subdivision design converting raw land into saleable lots and desirable communities
Post on 23-Dec-2015
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Today’s Agenda
• What is a subdivision?– Regulatory requirements– Qualitative standards
• Subdivision layout process
• Design concepts
• Case study example
What is a subdivision?
• Conversion of a land parcel from its natural or previous state to:
• Legal entity, where lot ownership can be transferred
• Profit venture, where development costs can be recouped through lot sales
• Urban place, where neighborhood roots can be developed
Each Lot Must Have:
• Minimum size (sq. ft.)
• Minimum road frontage
• Provision for utilities– Water/sewer or well/septic– Electricity, phone, gas, cable, etc.
• Buildable area/feasible structure location– Meeting setbacks, buffers– Respecting constraints (slopes, soils, wetlands)
Subdivision Approval Process
• Sketch plan review– Feedback on type (major/minor), regulatory fit
• Preliminary plat review– Checks on roads, utilities, lots, etc.
• Final plat submission– Install improvements or post bond– Recorded in land and tax records
What is a Good Subdivision
• Creates desirable social patterns
• Respects natural environment
• Provides efficient utility services
• Ensures accessibility (car, bike, pedestrian)
• Builds safe roads
• Minimizes cut and fill
• Seeks pleasant aesthetics
Elements of Success: 3 Scales
• Housing cluster or block – Access, parking, yards
• Neighborhood– Road systems– Open space network
• Community– Connectivity– Activity centers
Building a Sense of Place
• Theme or big idea (e.g., walkable neighborhood)
• Amenity location (e.g., central park, pool)
• Unique landscape (e.g., native plants, oaks)
• Architectural style (e.g., neotraditional)
• Site graphics (e.g., entry sign, st. signs)
Subdivision Layout Process• Regulations (density,
lot size, open space, utilities, etc.)
• Average/minimum lot sizes
• Site analysis• Road access• Internal roads (topo,
block layouts)
• Lot layout (rectangles, short side to st., build. area, n/s orientation, no double frontage)
• Open space, amenities• Paths, sidewalks• Utilities/storm water • Vegetation & slopes• Refine alternatives
Open Space Subdiv. Design-1
• Identify open space areas– Primary conservation: wetlands, floodplains,
steep slopes– Secondary conservation: sensitive, scenic,
unique uplands
• Locate house sites– Maximum view lots, abut open space, min. lot
width
Open Space Subdiv. Design-2
• Design road & trail alignments– Level or rolling areas– Avoid wetlands, habitats– Minimize road length, cost, dead ends, long
straight streets
• Draw in lot lines– Use off center, up front houses for larger side &
back yards
Subdivision Street Concepts
• Curvilinear: naturalistic, organic– Source: Frederick Law Olmsted– Auto oriented street standards– Examples: Treyburn, Gov. Club, The Oaks
• Neo-traditional: geometric, grids, diagonals– Source: Andres Duany, Peter Calthorpe– Pedestrian/transit/auto networks– Examples: Seaside, Washington, South. Village
Subdivision Street Concepts-2
• Urban cluster: geometric, central courts– Source: Clarence Stein, Henry Wright– Separation of auto service lanes & pedestrian
paths and open spaces– Example: Radburn, N.J.
Basic Housing Layout Concepts
• Single family detached &/or attached– Block: face street, w/ alleys (5-10 du/ac)– Cluster: face st. or green, w/ alleys (4-6 du/ac) – Parking court: face court (10-12 du/ac)– Eyebrow: face island (3.5-6 du/ac)
• Multi-family– Quadrangle: face court & parking (14-16 du ac)– Parking court: face parking (15-18 du/ac)
Case study example
• Difficult hilly site
• 1st layout disregarded drainage ways, slopes
• 2nd layout left drainage ways open, followed natural contours with road
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