Site Planning and Land Use
Site Planning and Land Use
Site planning integrates land use regulations, physical site constraints, and project program. Candidates must understand zoning ordinances (allowed uses, density, setbacks, height limits, floor-area ratio), the general plan or comprehensive plan, and how these shape development capacity. Key concepts include: development yield (dwelling units per acre, building coverage, impervious coverage limits), setbacks and buffers, parking requirements, access and circulation (driveway spacing, sight distance, emergency access), and environmental constraints (slope, floodplain, wetlands, habitat).
A common trap is confusing gross vs. net density: gross density uses total site area, while net density excludes right-of-way and non-developable land. Questions may ask for the number of units allowed given a density and site area; always check whether the density is gross or net and whether any overlay zones or bonuses apply. Another trap is setback measurement: front setbacks are typically measured from the property line or right-of-way, and corner lots have two front setbacks. Also, floor-area ratio (FAR) is the ratio of building floor area to lot area; do not confuse it with building coverage (footprint area).
Worked example: A 10-acre site is zoned for 8 units per gross acre with a 20% open space requirement. How many units are allowed? First, compute gross units: 10 acres × 8 units/acre = 80 units. Open space does not reduce the unit count unless the ordinance explicitly ties density to net area; here density is based on gross area, so 80 units are allowed. However, if the ordinance requires 20% open space, the buildable area is 8 acres, but density remains 80 units because it's gross. Always read the density basis carefully.
Rule of thumb: For quick site capacity, use the “10% rule”: approximately 10% of a site is typically lost to right-of-way and another 10% to stormwater management, so developable area ≈ 80% of gross site area. This helps sanity-check calculations.