Tree requirements
Seattle Mun. Code § 23.44.120
in effectA. Development containing one or more new dwelling units must plant or retain trees to either achieve the number of tree points listed in Table A for 23.44.120 or provide at least one new tree for every 2,500 square feet of lot area, whichever results in the greater number of trees. Table A for 23.44.120 Number of tree points required Density (dwelling units per lot size) Tree points required per lot area 1 Less dense than 1 unit/4,000 square feet 1 point/500 square feet 1 unit/4,000 square feet to 1 unit/2,201 square feet 1 point/600 square feet 1 unit/2,200 square feet to 1 unit/1,601 square feet 1 point/675 square feet 1 unit/1,600 square feet or denser 1 point/750 square feet Footnote to Table A for 23.44.120 1 For purposes of this Section 23.44.120 , lot area shall not include submerged lands. B. Individual trees preserved during construction or planted as part of construction, excluding street trees, count toward the tree score according to Table B for 23.44.120. Trees required under Section 25.11.090 shall count toward this standard. All required trees shall meet standards promulgated by the Director to provide for the long-term health and viability of plantings. These standards may include but are not limited to tree selection, invasive species, planting specification, soil and mulch amendment, and protection practices during construction. Table B for 23.44.120 Tree points Type of tree Tree species Points for deciduous trees Points for evergreen trees Trees planted as part of construction Small 1 point 1.25 point Small/medium 2 points 2.5 points Medium/large 3 points 3.75 points Large 4 points 5 points Trees preserved during construction Small 0.4 point per inch of diameter 0.5 point per inch of diameter Small/medium 0.8 point per inch of diameter 1 point per inch of diameter Medium/large 1.2 point per inch of diameter 1.4 point per inch of diameter Large 1.6 point per inch of diameter 1.8 point per inch of diameter C. Tree protection areas shall be designated in accordance with Section 25.11.060 for all trees that are proposed to be preserved to receive points under subsection 23.44.120.B, regardless of tree tier. D. The owner of the subject lot is required to ensure that the trees planted remain healthy for at least five years after inspection by the City, and the owner of the subject lot shall be responsible for replacing any trees that do not remain healthy after inspection by the City. E. Tree measurements 1. New trees planted to meet this requirement shall meet the following size standards: a. Deciduous trees with one trunk must be at least 1.5 inches in diameter, measured 6 inches above the ground. b. Multi-stemmed deciduous trees must have at least three stems and be at least 6 feet tall. c. Evergreen trees must be at least 4 feet tall. 2. Existing trees shall be measured 4.5 feet above the ground. F. Tree location. New trees planted to meet this requirement shall not be planted: 1. For small species trees, within 2 feet of a dwelling unit; 2. For small/medium species trees, within 4 feet of a dwelling unit; 3. For medium/large species trees, within 6 feet of a dwelling unit; 4. For large species trees, within 8 feet of a dwelling unit; and 5. For all trees, within 2 feet of a sidewalk located in the right-of-way. G. Street tree requirements 1. Street trees are required for development that would add one or more principal dwelling units on a lot, except as provided in subsection 23.44.120.G.2 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. If it is not feasible to plant street trees in a right-of-way planting strip, a 5-foot setback shall be planted with trees along the street lot line that abuts the required front setback, 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 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. 127376 , § 31, 2025.)
Source: Seattle Municipal Code (Municode library)URL: https://library.municode.com/wa/seattle/codes/municipal_codeFetched: 7/25/2026