SF) |
|-----|---------|---------------------|
| Commercial | 10.0 | 218,620 SF |
| Community Facility | 10.0 | 218,620 SF |
| Manufacturing | 10.0 | 218,620 SF |

The existing building at 340,618 SF (FAR 15.58) significantly exceeds the
10.0 FAR maximum. This is a pre-existing non-conforming condition —
grandfathered but cannot be enlarged.

### Height & Setback

| Parameter | Value |
|-----------|-------|
| Max Building Height | 290 ft (general) / 430 ft (Subdistrict A) |
| Base Height (min–max) | 60–85 ft (C6-4A, wide street) |
| Sky Exposure Plane | Starts at 85 ft, ratio 5.6:1 (wide street) |
| Street Wall | Required at street line (C6-4A residential) |
| Tapering | Above 230 ft: top 15% — each floor ≤90% of floor below |

### Yards & Coverage

| Parameter | Value |
|-----------|-------|
| Front Yard | None |
| Rear Yard | 20 ft (M1-6) or 30 ft (C6-4A residential) |
| Side Yards | None |
| Max Lot Coverage | No maximum (tower coverage rules apply above base) |

## Permitted Uses

**As M1-6 (non-residential):**
- Commercial: Use Groups 4–14, 16
- Community Facility: Use Groups 3–4
- Manufacturing: Use Groups 16–17
- Residential: NOT permitted under base M1-6

**As HSQ (with residential):**
- Residential: Use Group 2 — permitted via Special District
- Subject to qualifying building conversion restrictions

## Parking Requirements

Post-City of Yes (December 2024):

| Use | Requirement |
|-----|-------------|
| Residential | None (mandate eliminated) |
| Commercial | None (mandate eliminated) |
| Parking maximum | Manhattan Core — capped, not required |
| Loading | ~7 berths (based on ~340,000 SF) |
| Bicycle | 1 per DU (residential); 1 per 2,000 SF (office) |

## Bonuses & Incentives

| Bonus | Details |
|-------|---------|
| Inclusionary Housing | Available — Hudson Square is IH-designated |
| UAP (City of Yes) | +20% residential FAR for affordable housing |
| School exemption | Subdistrict A: school floor space exempt from FAR |

### UAP Calculation

| Scenario | Residential FAR | Floor Area (SF) |
|----------|----------------|-----------------|
| Base | 9.0 | 196,758 SF |
| With UAP (+20%) | 10.8 | 236,110 SF |
| UAP increment (must be affordable) | 1.8 | 39,352 SF |

## Restrictions & Special Conditions

- **Qualifying building:** Residential conversion requires CPC certification
  and restrictive declaration preserving commercial floor area.
- **Non-conforming FAR:** 15.58 built vs. 10.0 allowed. Cannot enlarge.
  Demolish-and-rebuild limited to 10.0 FAR.
- **PFIRM15 flag:** Lot flagged in preliminary flood maps. Verify with FEMA.

## Development Potential

### New Development (demolish and rebuild)

| Scenario | FAR | Floor Area (SF) | Est. Floors |
|----------|-----|------------------|-------------|
| As-of-right commercial | 10.0 | 218,620 SF | ~18 |
| As-of-right residential | 9.0 | 196,758 SF | ~16 |
| Residential with UAP | 10.8 | 236,110 SF | ~20 |
| Residential with IH bonus | Up to 12.0 | Up to 262,344 SF | ~22 |
| Community Facility | 10.0 | 218,620 SF | ~18 |

### Retain Existing Building

- Office (current): 340,618 SF grandfathered. No expansion.
- Residential conversion: CPC certification required. Must preserve
  commercial floor area. Significant constraint.
- Office-to-residential (City of Yes): Eligible (built 1929, before
  1991 cutoff). HSQ qualifying building rules may supersede.

## Buildable Envelope

### Plan View

                        ← 170 ft →
             ┌──────────────────────────────┐
             │         20 ft rear yard      │  ↑
             │  ┌────────────────────────┐  │  |
             │  │                        │  │  |
             │  │    BUILDABLE ZONE      │  │  |
             │  │    170 ft × 110 ft     │  │  130 ft
             │  │    ~18,700 SF          │  │  |
             │  │                        │  │  |
             │  │                        │  │  |
             │  └────────────────────────┘  │  ↓
             └──────────────────────────────┘
                  HUDSON ST (wide street)
                  ← no front setback →

No side yards (not adjacent to R district). Rear yard 20 ft (M1-6)
or 30 ft if residential (C6-4A). Irregular lot — verify with survey.

### Section View (Hudson St)

    290 ft ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ max height (HSQ general)
           │                ╱
           │              ╱  sky exposure
           │            ╱    plane (5.6:1)
           │          ╱
     85 ft ├────────┤ ← setback line
           │        │
           │        │ streetwall / base
           │        │ (60–85 ft)
           │        │
    ───────┴────────┴─────────────────── street
                HUDSON ST (wide)

    Existing: 14 floors (~180 ft), fits within envelope

If in Subdistrict A, max height is 430 ft with tapering (top 15%:
each floor ≤90% of floor below).

## Caveats

- Based on PLUTO v25v4 and ZR as of March 2026.
- PLUTO shows residfar=0 because base M1-6 prohibits residential.
  The HSQ special district overrides this to 9.0 (C6-4A equivalent).
- Subdistrict boundaries should be verified on ZoLa.
- Qualifying building restrictions are legally complex — review
  ZR Section 88-11 with counsel before any conversion project.
- City of Yes provisions are phasing in. Confirm effective dates.
- This is not a substitute for professional zoning analysis or
  legal advice.