1. Converting Raw Land into Saleable Lots and Desirable Communities
Subdivision Design
Converting Raw Land into Saleable Lots and Desirable Communities

2. Today’s Agenda What is a subdivision? Subdivision layout process
Regulatory requirements
Qualitative standards
Subdivision layout process
Design concepts
Case study example

3. 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

4. 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)

5. 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

6. Sketch Plan

7. Preliminary Plat

8. Final Plat

9. 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

10. Elements of Success: 3 Scales
Housing cluster or block
Access, parking, yards
Neighborhood
Road systems
Open space network
Community
Connectivity
Activity centers

11. 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)

12. Central Commons as a Big Idea

13. Subdivision Layout Process
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
Regulations (density, lot size, open space, utilities, etc.)
Average/minimum lot sizes
Site analysis
Road access
Internal roads (topo, block layouts)

14. 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

15. Site Before Development

16. Traditional Yield Plan

17. Primary Conservation Areas

18. Secondary Conservation Areas

19. 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

20. Adding Houses, Roads, Trail

21. Adding Lot Lines

22. 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

23. 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.

24. Curvilinear, Grid, & Cluster

25. 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)

26. Block Layout

27. Cluster Layout

28. Parking Court Layout

29. Eyebrow Layout

30. Multi-family Quadrangle

31. Multi-family Parking Court

32. Case study example Difficult hilly site
1st layout disregarded drainage ways, slopes
2nd layout left drainage ways open, followed natural contours with road

33. Case Study Site Analysis

34. Original Plan--Too Costly

35. Better Plan: Respects Contours