§ 18.30.070 — Basements

A. Purpose. The purpose of this Section is to provide standards for basements, lightwells, stairwells, and other excavated features. B. Allowable Basement Area. Basements shall not extend beyond the structure footprint and are not allowed below any portion of a structure that extends into required setbacks. C. Inclusion as Gross Floor Area. Basements shall not be included in the calculation of gross floor area, provided that the: 1. Basement area is not deemed to be habitable (i.e., crawlspace); or 2. Basement area is deemed habitable space, but the finished level of the first floor is no more than three feet above the grade around the perimeter of the structure foundation. Grade is measured at the lowest point of an adjacent ground elevation prior to grading, filling, or finished grade, whichever is lower. D. Lightwells, Stairwells, and other Excavated Features. Excavated features shall not affect the measurement of the grade for determining gross floor area, so long as the excavated features meet the following standards: 1. Lightwells, stairwells, and similar excavated features along the perimeter of the basement shall not affect the measurement of grade provided that: a. Features are not located in the front of the structure; b. Features shall not exceed three feet in length; c. Cumulative length of all features does not exceed 30 percent of the perimeter of the basement; d. Features do not extend more than three feet into a required side setback or no more than four feet into a required rear yard setback, except when a side yard setback is less than six feet, then features shall not encroach closer than three feet from the adjacent side parcel line; e. Cumulative length of any features or portions of features that extend into a required side or rear yard setback do not exceed 15 feet in length; f. Property owner shall provide documentation to the Planning Division prior to the issuance of a Building Permit that any features or portions of features that extend into a required side or rear yard setback, and how the projections will affect any mature trees on the parcel or abutting parcels; and g. Features have either a drainage system that meets the requirements of the Public Works Department or are substantially sheltered from the rain by a roof overhang or canopy of a permanent nature. 2. Below-grade patios, sunken gardens, or similar excavated areas along the perimeter of the basement that exceed the dimensions allowed in Subsection (1) above, are allowed and shall not affect the measurement of the basement or the grade provided that: a. Areas are not located in the front of the structure; b. All areas combined do not exceed two percent of the area of the parcel or 200 square feet, whichever is greater, that each area does not exceed 200 square feet, and that each area is separated from another by a distance of at least 10 feet. Areas devoted to stairway access shall not be included in the 200 square foot limitation. c. Cumulative length of any excavated area that extends into a required side or rear yard setback does not exceed 15 feet; d. Property owner shall provide documentation to the Planning Division prior to the issuance of a Building Permit that any features or portions of features that extend into a required side or rear yard setback will not affect any mature trees on the parcel or abutting parcels; e. Features are sheltered from the rain by a roof overhang or canopy of a permanent nature; and f. Any roof overhang or canopy allowed in subsection (e) shall comply with the requirements in Section 18.30.020 (Permitted Projections in Required Setbacks). -This page intentionally left blank-