Seattle Tree Requirements Associated with Development

settle trees and development

Seattle Tree Requirements Associated with Development

Seattle is renowned for its verdant landscapes and lush urban canopy. However, with the city’s growing density and development, preserving these trees requires meticulous attention to detail. The Seattle Department of Construction and Inspections (SDCI) has implemented specific tree protection requirements that developers must follow to protect trees with a diameter of six inches or more. This blog post will delve into these requirements and explain why they are integral to the city’s sustainability efforts.

The Value of Trees in the Urban Landscape

Trees are more than just an aesthetic element in our city. They enhance our environment, improving the quality of our air, and contributing to our health and wellbeing. Recognizing the significance of trees, the SDCI has outlined tree protection requirements in the Seattle Municipal Code (SMC) 25.11 and Director’s Rule 16-2008, Designation for Exceptional Trees.

Tree Protection Requirements: Who and Where Do They Apply?

Tree protection requirements apply to trees with a Diameter at Breast Height (DBH) or Diameter at Standard Height (DSH) of six inches or more. These measurements are taken at 4.5 feet above ground. The requirements apply to properties zoned as neighborhood residential, lowrise, midrise, or commercial, with the qualifying trees on-site.

It’s worth noting that trees located in environmentally critical areas (ECA) are governed by separate regulations under SMC 25.09. For more details, please refer to Tip 331, Environmentally Critical Areas—Tree and Vegetation Overview.

When Can Trees Be Removed?

Under certain circumstances, trees may be removed during development. For example, if a tree prevents the developer from achieving the allowed lot coverage or floor area. However, exceptional trees and those 24 inches DSH or greater require a demonstration that their retention is not feasible.

Tree Protection Areas

In general, tree protection areas are located within the dripline of the tree. The City restricts any development disturbance in these areas, and any reductions must be approved by the Director according to a Tree Protection Report prepared by a registered Tree Service Provider.

Tree Replacement

In all zones, developers must replace each exceptional tree, or any tree 24 inches DSH or greater, with a tree that will provide the same canopy coverage at maturity. This rule also applies to trees authorized for removal in association with development, unless the removed tree qualifies as a hazardous tree.

The Role of Arborist Reports

When proposing a reduction in the tree protection area, developers must submit an arborist report. Prepared by a registered Tree Service Provider, the report details the potential impacts of the proposed development on the tree. The report must contain comprehensive information about the tree, including its health, diameter at standard height, and location, amongst other details.

Plan Set Information

The plan set for the proposed development should include detailed site plan drawings, showing all trees 6 inches DSH or greater on-site or off-site with canopies overhanging and/or roots extending onto the site. They should also clearly indicate the tree protection areas for all trees to be retained.


As Seattle continues to grow and develop, the challenge is to strike a balance between development and maintaining our beautiful urban canopy. By adhering to SDCI’s tree protection requirements, developers play a vital role in preserving Seattle’s natural beauty while shaping its future. For any further inquiries, you can reach out to the SDCI staff via email at or through SDCI’s Submit a Request form.

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