23.86.007

A. Gross floor area. Except where otherwise expressly provided in this Title 23 , gross floor area shall be as defined in Chapter 23.84A and as measured in this Section 23.86.007 . The following are included in the measurement of gross floor area in all zones: 1. Floor area contained in stories above and below grade; 2. The area of stair penthouses, elevator penthouses, and other enclosed rooftop features; 3. The area of motor vehicle and bicycle parking that is enclosed; and 4. The area of motor vehicle parking that is covered by a structure or portion of a structure containing enclosed floor area, excluding motor vehicle parking in Neighborhood Residential and multifamily zones that is only covered by one of the following: a. Projections containing enclosed floor area of up to 4 feet; or b. Projections containing enclosed floor area of up to 6 feet for the area of parking accessed from an alley and located directly adjacent to an alley. B. Net unit area. Where development standards refer to net unit area, net unit area shall be square feet of total floor area bounded by the inside surface of the perimeter walls of the unit, as measured at the floor line. Net unit area excludes spaces shared by multiple units and accessible to all building occupants such as common hallways or lobbies. Net unit area includes any walls internal to the unit. C. Underground floor area. Except as otherwise expressly provided in this Title 23 , if gross floor area in stories, or portions of stories, that are underground is exempted from a calculation, the amount of underground gross floor area exempted is measured as follows: 1. A story or portion of a story is considered underground if the ceiling above, or the roof surface if there is no next floor above, is at or below the abutting existing or finished grade, whichever is lower (See Exhibit A for 23.86.007 ). 2. To determine the amount of gross floor area that is underground: a. Determine the elevation of the ceiling of the underground story, or the roof surface if there is no next floor above the underground story; b. Determine the points along the exterior wall of the story where the ceiling elevation or roof surface elevation above intersects the abutting corresponding existing or finished grade elevation, whichever is lower; c. Draw a straight line across the story connecting the two points on the exterior walls; d. The gross floor area in stories, or portions of stories, that are underground is the area that is at or below the straight line drawn in subsection 23.86.007.C.2.c. Exhibit A for 23.86.007 Underground floor area D. Pursuant to subsections 23.44.050.C, 23.45.510.D, and 23.47A.013.B, and Section 23.48.020 , for certain structures in Neighborhood Residential, multifamily, commercial, and Seattle Mixed zones, portions of a story that extend no more than 4 feet above existing or finished grade, whichever is lower, are exempt from calculation of gross floor area. The exempt gross floor area of such partially below-grade stories is measured as follows: 1. Determine the elevation 4 feet below the ceiling of the partially below-grade story, or 4 feet below the roof surface if there is no next floor above the partially below-grade story; 2. Determine the points along the exterior wall of the story where the elevation determined in subsection 23.86.007.D.1 intersects the abutting corresponding existing or finished grade elevation, whichever is lower; 3. Draw a straight line across the story connecting the two points on the exterior walls; and 4. The gross floor area of the partially below-grade story or portion of a partially below-grade story is the area of the story that is at or below the straight line drawn in subsection 23.86.007.D.3, excluding openings required by the Building Code for egress. (See Exhibit B for 23.86.007 .) Exhibit B for 23.86.007 Floor area for partially below grade stories for certain structures in Neighborhood Residential, multifamily, commercial, and Seattle Mixed zones E. Public rights-of-way are not considered part of a lot when calculating FAR or, in downtown and SM-SLU zones, when calculating gross floor area allowed for residential development not subject to FAR. If dedication of right-of-way is required as a condition of a proposed development, the area of dedicated right-of-way is included in these calculations. F. If a lot is in more than one zone, the FAR limit for each zone applies to the portion of the lot located in that zone, except that if the sole difference between the zoning designations for portions of a lot is the base FAR, allowable floor area based on the calculations for the separate portions of the lot may be provided on the lot, and except that, if both zones are LR zones or both zones are either C or NC zones, then the allowed total floor area may be located anywhere on the lot. G. In SM-SLU zones, the lot area used to calculate the gross floor area (GFA) allowed for structures or portions of structures subject to an FAR limit on sites that include a residential tower shall be based on the area of the lot excluding the lot area required for tower development (see Exhibit C for 23.86.007 ) as follows: (Lot area - Area required for tower development) × FAR = Allowed GFA Exhibit C for 23.86.007 Lot Area Used to Calculate Gross Floor Area H. Measuring the area of motor vehicle parking. For the purposes of subsection 23.86.007.A.4, the "area of motor vehicle parking" shall include parking aisles, maneuvering space, and any adjacent areas physically accessible to vehicles, but shall not include driveways. Areas that are separated from all parking stalls by a garage door shall be considered part of the driveway and not part of the area of motor vehicle parking. (Ord. 127376 , § 93, 2025; Ord. 126855 , § 77, 2023; Ord. 126682 , § 12, 2022; Ord. 126509 , § 94, 2022 [zone name change]; Ord. 126157 , § 55, 2020; Ord. 125854 , § 10, 2019; Ord. 125791 , § 111, 2019; Ord. 125603 , § 81, 2018; Ord. 125272 , § 69, 2017; Ord. 124883 , § 19, 2015; Ord. 124378 , § 97, 2013; Ord. 123564, § 13, 2011; Ord. 123495, § 95, 2011; Ord. 115326, § 37, 1990; Ord. 113892, § 9, 1988; Ord. 112519, § 52, 1985; Ord. 112303, § 25, 1985)