Corpus

Chapter 23.86 - MEASUREMENTS

Seattle Mun. Code — Chapter 23.86 - MEASUREMENTS
in effect

Seattle Mun. Code § 23.86.002 General provisions

A. For all calculations, the applicant shall be responsible for supplying drawings illustrating the measurements. These drawings shall be drawn to scale, and shall be of sufficient detail to allow verification upon inspection or examination by the Director. B. Fractions 1. Unless otherwise indicated, if any measurement technique for determining the number of items required or allowed, including but not limited to motor vehicle parking, or required trees or shrubs, results in fractional requirements, any fraction up to and including 0.5 of the applicable unit of measurement shall be disregarded and fractions over 0.5 shall require the next higher full unit of measurement. 2. If any measurement technique for determining required minimum or allowed maximum dimensions, including but not limited to height, setbacks, lot coverage, open space, building depth, parking space size, or curb cut width, results in fractional requirements, the dimension shall be measured to the nearest inch. Any fraction up to and including 0.5 of an inch shall be disregarded and fractions over 0.5 of an inch shall require the next higher unit. 3. When calculation of the number of dwelling units allowed results in a fraction of a unit, any fraction over 0.85 constitutes one additional unit. C. Where the location of a lot line varies depending on elevation, such as partial right-of-way vacations and dedications that include below-grade areas but exclude the area at ground level, development standards that rely on lot lines shall be based on the location of lot lines at grade. (Ord. 127376 , § 91, 2025; Ord. 125791 , § 110, 2019; Ord. 125603 , § 79, 2018; Ord. 124803 , § 7, 2015; Ord. 120117, § 58, 2000; Ord. 119242, § 11, 1998; Ord. 117263 70, 1994; Ord. 111390, § 49, 1983; Ord. 110381, § 1(part), 1982.)

Seattle Mun. Code § 23.86.004 Sign measurements.

A. Sign Area. 1. For a sign which is an independent structure, the entire visible surface of the sign, exclusive of support devices, shall be included in area calculations. Only one (1) face of a double-faced sign shall be counted. 2. For a sign painted or mounted directly on another structure, sign area shall be the area contained in the smallest rectangular area enclosing the graphic or worded message, measured by the projection of the legs of two (2) right angles that are placed at opposite corners of the graphic and/or worded message (Exhibit 23.86.004 A) 3. Where a background color different from that of the face upon which a sign is located is used as part of the sign, the entire background area shall be included in area calculations (Exhibit 23.86.004 B). 4. Only message-conveying text shall be included. Decorative graphics not conveying a readily apparent message are not counted in the area of the sign. 5. For the purposes of measuring sign area for signs regulated by Section 23.55.042 , signs adjacent to certain public highways, the following provisions shall also be used to calculate sign area: a. Where freestanding business signs and business signs on the face of a building are visible on the same premises, the sum of the area of both types of signs visible from any place on the traveled way shall not exceed the area permitted on the face of the building, except as provided for gas station signs and in subsection E1 of Section 23.55.042 . b. Where a multi-faced sign is used, the greatest area visible from any place on the traveled way shall be measured. 6. In major institution zones, when signs with and without size limits are combined, the portion of the sign to which a size limit applies shall not exceed the applicable limit. B. Number of Signs. In certain zones, the type and number of signs is determined by amount of frontage on public rights-of-way, except alleys. Frontage shall be measured as follows: 1. When only one (1) business establishment is located on a lot, or when determining the frontage of a multiple business center, frontage shall equal the length of the street property line(s) of the lot on which the business establishment or multiple business center is located (Exhibit 23.86.004 C). 2. When determining the frontage of a business establishment located in a multiple business center, the following method shall be used: a. Draw the least rectangle that encloses the portion of the principal structure in which the business establishment is located, as well as any area used for outdoor sales or outdoor display of rental equipment. b. Extend the sides of the rectangle to the property line(s) of the lot which abut a right-of-way, except an alley, and which are not blocked from the rectangle by another structure or portion of the structure (Exhibit 23.86.004 D). c. The lineal footage of the frontage between the extended sides of the rectangle shall be the frontage of the business establishment for purposes of measuring the number and type of permitted signs. C. Dispersion Standards for Off-premises Signs. 1. Where linear dispersion of off-premises signs is required, the number of off-premises signs permitted on a street shall be calculated as follows: a. Project the centerline of each off-premises sign structure or sign painted on a structure to the centerline of each street from which the sign face is visible, at right angles to the street. Signs which are set so far back from a street that they are not visible from the street, sign structures which may be visible from the street but are oriented to face another street and permitted business district identification signs, shall not be counted. b. Signs on both sides of the street shall be counted, unless otherwise stated. c. Single-face billboards shall be considered one (1) structure for the purposes of this subsection. d. Double-face or "V" type shall be considered one (1) structure for the purposes of this subsection. e. Visually blocked advertising signs shall be considered one-half (½) of a sign structure for the purposes of this subsection. f. The number of permitted signs shall be measured from the projections made under subsection C1a at the centerline of the street. 2. Where a minimum radial distance between each off-premises sign structure is established, the distance shall be calculated as follows: a. Draw a circle with its center on the centerline of the sign structure, and a radius equal to the minimum required distance (Exhibit 23.86.004 F). b. No off-premises sign except permitted business district identification signs shall be located within the circle. c. Double-face or "V" type billboards shall be considered one (1) structure for the purposes of this subsection. d. When permitted sign area is calculated as a percentage of the area of the face of the structure on which the sign is located, the area of the structure face shall be the elevation of the structure as measured on flat projection from any side, excluding the roof and excluding any chimney, stack, structure, or mechanical equipment on the roof. (Ord. 116780 , § 6, 1993; Ord. 113263, § 42, 1986; Ord. 112830, § 23, 1986; Ord. 112519, § 50, 1985; Ord. 110381, § 1(part), 1982.)

Seattle Mun. Code § 23.86.006 Structure height measurement

A. In all zones except downtown zones, and except for the Living Building Pilot Program authorized by Section 23.40.060 , unless otherwise specified, the height of structures shall be measured according to this subsection 23.86.006.A. 1. General rule. Except as otherwise specified, the height of a structure is the difference between the elevation of the highest point of the structure not excepted from applicable height limits and the average grade level. In this subsection 23.86.006.A, "average grade level" means the average of the elevation of existing lot grades. Except as provided in subsection 23.86.006.A.2, average grade level is calculated, at the discretion of the applicant, as follows: a. at the midpoint, measured horizontally, of each exterior wall of the structure, or b. at the midpoint of each side of the smallest rectangle that can be drawn to enclose the structure. 2. Option for calculating average grade level to measure height. The calculation of structure height in subsection 23.86.006.A.1 may be modified, at the discretion of the applicant, as follows to permit the structure to respond to the topography of the lot: a. Draw the smallest rectangle that encloses the principal structure. b. Divide one side of the rectangle, chosen by the applicant, into sections at least 15 feet in length using lines that are perpendicular to the chosen side of the rectangle. c. The sections delineated in subsection 23.86.006.A.2.b are considered to extend vertically from the ground to the sky. d. The maximum height for each section of the structure is measured from the average grade level for that section of the structure, which is calculated as the average elevation of existing lot grades at the midpoints of the two opposing exterior sides of the rectangle for each section of the structure. B. Within the South Lake Union Regional Center, at the applicant's option, structure height shall be measured either as provided for in subsection 23.86.006.A or 23.86.006.D, or under provisions of this subsection 23.86.006.B. Structure height shall be measured for all portions of the structure. All measurements shall be taken vertically from existing or finished grade, whichever is lower, to the highest point of the structure located directly above each point of measurement. Existing or finished grade shall be established by drawing straight lines between the corresponding elevations at the perimeter of the structure. The straight lines will be existing or finished grade for the purpose of height measurement. When a contour line crosses a facade more than once, that contour line will be disregarded when establishing existing or finished grade. C. Stories or portions of stories of a structure that are underground are not analyzed for purposes of structure height measurement. D. Height measurement techniques in downtown zones and in the South Lake Union Urban Center 1. Determine the major street lot line, which shall be the lot's longest street lot line. When the lot has two or more street lot lines of equal length, the applicant shall choose the major street lot line. 2. Determine the slope of the lot along the entire length of the major street lot line. 3. Measure the maximum height as follows: a. When the slope of the major street lot line is less than or equal to 7.5 percent, the elevation of maximum height shall be determined by adding the maximum permitted height to the existing grade elevation at the midpoint of the major street lot line. On a through-lot, the elevation of maximum height shall apply only to the half of the lot nearest the major street lot line. On the other half of a through-lot, the elevation of maximum height shall be determined by the above method using the street lot line opposite and parallel to the major street lot line as depicted in Exhibit A for 23.86.006 . Exhibit A for 23.86.006 Maximum height Slope Less than or equal to 7-1/2 percent b. When the slope of the major street lot line exceeds 7.5 percent, the major street lot line shall be divided into four or fewer equal segments no longer than 120 feet in length. The elevation of maximum height shall be determined by adding the maximum permitted height to the existing grade elevation at the midpoint of each segment. On a through-lot, the elevation of maximum height shall apply only to the half of the lot nearest the major street lot line. On the other half of a through-lot, the elevation of maximum height shall be determined by the above method using the street lot line opposite and parallel to the major street lot line, as depicted in Exhibit B for 23.86.006 . Exhibit B for 23.86.006 Maximum height Slope greater than 7-1/2 percent c. For lots with more than one street frontage, where there is no street lot line that is essentially parallel to the major street lot line, when a measurement has been made for the portion of the block containing the major street lot line, the next measurement shall be taken from the remaining street lot line that is opposite and most distant from the major street lot line. E. Determining the height of existing public school structures. When the height of the existing public school structure is measured for purposes of determining the permitted height or lot coverage of a public school structure, either of the following measurement methods may be used: 1. If all parts of the new roof are pitched at a rate of not less than 4:12, the ridge of the new roof may extend to the highest point of the existing roof. A shed roof does not qualify for this option; or 2. If all parts of the new roof are not pitched at a rate of not less than 4:12, then the elevation of the new construction may extend to the average height of the existing structure. The average height shall be determined by measuring the area of each portion of the building at each height and averaging those areas, as depicted in Exhibit C for 23.86.006 . Exhibit C for 23.86.006 Maximum elevations for additions to public schools F. Height measurement technique for structures located partially within the Shoreline District. When any portion of the structure falls within the Shoreline District, structure height for the entire structure shall be measured according to Section 23.60A.952 . G. For projects accepted into the Living Building Pilot Program authorized pursuant to Section 23.40.060 , the applicant may choose either the height definition of Chapter 2 of the Seattle Building Code or the height measurement method described in this Section 23.86.006 . (Ord. 127376 , § 92, 2025; Ord. 127375 , § 110, 2025; Ord. 126685 , § 64, 2022 [cross-reference update]; Ord. 126509 , § 93, 2022 [zone name change]; Ord. 125603 , § 80, 2018; Ord. 125272 , § 68, 2017; Ord. 124843 , § 65, 2015; Ord. 124172, § 66, 2013; Ord. 123649, § 64, 2011; Ord. 123564, § 12, 2011; Ord. 123495, § 94, 2011; Ord. 123206, § 7, 2009; Ord. 122823, § 12, 2008; Ord. 122582 , § 3, 2007; Ord. 121476, § 24, 2004; Ord. 121359, § 10, 2003; Ord. 112971, § 1, 1986; Ord. 112539, § 13, 1985; Ord. 112519, § 51, 1985; Ord. 112303, § 24, 1985; Ord. 111926, § 25, 1984; Ord. 110669, § 26, 1982; Ord. 110570, § 21, 1982; Ord. 110381, § 1, 1982.)

Seattle Mun. Code § 23.86.007 Floor area and floor area ratio (FAR) measurement

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)

Seattle Mun. Code § 23.86.008 Lot width in Neighborhood Residential zones

A. When a lot is essentially rectangular, the lot width is the mean horizontal distance between side lot lines measured at right angles to lot depth Exhibit A for 23.86.008 . Exhibit A for 23.86.008 Lot width B. For a lot with more than one rear lot line (Exhibit B for 23.86.008 and Exhibit C for 23.86.008 ), the lot width shall be measured according to the following: Exhibit B for 23.86.008 Lots with more than one rear lot line, and where the distance between the rear lot line is less than 50 percent of lot depth Exhibit C for 23.86.008 Lots with more than one rear lot line, and where the distance between the rear lot line is greater than 50 percent of lot depth 1. If the distance between the rear lot lines is 50 percent or less of the lot depth, the lot width shall be measured parallel to the front lot line and shall be the greatest distance between the side lot lines Exhibit B for 23.86.008 ; or 2. If the distance between the rear lot lines is greater than 50 percent of the lot depth, the lot width shall be determined by measuring average lot width according to Exhibit C for 23.86.008 . C. For irregular lots not meeting the conditions of subsections 23.86.008.A or 23.86.008.B, the Director shall determine the measurement of lot width. (Ord. 127376 , § 94, 2025; Ord. 126509 , § 95, 2022 [zone name change]; Ord. 121476, §§ 25, 26, 2004; Ord. 117263 71, 1994; Ord. 113883, § 4, 1988; Ord. 110669, § 27, 1982; Ord. 110381, § 1, 1982.)

Seattle Mun. Code § 23.86.012 Setback and separations measurement

A. For purposes of setback and separation standards, measurement shall be taken to the outside of building foundations and exterior walls rather than to exterior finishing provided that exterior finishes extend no more than 8 inches into a required setback. B. Setback averaging. In multifamily and commercial zones, certain required setbacks may be averaged. In such cases: 1. The average front and rear setbacks are calculated based on the entire width of the structure; 2. The average side setbacks are calculated based on the entire depth of the structure; 3. Setbacks are measured horizontally from the lot line to the facade of the structure. The facade(s) used in calculating the average and minimum setback requirements shall be those facades that are nearest to that lot line except that any features allowed to project into the setback are excluded. C. Upper-level setback 1. Upper-level setbacks apply only to portions of structures that occur above the height at which the setback begins. 2. For upper-level setbacks required from a street lot line, the height at which the setback begins is measured at all points along the street lot line from sidewalk grade or, if there is no sidewalk, from finished grade at the street lot line. 3. For upper-level setbacks required from other lot lines, the height at which the setback begins is measured at all points along the lot line from the finished grade where the wall meets the grade or, if the structure is cantilevered or posted, where the downward projection of the portion of the structure that is cantilevered or posted meets the grade. (Ord. 127376 , § 96, 2025; Ord. 125791 , § 112, 2019; Ord. 125081 , § 5, 2016; Ord. 124843 , § 67, 2015; Ord. 123495, § 96, 2011; Ord. 115326, § 39, 1990; Ord. 115002 , § 21, 1990; Ord. 114887, § 9, 1989; Ord. 113041, § 22, 1986; Ord. 112971, § 2, 1986; Ord. 111100, § 12, 1983; Ord. 110793, § 72, 1982; Ord. 110570, § 22, 1982.)

Seattle Mun. Code § 23.86.014 Structure width measurement

A. Structure width is measured as follows: 1. Draw the smallest rectangle that encloses the principal structure. 2. Structure width is the length of the side of that rectangle most closely parallel to the front lot line (Exhibit A for 23.86.014 ). Exhibit A for 23.86.014 : Structure Width B. Portions of a structure considered part of the principal structure for the purpose of measuring structure width are as follows: 1. Carports and garages attached to the principal structure, unless they are attached by a structural feature not counted in structure width under subsection 23.86.014.C; 2. Accessory structures, other than carports and garages, that are not listed in subsection 23.86.014.C, if they are less than 3 feet from the principal structure at any point; 3. Exterior corridors, hallways, and open, above-grade walkways; 4. Enclosed porches, decks, balconies and other enclosed projections; and 5. Projecting segments of a facade unless they are not counted in structure width in subsection 23.86.014.C. C. Portions of a structure that are not considered part of the principal structure for the purpose of measuring structure width are as follows: 1. The first 4 feet of cornices, eaves, gutters, roofs, and other forms of weather protection that project from an exterior wall; 2. The first 18 inches of chimneys that project from an exterior wall; 3. Attached solar greenhouses meeting minimum energy standards administered by the Director; 4. The first 4 feet of unenclosed decks, balconies, and porches, unless located on the roof of an attached garage or carport included in structure width in subsection 23.86.014.B.1; 5. Arbors, trellises, and similar features; 6. Detached accessory structures used exclusively for bike parking, even when they are less than 3 feet from the principal structure at any point; and 7. In LR zones, portions of a structure that are exempt from FAR limits pursuant to subsection 23.45.510.D.5. (Ord. 126682 , § 13, 2022; Ord. 125791 , § 113, 2019; Ord. 123495, § 97, 2011; Ord. 118414, § 61, 1996; Ord. 114887, § 10, 1989; Ord. 111390, § 51, 1983; Ord. 110793, § 73, 1982; Ord. 110570, § 23, 1982.)

Seattle Mun. Code § 23.86.015 Maximum facade length measurement

A. In Lowrise zones, the length of certain facades is limited by development standards. Facade length is measured as follows: 1. Draw a line parallel to, and 15 feet from, the lot line along which the length of a facade is limited. 2. For each portion of a structure that is located between the line drawn in subsection 23.86.015.A.1 and the lot line, mark the points at which that portion of the structure crosses the line drawn in subsection 23.86.015.A.1, and measure the distance between those points. 3. The facade length limit applies to the sum of the lengths of the portions of structure(s) measured in subsection 23.86.015.A.2 (see Exhibit A and Exhibit B for 23.86.015 ). Exhibit A for 23.86.015 : Façade Length Exhibit B for 23.86.015 : Façade Length B. Portions of a structure that are included in facade length measurement include: 1. Carports and garages attached to the principal structure, unless they are attached by a structural feature not counted in structure width under subsection 23.86.015.C; 2. Accessory structures, other than carports and garages, that are not listed in subsection 23.86.014.C, if they are less than 3 feet from the principal structure at any point; 3. Exterior corridors, hallways, and open, above-grade walkways; 4. Projecting segments of a facade unless they are not counted in structure width in subsection 23.86.014.C; 5. Enclosed porches, decks, balconies and other enclosed projections; and 6. Projecting segments of a facade unless excluded in subsection 23.86.015.C. C. Portions of a structure that are not included in facade length measurement include: 1. Cornices, eaves, gutters, roofs, and other forms of weather protection; 2. The first 18 inches of chimneys that project from an exterior wall; 3. Attached solar greenhouses meeting minimum energy standards administered by the Director; 4. The first 4 feet of unenclosed decks, balconies, and porches, unless located on the roof of an attached garage or carport included in structure width in subsection 23.86.014.B.1; 5. Arbors, trellises, and similar features; 6. Detached accessory structures used exclusively for bike parking, even when they are less than 3 feet from the principal structure at any point; and 7. In LR zones, portions of a structure that are exempt from FAR limits pursuant to subsection 23.45.510.D.5. (Ord. 126682 , § 14, 2022; Ord. 125791 , § 114, 2019; Ord. 123495, § 98, 2011)

Seattle Mun. Code § 23.86.016 Structure and lot depth measurement

A. Structure depth is measured as follows: 1. Draw the smallest rectangle that encloses a principal structure. 2. Structure depth is the length of the sides of that rectangle most closely parallel to the side lot lines (Exhibit A for 23.86.016 ). Exhibit A for 23.86.016 Structure depth 3. If more than one structure is located on a lot and no portion of a structure is behind any portion of another structure and the structures are separated by a minimum of 10 feet, the maximum depth of each structure shall be measured individually (See Exhibit B for 23.86.016 ). If any portion of a structure is behind any portion of another structure then the structure depth shall be measured as the combined depth of the principal structures on the lot. Exhibit B for 23.86.016 Depth measurement for offset structures B. Portions of a structure considered part of the principal structure for the purpose of measuring structure depth are as follows: 1. Carports and garages attached to the principal structure, unless they are attached by a structural feature not counted in structure depth under subsection 23.86.016.C; 2. Accessory structures, other than carports and garages, that are not listed in subsection 23.86.016.C, if they are less than 3 feet from the principal structure at any point; 3. Exterior corridors, hallways, and open, above-grade walkways; 4. Enclosed porches, decks, balconies, and other enclosed projections; and 5. Projecting segments of a facade unless they are not counted in structure depth in subsection 23.86.016.C. C. Portions of a structure that are not considered part of the principal structure for the purpose of measuring structure depth are as follows: 1. The first 4 feet of eaves, cornices, and gutters that project from an exterior wall; 2. The first 18 inches of chimneys that project from an exterior wall; 3. Attached solar greenhouses meeting minimum energy standards administered by the Director; 4. The first 4 feet of unenclosed decks, balconies, and porches, unless located on the roof of an attached garage or carport included in structure depth in subsection 23.86.014.B.1; 5. Arbors, trellises, and similar features; and 6. In LR3 zones in the Northgate Overlay District, portions of a structure that are exempt from FAR limits pursuant to subsection 23.45.510.D.5. D. Determining lot depth. If development standards are based on lot depth, lot depth is determined as follows: 1. If the lot is essentially rectangular and has a rear lot line within 15 degrees of parallel to the front lot line, the lot depth is the horizontal distance between the midpoints of the front and rear lot lines (Exhibit C for 23.86.016 ). 2. If the lot is triangular or wedge-shaped, lot depth shall be the horizontal distance between the midpoint of the front lot line and the rear point of the lot. If the lot does not actually come to a point, lot depth is measured from midpoint of the front lot line to the midpoint of the rear lot line. 3. In the case of a through lot, lot depth is measured between the midpoint of each front lot line. 4. When lot shape is so irregular that subsections 23.86.016.D.1, 23.86.016.D.2 or 23.86.016.D.3 cannot be used, lot depth is the distance equal to the result of lot area divided by length of front lot line, provided that in no case is the depth permitted to be greater than the distance from front lot line to the furthest point on the perimeter of the lot. Exhibit C for 23.86.016 Measuring Lot Depth (Ord. 125791 , § 115, 2019; Ord. 124843 , § 68, 2015; Ord. 124378 , § 98, 2013; Ord. 123495, § 99, 2011; Ord. 118414, § 62, 1996; Ord. 114887, § 11, 1989; Ord. 113041, § 23, 1986; Ord. 111390, §§ 51, 52, 1983; Ord. 110793, § 74, 1982; Ord. 110570, § 24, 1982.)

Seattle Mun. Code § 23.86.017 Amenity area measurement

If amenity area is required, the following provisions shall apply: A. If the applicable development standards specify a minimum contiguous amenity area, areas smaller than the minimum contiguous area are not to be counted toward fulfilling amenity area requirements. 1. Driveways and vehicular access easements, whether paved or unpaved, shall be considered to separate the amenity areas they bisect. 2. Pedestrian access areas shall not be considered to break the contiguity of amenity area on each side. B. In shoreline areas, when determining the amount of amenity area required or provided, no land waterward of the ordinary high water mark shall be included in the calculation. C. In cases where the shape or configuration of the amenity area is irregular or unusual, the Director shall determine whether amenity area requirements have been met, notwithstanding the following provisions, based on whether the proposed configuration would result in amenity area that is truly usable for normal residential recreational purposes. For the purpose of measuring the minimum horizontal dimension of the amenity area, if one is specified, the following provisions shall apply: 1. For rectangular or square areas, each exterior dimension of the area shall meet the minimum dimension (Exhibit A for 23.86.017 ). Exhibit A for 23.86.017 Measurement of amenity area 2. For circular areas, the diameter of the circle shall meet the minimum dimension. For semicircular areas, the radius of the area shall meet the minimum dimension (Exhibit B for 23.86.017 ). Exhibit B for 23.86.017 Measurement of circular amenity areas (Ord. 127376 , § 97, 2025; Ord. 123495, § 100, 2011)

Seattle Mun. Code § 23.86.018 Open space.

Certain zones require a minimum amount of open space to be provided on the lot. For those cases where open space is required, the following provisions shall apply: A. In order for a portion of a lot to qualify as open space, the ground's surface shall be permeable, except for patios, paved areas designed for recreation, and pedestrian access which meets the Washington State Rules and Regulations for Barrier-Free Design. The area shall be landscaped with grass, ground cover, bushes and/or trees. B. Driveways, parking areas and pedestrian access, except for pedestrian access meeting the Washington State Rules and Regulations for Barrier-Free Design, shall not be counted as open space. C. The area covered or enclosed by solar collectors meeting minimum standards administered by the Director may be counted as required open space. D. Portions of a structure which begin eight (8) feet or more above finished grade may project up to four (4) feet over required ground-level open space. E. Development standards for certain zones specify a minimum contiguous area for open space. Open space areas smaller than the minimum contiguous area specified for such zones shall not be counted toward fulfilling total open space requirements for that lot. 1. Driveways and parking areas, paved or unpaved, shall be considered to separate open space areas they bisect. 2. Pedestrian access areas shall not be considered to break the contiguity of open space on each side. F. In shoreline areas, when determining the amount of open space required or provided, no land waterward of the ordinary high water mark shall be included in the calculation. G. In order for a ground area, roof area, deck or balcony to be considered as open space, it shall have a minimum area and provide a minimum horizontal dimension as established in each zone. In cases where the shape or configuration of the open space is irregular or unusual, the Director shall determine whether open space requirements have been met, notwithstanding the following provisions, based on whether the proposed configuration would result in open space that is truly usable for normal residential open space purposes. For the purpose of measuring the horizontal dimensions of open space, the following provisions shall apply: 1. For rectangular or square areas, each exterior dimension of the area shall meet the minimum dimension (Exhibit 23.86.018 A). 2. For irregularly shaped areas where all lines intersect at or approximately at ninety (90) degree angles, an area which is not less than sixty (60) percent of the minimum dimension in width and does not extend further than sixty (60) percent of the minimum dimension from a contiguous rectangular or square area of which all sides meet or exceed the minimum dimension, may be included as required open space (Exhibit 23.86.018 B). 3. For triangular areas, all exterior dimensions of the area shall meet or exceed the minimum dimensions (Exhibit 23.86.018 C). 4. For circular areas, the diameter of the circle shall meet the minimum dimension; for semicircular areas, the radius of the area shall meet the minimum dimension (Exhibit 23.86.018 D). H. In the case of a lot where a portion is reserved as a vehicular access easement to another lot, when determining the amount of open space required or provided, no land within the limits of the easement shall be included in the calculation except where a portion of the structure is constructed over the easement. (Ord. 120117 § 59, 2000; Ord. 119239, § 43, 1998; Ord. 118414, § 63, 1996; Ord. 114196, § 19, 1988; Ord. 112971, § 3, 1986; Ord. 111390, § 53, 1983; Ord. 110793, § 75, 1982; Ord. 110570, § 25, 1982.)

Seattle Mun. Code § 23.86.019 Green Factor measurement

A. Development standards for certain areas require landscaping that meets a minimum Green Factor score. All required landscaping shall meet standards promulgated by the Director to provide for the long-term health, viability, and coverage of plantings. These standards may include, but are not limited to, the type and size of plants, spacing of plants, depth, and quality of soil, use of drought-tolerant plants, and access to light and air for plants. The Green Factor score shall be calculated as follows: 1. Identify all proposed landscape elements, sorted into the categories presented in Table A for 23.86.019. 2. Multiply the square feet, or equivalent square footage where applicable, of each landscape element by the multiplier provided for that element in Table A for 23.86.019, according to the following provisions: a. If multiple elements listed on Table A for 23.86.019 occupy the same area (for example, groundcover under a tree), count the full square footage or equivalent square footage of each element. b. Landscaping elements in the right-of-way between the lot line and the roadway may be counted, provided that they are approved by the Director of the Department of Transportation. c. Elements listed in Table A for 23.86.019 that are provided to satisfy any other requirements of this Title 23 may be counted. d. For trees, large shrubs, and large perennials, use the equivalent square footage of each tree or shrub according to Table B for 23.86.019. e. For vegetated walls, use the square footage of the portion of the wall covered by vegetation. All vegetated wall structures, including fences counted as vegetated walls, shall be constructed of durable materials, provide adequate planting area for plant health, and provide appropriate surfaces or structures that enable plant coverage. f. For all elements other than trees, large shrubs, large perennials, and vegetated walls, square footage is determined by the area of the portion of a horizontal plane that lies over or under the element. g. All permeable paving and structural soil credits together may not count for more than one third of the lot's Green Factor score. 3. Add together all the products calculated under subsection 23.86.019.A.2 to determine the Green Factor numerator. 4. Divide the Green Factor numerator by the lot area to determine the Green Factor score. Table A for 23.86.019 Green Factor landscape elements Green Factor landscape elements Multiplier A. Planted areas (choose one of the following for each planting area) 1. Planted areas with a soil depth of 24 inches or more: 0.6 2. Bioretention facilities meeting standards of the Stormwater Code, Title 22 , Subtitle VIII 1.0 B. Plants 1. Mulch, ground covers, or other plants normally expected to be less than 2 feet tall at maturity 0.1 2. Medium shrubs or other perennials at least 2 feet tall, but less than 4 feet tall, at maturity 0.3 3. Large shrubs or other perennials at least 4 feet tall at maturity 0.3 4. Small trees 0.3 5. Small/medium trees 0.5 6. Medium/large trees 0.7 7. Large trees 0.9 8. Preservation of existing trees at least 6 inches in diameter at breast height 1.0 C. Green roofs 1. Planted over at least 2 inches but less than 4 inches of growth medium 0.4 2. Planted over at least 4 inches but less than 8 inches of growth medium 0.6 3. Planted over at least 8 inches of growth medium 0.8 D. Vegetated walls in C and NC zones only 0.4 E. Permeable paving 1. Installed over at least 6 inches and less than 24 inches of soil and/or gravel 0.2 2. Installed over at least 24 inches of soil and/or gravel 0.5 F. Structural soil 0.5 G. Bonuses applied to Green Factor landscape elements: 1. Landscaping that consists entirely of drought- tolerant or native plant species 0.1 2. Landscaping that receives at least 50 percent of its irrigation through the use of harvested rainwater 0.2 3. Landscaping visible from adjacent rights-of-way or public open space 0.2 4. Landscaping in food cultivation 0.1 Table B for 23.86.019 Equivalent square footage of trees and large shrubs Landscape elements Equivalent square feet Medium shrubs or other perennials at least 2 feet tall, but less than 4 feet tall, at maturity 9 per plant Large shrubs or other perennials at least 4 feet tall at maturity 36 per plant Small trees 75 per tree Small/medium trees 150 per tree Medium/large trees 250 per tree Large trees 350 per tree Existing trees 20 per inch of trunk diameter 4.5 feet above grade (Ord. 125791 , § 116, 2019; Ord. 123495, § 101, 2011; Ord. No. 123209, § 67, 2009; Ord. 122935, § 24, 2009.)

Seattle Mun. Code § 23.86.023 Street-level facades.

A structure's street-level facade is the portion of the facade that covers the street-level story or stories of a structure along an abutting street. The street-level facade of a structure is measured independently along each abutting street. On flat or sloped streets that span only one story of a structure, the street-level facade is the exterior wall of the story with more than fifty (50) percent of its floor closer to street level than any other story. On sloped streets that span more than one story of a structure, the street-level facade is identified as covering that portion of each story with its floor closer to street level than the floor of any other story. If no floor is closer to street-level than any other floor, the Director shall determine which portion of the facade is the street level. (Exhibit 23.86.023 A). (Ord. 122311 , § 101, 2006.)

Seattle Mun. Code § 23.86.024 Minimum facade height.

A. When a minimum facade height is required in downtown zones, the height of the facade shall be measured from the elevation of the street property line at the sidewalk as depicted in Exhibit 23.86.024 A. Areaways, stairways and other excavations at the property line shall not be considered in measuring the elevation of the street property line. When sidewalk widening is required according to Section 23.49.022 , the height of the facade shall be measured from the elevation of the line establishing the new sidewalk width, rather than the street property line. B. When different minimum facade heights are established at the corner of a lot, the higher minimum height shall continue to be provided around the corner for a distance equal to the higher minimum height required as depicted in Exhibit 23.86.024 B. (Ord. 112519 § 53, 1985; Ord. 111926 § 26(part), 1984.)

Seattle Mun. Code § 23.86.026 Facade transparency

A. In zones, other than Neighborhood Residential or Lowrise zones, where a certain percentage of the street-facing facade is required to be transparent, transparency shall be measured in an area between 2 feet and 8 feet above the elevation of the lot line at the sidewalk, as depicted in Exhibit A for 23.86.026 , unless a different area is specified in the development standards applicable to the lot. Areaways, stairways, and other excavations at the lot line shall not be considered in measuring the elevation of the street lot line. When sidewalk widening is required according to Section 23.49.022 , the elevation of the lines establishing the new sidewalk width shall be used rather than the street lot line. Exhibit A for 23.86.026 Street facade transparency B. When transparency is required for facades that abut bonused public open spaces, the measurement of facade transparency shall be from the elevation of the public open space. C. The full length of Landmark designated structures, and character structures retained according to Section 23.73.015 , shall not be counted in determining the required transparency. (Ord. 127376 , § 98, 2025; Ord. 124503, § 14, 2014; Ord. 123963, § 33, 2012; Ord. 112519 § 54, 1985; Ord. 111926 § 26(part), 1984)

Seattle Mun. Code § 23.86.028 Blank facades

In zones where blank facades are required to be limited, the following provisions shall be used to determine the percent and length of blank facades. A. Percent of blank facades 1. Blank facades shall be measured in an area between 2 feet and 8 feet above the elevation of the lot line at the sidewalk as depicted in Exhibits A and B for 23.86.028 . Areaways, stairways and other excavations at the lot line shall not be considered in measuring the elevation of the street lot line. When sidewalk widening is required according to Section 23.49.022 , the elevation of the line establishing the new sidewalk width shall be used rather than the street lot line. 2. When the blank facade is limited for facades which abut bonused public open spaces, the measurement of facade transparency shall be from the elevation of the public open space. Exhibit A for 23.86.028 Percent of blank facade Exhibit B for 23.86.028 Length of blank facades B. Length of blank facades. The length of a blank facade located within the area established in subsection 23.86.028.A shall be measured between the closest points of adjacent transparent areas, at 5 feet above the elevation of the lot line at the sidewalk, as depicted in Exhibit B for 23.86.028 . C. The following shall not be counted in determining the length of blank facades: 1. Garage doors, as depicted in Exhibit B for 23.86.028 ; and 2. The full length of landmark designated structures, and character structures retained according to Section 23.73.015 . (Ord. 125272 , § 70, 2017; Ord. 124503, § 15, 2014; Ord. 112303 § 26, 1985; Ord. 111926 § 26(part), 1984)

Seattle Mun. Code § 23.86.030 Common recreation area.

Certain zones require that a minimum common recreation area be provided for residential use. When a common recreation area is required, the following provisions shall apply: A. An outdoor area that is not part of a green street or publicly owned open space qualifies as a common recreation area if the ground surface of the area is permeable and is landscaped with grass, ground cover, bushes and/or trees; provided that patios, paved areas designed for recreation, and pedestrian access that meets the Washington State Rules for Barrier-Free Design shall also be considered common recreation area. B. Driveways, parking areas and pedestrian access, except for pedestrian access meeting the Washington State Rules and Regulations for Barrier-Free Design, shall not be counted as common recreation area. C. Development standards in downtown zones specify a minimum contiguous area for common recreation area. Areas smaller than the minimum contiguous area specified shall not be counted toward fulfilling the common recreation area requirements. Driveways and parking areas, paved or unpaved, shall be considered to separate common recreation areas they bisect. Pedestrian access areas shall not be considered to break the contiguity of common recreation areas on each side. D. For an area to be considered a common recreation area, it must have a minimum area and minimum horizontal dimensions as established for downtown zones. For the purpose of measuring the horizontal dimensions of the common recreation area, the following provisions shall apply: 1. In rectangular or square areas, each exterior dimension of the area shall meet the minimum dimension as depicted in Exhibit 23.86.030 A. 2. In irregularly shaped areas in which all lines intersect at or approximately at ninety (90) degree angles, an area which is not less than sixty (60) percent of the minimum dimension in width and does not extend further than sixty (60) percent of the minimum dimension form a contiguous rectangular or square area of which all sides meet or exceed the minimum dimension, may be included as required common recreation area, as depicted in Exhibit 23.86.030 B. 3. In triangular areas, all exterior dimensions of the area shall meet or exceed the minimum dimension as depicted in Exhibit 23.86.030 C. 4. In circular areas, the diameter of the circle shall meet the minimum dimension; for semicircular areas, the radius of the area shall meet the minimum dimension as depicted in Exhibit 23.86.030 D. 5. When the shape of the area is so unusual that the above provisions cannot be applied; for example, when the shape is curvilinear, the Director shall determine when common recreation area requirements have been met. 6. When a portion of a lot is reserved for a vehicular access easement to another lot, no land within the limits of the easement shall be included in the calculation of the common recreation area required, except when a portion of the structure containing common recreation area is constructed over the easement. (Ord. 119728 § 12, 1999; Ord. 111926 § 26(part), 1984.)

Seattle Mun. Code § 23.86.032 Gross floor area in residential, commercial, or other non-residential use

A. When a requirement is based on the percentage of a structure's gross floor area which is in residential use, residential area shall include the following: 1. The gross floor area of all floors or portions of floors of a structure that are devoted entirely to residential use, except as otherwise provided in this Section 23.86.032 ; 2. For required amenity area and open space, accessory parking areas, storage areas, and mechanical rooms are excluded from the calculation of gross floor area in residential use; 3. The prorated portion share of a structure's common areas in the same proportion as the residential use to commercial or other non-residential uses occupying the structure. B. When a requirement is based on the percentage of a structure's gross floor area which is in commercial or other non-residential use, commercial or other non-residential use area shall include the prorated portion share of a structure's common areas in the same proportion as the non-residential or commercial use to residential uses occupying the structure. (Ord. 125603 , § 82, 2018; Ord. 112303, § 27, 1985)

Seattle Mun. Code § 23.86.034 Distance to required parking.

When a maximum distance to required parking is specified it shall be the walking distance measured from the nearest point of the parking area or garage to the nearest point of the lot containing the use the parking is required to serve. (Ord. 112777 § 58, 1986)

Seattle Mun. Code § 23.86.036 Major Institution minimum site and gross floor area measurement.

A. For the purpose of determining whether an institution's site meets the minimum site area to be designated a Major Institution, the following shall be included: 1. All contiguous lots containing Major Institution uses, and lots abutting or across a street or alley and within a radius of two thousand five hundred feet (2,500') of the contiguous lots containing Major Institution uses, including parking lots and outdoor uses and activity areas such as ball courts and playfields primarily used by the Major Institution; 2. If a structure on a lot contains uses other than Major Institution uses, only the area of the lot which contains Major Institution uses or the respective lot area calculated as a percentage of the structure that is occupied by the Major Institution use(s) shall be included. B. For the purposes of determining whether an institution's gross floor area meets the minimum required to be designated a Major Institution, all gross floor area containing Major Institution uses in all structures within a Major Institution's site area, as determined by subsection A of this section, shall be included. (Ord. 115002 , § 22, 1990)
Source: Seattle Municipal Code (Municode library)URL: https://library.municode.com/wa/seattle/codes/municipal_codeFetched: 7/25/2026