Title 17C Land Use Standards
Chapter 17C.111 Residential Zones
Section 17C.111.210 Density
Purpose.
The number of dwellings per unit of land, the density, is controlled so that housing can match the availability of public services. The use of density minimums ensures that in areas with the highest level of public services, the service capacity is not wasted and that the City’s housing goals are met.
Unless specifically exempted, all residential development shall meet the minimum and maximum densities provided in Table 17C.111.205-1.
Gross Density Used.
The calculation of density for a subdivision or residential development is based on the total (gross) area of the subject property.
Critical Areas May Be Subtracted.
Land within a critical area (see definitions under chapter 17A.020 SMC) may be, but is not required to be, subtracted from the calculation of density.
Right-of-Way May Be Subtracted.
Land dedicated as Right-of-Way may be, but is not required to be, subtracted from a calculation of density.
Numbers Rounded Up.
When the calculation of density results in a fraction, the density allowed or required is rounded up to the next whole number. For example, when a calculation results in 4.35 units, the number is rounded up to five units.
Formula.
The following formula is used to determine the maximum number of units allowed or the minimum number of units required on the site:
Square footage of site, less any land within a critical area or dedicated to right-of-way, divided by the square footage of one acre (43,560 square feet), multiplied by the density number from Table 17C.111.205-1 equals maximum number of units allowed or minimum number of units required.
Example of determining the minimum number of units with a minimum density of 4 units/acre on a 135,036 square foot (3.1 acre) site:
( 135,036 square ft / 43,560 square ft/acre ) * 4 units/acre = 12.4 units (rounded up to 13 units)
Example of determining the maximum number of units with a maximum density of 20 units/acre on a 112,400 square foot (2.58 acre) site encumbered by 21,780 square feet (0.5 acre) of Critical Areas (see Title 17E):
[( 112,400 square feet – 21,780 square feet ) / 43,560 square ft/acre ) * 20 units/acre = 41.6 units (rounded up to 42 units]
If this formula results in a decimal fraction, the resulting number of units allowed is rounded up to the next whole number.
Land Division in R1 or R2 Zones.
If a land division is proposed in an R1 or R2 zone, the calculation of density shall count one lot as one dwelling unit.
Exceptions to Maximum Density Limits.
Development Less Than Two (2) Acres.
If the development site excluding any land within a critical area is two (2) acres or less in area, the maximum density standards shall not apply. Proposed new Right-of-Way may also be subtracted from the development site.
Middle Housing Allowance.
Notwithstanding any density maximum resulting from a density calculation, any combination of Middle Housing types identified under SMC 17A.020.130(J) shall be allowed on a lot up to six total units, including Accessory Dwelling Units. Such development shall still be subject to other site development standards which may limit the total amount of achievable development on the site.
Exceptions to Minimum Density Requirements.
Construction on Existing Legal Lots.
Except as provided in subsection (K), when renovation or new construction is proposed on an existing legal lot in the RA, R1, or R2 zones, minimum density shall not apply.
Land Divisions with Existing Structures.
When a land division is proposed on a lot below the minimum density and with an existing dwelling unit, any new lots created shall meet these density requirements. A lot which retains an existing primary structure may continue its nonconforming density.
Nonconforming Situations.
A site with pre-existing development may not move out of conformance or further out of conformance with the density standards, including sites in the RA, R1, and R2 zones (regardless of whether a land division is proposed).
Transfer of Density.
Density may be transferred from one site to another subject to the provisions of chapter 17G.070 SMC, Planned Unit Developments.
Other Standards Apply.
The number of units allowed or required on a site is based on the presumption that all site development standards will be met. A calculation of maximum allowable density does not ensure the maximum number is achievable under other standards and regulations that govern site development.
Date Passed: Monday, January 27, 2025
Effective Date: Thursday, March 6, 2025
ORD C36629 Section 3
