23.45.524

A. Landscaping requirements 1. Standards. All landscaping provided to meet requirements under this Section 23.45.524 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, number of plants, spacing of plants, depth and quality of soil, use of drought-tolerant plants, and access to light and air for plants. 2. Green Factor requirement a. Landscaping that achieves a Green Factor score of 0.6 or greater, determined as set forth in Section 23.86.019 , is required for any lot within an LR zone if construction of more than one new dwelling unit or a congregate residence is proposed on the site. The addition of any new dwelling unit that does not increase the floor area on the site is exempt from the Green Factor requirement. b. Landscaping that achieves a Green Factor score of 0.5 or greater, determined as set forth in Section 23.86.019 , is required for any lot within an MR or HR zone if construction of more than one new dwelling unit or a congregate residence is proposed on the site. The addition of any new dwelling unit that does not increase the floor area on the site is exempt from the Green Factor requirement. B. Street tree requirements. 1. Street trees are required if any type of development is proposed, except as provided in subsection 23.45.524.B.2 and B.3 below and Section 23.53.015 . Existing street trees shall be retained unless the Director of the Seattle Department of Transportation approves their removal. The Director, in consultation with the Director of the Seattle Department of Transportation, shall determine the number, type, and placement of additional street trees to be provided in order to: a. improve public safety; b. promote compatibility with existing street trees; c. match trees to the available space in the planting strip; d. maintain and expand the urban forest canopy; e. encourage healthy growth through appropriate spacing; f. protect utilities; and g. allow access to the street, buildings and lot. 2. Exceptions to street tree requirements. a. If a lot borders an unopened right-of-way, the Director may reduce or waive the street tree requirement along that right-of-way as a Type I decision if, after consultation with the Director of the Seattle Department of Transportation, the Director determines that the right-of-way is unlikely to be opened or improved. b. Street trees are not required for any of the following: 1) changing a use 2) expanding a structure by 1,000 square feet or less; 3) expanding surface parking by less than 10 percent in area and less than 10 percent in number of spaces; or 4) establishing a temporary or intermittent use pursuant to Section 23.42.040 . c. If an existing structure is proposed to be expanded by more than 1,000 square feet, one street tree is required for each 500 square feet over the first 1,000 square feet of additional structure, up to the maximum number of trees that would be required for new construction. 3. If it is not feasible to plant street trees in a right-of-way planting strip, a 5 foot setback shall be planted with street trees along the street lot line, or landscaping other than trees shall be provided in the planting strip, subject to approval by the Director of the Seattle Department of Transportation. If, according to the Director of the Department of Transportation, a 5 foot setback or landscaped planting strip is not feasible, the Director may reduce or waive this requirement as a Type I decision. (Ord. 126685 , § 23, 2022; Ord. 125272 , § 20, 2017; Ord. 124608 , § 7, 2014; Ord. 123495, § 35, 2011; Ord. No. 123209, § 38, 20090