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Subdivision Design. Converting Raw Land into Saleable Lots and Desirable Communities. Today’s Agenda. What is a subdivision? Regulatory requirements Qualitative standards Subdivision layout process Design concepts Case study example. What is a subdivision?.
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Subdivision Design Converting Raw Land into Saleable Lots and Desirable Communities
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)
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 Subdivision Layout Process
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