Zoning and Codes Skill

This skill provides comprehensive zoning analysis and form-based code generation capabilities for urban design and masterplanning projects. It covers the full spectrum of zoning approaches from conventional Euclidean zoning through transect-based SmartCode, and provides detailed workflows for translating design intent into enforceable regulatory language. The skill draws from the SmartCode, Miami 21, Denver Form-Based Code, and international best practices in development regulation.

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1. Zoning System Types

Use the following comparison matrix to select the appropriate zoning approach for a given project context. Each system has distinct strengths and is suited to different planning objectives.

Comparison Matrix

Type	Primary Controls	Strengths	Weaknesses	Best For
Euclidean	Use categories (residential, commercial, industrial) + dimensional standards (setback, height, lot size, FAR)	Simple to administer; predictable outcomes; well-understood by developers and communities; extensive legal precedent	Rigid separation of uses enforces automobile dependence and sprawl; does not address building form or public realm quality; encourages lowest-common-denominator development	Stable suburban areas; low-density residential neighborhoods; industrial zones; contexts where predictability is the primary goal
Performance	Impact metrics (traffic generation, noise levels, shadow/daylight access, stormwater runoff, air quality emissions)	Highly flexible; focuses on outcomes rather than prescriptions; encourages innovation in design solutions; can accommodate unforeseen uses	Complex to administer and enforce; requires technical expertise for review; unpredictable physical outcomes; challenging for community members to understand	Mixed-use areas where impact matters more than form; transitional zones between incompatible uses; innovation districts; areas with complex environmental constraints
Form-Based	Building form (height, setback, coverage, FAR), frontage types, building types, public space standards	Produces predictable physical form and high-quality public realm; enables mixed-use by right; regulates what matters most to communities (physical character); illustrated and accessible	Requires design expertise to draft and administer; less familiar to many planning departments; can be perceived as overly prescriptive for building design; initial adoption requires education	New development and infill projects; downtown revitalization; transit-oriented development; areas where physical character is the primary concern; urban renewal zones
Transect-Based (SmartCode)	Rural-to-urban gradient zones (T1-T6) with calibrated standards for each zone; integrates thoroughfare, civic space, and building standards	Holistic and context-sensitive; addresses the full range of human settlement patterns; internally consistent; treats urbanism as an ecology; comprehensive framework	Requires paradigm shift from conventional zoning thinking; initial calibration to local context is labor-intensive; may not fit jurisdictions with highly irregular development patterns	Comprehensive plan implementation; greenfield master-planned communities; complete code replacements; jurisdictions ready for a fundamentally different approach to regulation
Hybrid	Combination of two or more approaches (e.g., form-based for downtown + Euclidean for suburban residential + performance for industrial/environmental overlay)	Balanced approach; can tailor regulation to distinct character areas; pragmatic; easier political adoption by preserving familiar systems where they work	Can be complex to navigate; risk of internal contradictions between systems; may confuse applicants moving between zones with different regulatory logic	Most real-world applications; jurisdictions transitioning from Euclidean to form-based; cities with diverse character areas requiring different regulatory approaches

Selection Decision Tree

1. Is the project a comprehensive code replacement for an entire jurisdiction? --> Consider Transect-Based (SmartCode)
2. Is the project focused on a specific plan area (downtown, corridor, TOD)? --> Use Form-Based Code for the plan area
3. Does the area have complex environmental constraints (floodplain, noise, contamination)? --> Layer Performance standards as an overlay
4. Are existing suburban residential areas stable and not targeted for change? --> Retain Euclidean zoning for those areas
5. For most real-world jurisdictions --> Use a Hybrid approach combining the above as appropriate

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2. Transect Zone Specifications

The Transect is a cross-section of the human habitat ranging from the most natural (T1 Natural Zone) to the most urban (T6 Urban Core Zone). Each zone has a distinct character defined by calibrated standards for density, building form, frontage, street type, and permitted uses. The following table provides complete specifications for all six zones plus Special Districts (SD).

Complete T1-T6 Parameter Table

Parameter	T1 Natural	T2 Rural	T3 Sub-Urban	T4 General Urban	T5 Urban Center	T6 Urban Core
Character	Lands in a natural or wilderness condition, including water bodies and wetlands	Sparsely settled lands in open or cultivated state, woodland, grassland, agricultural	Low-density residential with deep setbacks, landscaped yards, detached buildings	Medium-density mixed residential and commercial with shallow setbacks, defined streetwall	Higher-density mixed-use with ground-floor retail, consistent streetwall, active frontage	Highest density and tallest buildings, greatest variety of uses, civic significance
Density (DU/ha)	0 (conservation)	0.5-2.5	5-12	12-25	25-60	60-150+
Building Height (stories)	N/A	1-2	1-3	2-5	4-8	6-30+ (varies by district)
Building Height (meters max)	N/A	9	12	18	28	Per specific district (typically 40-120)
Setback Front (min-max)	N/A	10-30m	5-10m	2-5m	0-3m	0-2m
Setback Side (min)	N/A	5-10m	3-5m	0-3m	0m	0m
Setback Rear (min)	N/A	10-20m	6-10m	3-6m	3-6m	3-6m
Lot Coverage (max %)	0-5%	10-20%	30-50%	50-70%	70-90%	80-100%
FAR (max)	N/A	0.1-0.3	0.3-0.8	1.0-2.5	2.5-5.0	5.0-15.0+
Frontage Type	N/A	Fence, hedge, naturalistic	Porch, fence, naturalistic	Stoop, dooryard, forecourt, porch	Shopfront, gallery, arcade, terrace	Shopfront, gallery, arcade
Building Type	N/A	Estate house, agricultural building, accessory dwelling	Detached house, cottage, duplex, villa, accessory dwelling	Rowhouse, townhouse, duplex, small apartment, live-work	Mid-rise apartment, mixed-use building, liner building	Tower, mid-rise, high-rise, civic building
Parking Requirements	N/A	On-site, no minimum	1-2 spaces/DU, on-site, driveway	0.5-1.5 spaces/DU, rear-loaded garages, shared lots	No minimum or 0.5/DU max, structured parking required above threshold	No minimum, structured or underground only
Open Space (min %)	95-100%	70-90%	40-60%	20-40%	10-20%	5-15% (may include rooftop)
Street Type	Trail, path	Rural road, rural avenue	Residential street, yield street	Avenue, neighborhood street, commercial street	Boulevard, avenue, commercial street	Boulevard, avenue, passage, alley
Permitted Uses	Conservation, recreation, agriculture	Agriculture, single-family residential, bed-and-breakfast, stables	Single-family, duplex, small office, daycare, small civic	Residential (all types), office, retail (<500 sqm), restaurant, civic, live-work	All residential, all retail, office, hotel, entertainment, civic, institutional	All uses permitted; highest-intensity commercial, office, institutional, residential
Civic Space Type	Nature preserve, greenway, wildlife corridor	Greenway, park, playground	Green, playground, community garden, pocket park	Square, plaza, playground, community garden	Plaza, square, urban park, promenade	Plaza, civic plaza, urban park, promenade, passage

Transect Zone Character Descriptions

T1 Natural Zone: Lands approximating or reverting to a wilderness condition, including lands unsuitable for settlement due to topography, hydrology, or vegetation. These are permanently protected areas that provide ecosystem services (water filtration, carbon sequestration, biodiversity habitat, flood control) and recreational value. No buildings except minor structures for conservation management and passive recreation (trails, observation platforms, restrooms).

T2 Rural Zone: Sparsely settled lands in open or cultivated state. These include woodland, agricultural land, grassland, and scattered buildings. The landscape is the dominant element; buildings are subsidiary. Typical settlement includes farmsteads, rural estates, and very small hamlets. Roads are typically two-lane without curbs, with open swales for drainage. The boundary between T2 and T3 is one of the most important in the transect, as it defines the edge of the neighborhood.

T3 Sub-Urban Zone: Low-density residential areas with predominantly detached buildings set back from tree-lined streets. Yards and landscaping are significant elements of the streetscape. Blocks are larger (150-250m) and streets are curvilinear or grid. This is the typical post-war suburban condition, but the transect version emphasizes connectivity, sidewalks, street trees, and proximity to neighborhood centers.

T4 General Urban Zone: The workhorse zone of a walkable neighborhood. Medium-density, mixed-use (by right), with a defined streetwall of moderate height (2-5 stories). Buildings have shallow front setbacks (2-5m) and form a continuous or near-continuous street edge. Ground floors may be residential or commercial depending on location. Streets are well-connected in a grid or modified grid, with on-street parking, street trees, and sidewalks on both sides.

T5 Urban Center Zone: The main street, town center, or downtown of a neighborhood, district, or small city. Higher density, wider variety of uses, more active ground floors, and taller buildings than T4. The streetwall is consistent and buildings are built to or near the front lot line. Ground floors are predominantly commercial (retail, restaurant, service). Upper floors are residential, office, or hotel. Parking is structured or underground, never surface lots facing the street.

T6 Urban Core Zone: The highest-intensity zone, found in city centers and major regional downtowns. Towers and high-rise buildings of significant height. Maximum variety and intensity of uses. Civic buildings and institutions of regional significance. Major transit infrastructure (rail stations, bus terminals). Public spaces are formal and hardscaped (plazas, civic squares, promenades). This zone typically applies only in the largest cities and in very limited geography.

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3. Form-Based Code Elements

A form-based code consists of several integrated components that work together to regulate the physical form of development. Each component addresses a distinct aspect of the built environment.

3.1 Regulating Plan

The regulating plan is the coded map that designates transect zones, civic space locations, special district boundaries, and thoroughfare types for every parcel within the plan area. It is the spatial expression of the code and the primary reference document for any applicant.

• Maps transect zones (T1-T6) to specific parcels or blocks
• Identifies mandatory building frontage lines (build-to lines)
• Designates required ground-floor retail frontages
• Locates civic space reservations (plaza, green, park)
• Shows thoroughfare types for every street segment
• Identifies special districts with unique standards (civic, waterfront, transit, historic)
• May include sub-area plans for complex sites

3.2 Building Form Standards

Building form standards regulate the physical envelope and configuration of buildings. These are the core of the form-based code and replace the bulk and dimensional standards of conventional zoning.

• Height: maximum stories and meters, measured from grade to highest occupied floor (or roof peak, depending on code), with exceptions for mechanical equipment, elevator overruns, parapets (typically +1.5m), and architectural features (spires, cupolas)
• Setback / Build-to Line: front setback is typically expressed as a build-to line (BTL) with a required percentage of building facade that must be located at the BTL (typically 70-90% in urban zones)
• Coverage: maximum building footprint as percentage of lot area
• FAR: maximum ratio of total floor area to lot area, with rules for calculation (e.g., structured parking excluded, mechanical rooms excluded, balconies excluded if open)
• Building Type: the permitted physical configurations (detached house, rowhouse, apartment building, mixed-use building, tower, etc.), each with its own sub-standards
• Disposition: the placement of the building on the lot (edgeyard, sideyard, rearyard, courtyard) -- determines how the building relates to the street and to open space

3.3 Frontage Type Standards

The frontage is the interface between the building and the public realm. Frontage type standards regulate the configuration of the ground floor and the zone between the facade and the lot line.

Frontage Type	Description	Depth	Height	Applicability
Shopfront	Large glazed opening at ground level for retail display, with transom, signage band, and bulkhead; entrance recessed or flush	0-0.6m setback	Ground floor 4.0-5.0m clear	T4, T5, T6 - commercial streets, required retail frontages
Gallery	Colonnade or covered walkway attached to the building facade, extending over the sidewalk, supported by columns	2.4-3.6m depth	3.0-4.5m clear	T4, T5, T6 - commercial streets, especially in warm/rainy climates
Arcade	Covered walkway within the building volume (building overhangs the sidewalk at upper floors, ground floor is setback creating a covered passage)	2.4-3.6m depth	3.0-4.5m clear	T5, T6 - high-intensity commercial, transit corridors
Stoop	Elevated entry platform with stairs to the sidewalk, providing a semi-private transition zone between public sidewalk and private dwelling	0.6-1.8m depth, 1.2-2.4m wide	0.6-1.5m above sidewalk	T3, T4 - residential streets, rowhouses, townhouses
Porch	Covered, unenclosed room attached to the building facade, elevated above the sidewalk, providing a semi-public social space	1.8-3.0m depth	Full story height, 0.3-0.9m above grade	T3, T4 - residential streets, detached and semi-detached houses
Forecourt	A portion of the lot left open between the building facade and the lot line, creating a small semi-public court or garden	3.0-6.0m depth	N/A (open)	T3, T4, T5 - institutional buildings, apartments, restaurants
Common Yard	The building is set back substantially from the lot line, with the front yard functioning as a shared community green	5.0-10.0m depth	N/A (open)	T3 - residential clusters, co-housing, campus settings
Terrace	The building is set back from the lot line with an elevated terrace or platform in front, often with a retaining wall or balustrade at the sidewalk edge	1.2-3.0m depth	0.3-1.0m above sidewalk	T4, T5 - residential, mixed-use buildings on sloping sites
Dooryard	A shallow planted or paved area between the building facade and the sidewalk, defined by a low wall, fence, or hedge	0.6-2.4m depth	Fence/wall 0.3-1.2m	T3, T4 - residential streets, cottage and village contexts
Lightwell / Areaway	A below-grade court in front of the building, providing light and access to a basement level, protected by a railing or wall at sidewalk level	0.9-1.8m depth below grade	Railing 0.9-1.1m at sidewalk	T5, T6 - urban buildings with occupied basements

3.4 Public Space Standards

Public space standards regulate the design and programming of the civic realm, including parks, plazas, greens, squares, playgrounds, and community gardens.

Space Type	Typical Size	Character	Key Standards	Applicability
Plaza	0.1-0.5 ha	Hardscaped, formal, framed by building facades on at least two sides, civic or commercial focus	Min 50% hardscape, required seating (1 LF per 30 sqm), shade structures or trees on 30%+ of area, water feature or public art encouraged	T5, T6
Square	0.2-1.0 ha	Formal green, framed by streets and buildings on all four sides, civic focus with monument or fountain	40-60% planted, formal tree planting (allees, bosques), paths, benches, central feature	T4, T5, T6
Green	0.2-2.0 ha	Informal open lawn, naturalistic planting, passive recreation, visual relief	70%+ planted, informal tree clusters, open lawn for flexible use, minimal hardscape	T3, T4
Pocket Park	0.02-0.1 ha	Small intimate space on a single lot, seating, shade, respite from urban environment	Seating for 10-30 people, shade trees or structure, low maintenance planting, visible from street	T4, T5
Playground	0.1-0.5 ha	Dedicated play space for children, with equipment, safety surfacing, shade, seating for caregivers	Age-appropriate equipment (2-5 and 5-12 zones), safety surfacing (rubber, engineered wood fiber), shade 40%+, fencing where adjacent to traffic	T3, T4, T5
Community Garden	0.05-0.3 ha	Individual garden plots, shared tool shed, water supply, compost area, gathering space	Individual plots 3x6m typical, shared infrastructure, accessible paths, water supply, perimeter fencing, storage	T3, T4
Promenade	Linear, 4-8m wide	Formal linear walking path along a waterfront, park edge, or significant corridor	Min 4.0m clear width, benches every 30-60m, lighting, trees, separated from vehicles	T4, T5, T6

3.5 Thoroughfare Standards

Thoroughfare standards define the cross-section, character, and design parameters for every street type in the code. These replace conventional transportation engineering standards with context-sensitive designs.

• Each thoroughfare type gets a full cross-section specification (see the Street Design skill for detailed cross-section methodology)
• Thoroughfare types are assigned to the regulating plan by segment
• Standards cover: ROW width, travel lanes (number and width), parking (type and width), bike facilities, sidewalk zones, median, planting, lighting
• Typical thoroughfare types: boulevard, avenue, commercial street, neighborhood street, residential street, rear lane/alley, passage, shared street, path/trail

3.6 Signage Standards

Signage standards regulate the type, size, placement, and illumination of signs to ensure visual quality and consistency.

• Projecting signs: perpendicular to facade, max 0.6 sqm per sign, min 2.4m clearance above sidewalk, max projection 1.2m
• Wall signs: flat on facade, max 10% of facade area or 2.0 sqm (whichever is less in T3-T4, greater in T5-T6), letter height max 300mm (T4), 450mm (T5), 600mm (T6)
• Awning/canopy signs: text on valance only, max letter height 200mm
• Window signs: max 25% of window area, no flashing or animated
• Monument signs: ground-mounted, max 1.2m height (T3), 1.5m (T4), not permitted T5-T6
• Illumination: external illumination (gooseneck, wash) permitted all zones; internal illumination (backlit channel letters) permitted T5-T6 only; neon permitted T5-T6 only; no flashing, scrolling, or animated signs

3.7 Architectural Standards (Optional Companion)

Architectural standards are typically advisory (guidelines) rather than mandatory (code), but some form-based codes include mandatory provisions for key elements.

• Materials: primary facade materials (masonry, stucco, wood clapboard, metal panel); prohibited materials (EIFS below 2.4m, vinyl siding in T5-T6, exposed concrete block); material transitions at inside corners only (not outside)
• Fenestration: minimum ground-floor transparency (60-80% in T5-T6 shopfronts, 30-50% in T4), upper-floor window-to-wall ratio (20-40%), window proportions (vertical orientation preferred), prohibited: mirrored glass, all-glass curtain wall below T6
• Rooflines: flat roofs with cornice or parapet (T5-T6), pitched roofs 6:12 to 12:12 (T3-T4), roof material standards, mechanical screening required
• Color: typically advisory, may regulate in historic districts
• Parking structure facades: must be wrapped with habitable space on all street-facing facades, or designed with architectural facade treatment that conceals the parking structure

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4. Building Envelope Controls

Building envelope controls define the three-dimensional volume within which a building may be constructed. These are the most precise regulatory tools in a zoning code.

4.1 Height Controls

Parameter	Specification	Notes
Maximum height in stories	T3: 3, T4: 5, T5: 8, T6: varies (6-30+)	Story count is primary control in form-based codes
Maximum height in meters	T3: 12m, T4: 18m, T5: 28m, T6: varies	Measured from average grade at building perimeter to highest occupied floor ceiling
Ground floor minimum height	3.6m (commercial), 3.0m (residential)	Floor-to-floor, ensures future commercial conversion potential
Upper floor height range	2.7-3.6m floor-to-floor	Allows residential (2.7-3.0m) or commercial (3.3-3.6m)
Datum point	Average pre-development grade at front lot line	Prevents manipulation of grade to gain height
Mechanical exceptions	Elevator overruns, mechanical rooms, stair bulkheads: max +4.5m above roof, setback 3.0m from facade	Must be screened from view at street level
Parapet exception	Max +1.5m above roof height limit	Architectural element, not habitable
Architectural feature exception	Spires, cupolas, clock towers: max +6.0m, max 10% of roof area	Civic and institutional buildings primarily

4.2 Setback and Build-to-Line Controls

Parameter	T3 Sub-Urban	T4 General Urban	T5 Urban Center	T6 Urban Core
Front build-to line (BTL)	5-10m from ROW	2-5m from ROW	0-3m from ROW	0-2m from ROW
BTL compliance	50% of facade at BTL	70% of facade at BTL	80% of facade at BTL	90% of facade at BTL
Side setback (interior)	3-5m	0-3m	0m	0m
Side setback (street-facing)	3-5m	2-4m	0-3m	0-2m
Rear setback	6-10m	3-6m	3-6m	3-6m
Rear setback to alley	3m	1.5m	0m	0m

Build-to-line (BTL) is fundamentally different from a setback. A setback defines a minimum distance from which a building must be placed; a BTL defines a line at which the building facade must be placed. The BTL creates a consistent streetwall. The "compliance percentage" specifies how much of the lot width must have building facade at the BTL (the remainder may be recessed for courtyards, forecourts, or entries).

4.3 Lot Coverage

Maximum percentage of the lot area that may be covered by the building footprint:

• T3: 30-50% (significant open space on lot)
• T4: 50-70% (moderate open space)
• T5: 70-90% (minimal open space, may be on upper levels)
• T6: 80-100% (nearly full lot coverage, open space on rooftops or at upper setbacks)