Density Calculation Worksheet Erika Court Residential Density Calculations
18.715.020 Density Calculation
A. Definition of net development area. Net development area, in acres,
Buildable Land Area shall be determined by subtracting the following land area(s)from
Gross Area (SF) 145,869 the gross acres, which is all of the land included in the legal
Subtractions [§18.715.020.A] description of the property to be developed:
1. Sensitive Land Areas (n/a) 0 1. All sensitive land areas:
2. Park Dedications (n/a) 0 a. Land within the 100-year floodplain,
3. Public Rights-of-Way (actual) 29,850 I b. Land or slopes exceeding 25%,
c. Drainage ways, and
4. Private Street (n/a) 0 d. Wetlands,
5. Area for Existing House 17,695 e. Optional: Significant habitat areas, as designated
Subtotal:Subtractions[§18.715.020.A] 47,545 on the City of Tigard "Significant Habitat Areas Map";
Net Buildable Land Area 98,324 2. All land dedicated to the public for park purposes;
3. All land dedicated for public rights-of-way. When
Maximum Residential Units Calculation [§18.715.020.8] actual information is not available, the following formulas may
Net Buildable Land Area 98,324 be used:
a. Single-family development:allocate 20%of gross acreage,
(divide by) Minimum Lot Area in R-3.5 Zone 10,000 b. Multifamily development: allocate 15%of gross acreage or
Maximum Residential Units 9.832 deduct the actual private drive area;
plus 1 lot for existing house 10 4. All land proposed for private streets;and
Minimum Residential Units Calculation [§18.715.020.C] 5. A lot of at least the size required by the applicable base
Maximum Number of Units Allowed 10.000 zoning district, if an existing dwelling is to remain on the site.
(multiply by) 0.8 80% B. Calculating maximum number of residential units. To calculate the
maximum number of residential units per net acre, divide the
Minimum Residential Units 8.000 number of square feet in the net acres by the minimum number of
square feet required for each lot in the applicable zoning district.
C. Calculating minimum number of residential units. As required by
Section 18.510.040, the minimum number of residential units per net
acre shall be calculated by multiplying the maximum number of
units determined in Subsection B above by 80% (0.8). (Ord. 09-13)