Do I need a permit to remove a tree for my Seattle addition?
Answered by AskBaily Editorial · Updated
Short answer
Probably. SMC Title 25.11 — Seattle's Tree Protection Ordinance — regulates exceptional trees (species-specific thresholds, typically 24 inches DBH or greater) and trees within required critical-areas buffers. Removal or substantial impact inside a tree's drip line during construction requires SDCI tree-protection review and, for exceptional trees, a permit with replacement or in-lieu-fee obligations.
In detail
In most cases involving a meaningful Seattle addition, yes — tree work falls inside the scope of Seattle Municipal Code Title 25.11 and almost always triggers some form of SDCI tree-protection review before a permit issues. The ordinance regulates trees by size, species, and location, with the toughest controls reserved for so-called Tier 2 (formerly exceptional) trees. Tier 2 thresholds are species-specific, but most large stems at 24 inches diameter at breast height (DBH) or greater qualify, and certain sensitive species (Pacific madrone, Pacific yew, oak, Garry oak, Western red cedar) cross into protected status at smaller diameters.
When a tree sits inside an Environmentally Critical Area buffer (steep slopes, riparian corridors, wetlands), it is regulated under SMC 25.09 in addition to 25.11, and removal generally cannot proceed without an approved critical-areas review. Even healthy non-Tier-2 trees over 6 inches DBH are now counted toward your lot tree credit and must be inventoried on plans submitted with your Master Use Permit.
For a typical residential addition, expect to file a Tree Protection Plan stamped by an ISA-certified arborist, identify all regulated trees within the zone of construction influence, and either preserve them with fenced root zones outside the drip line or apply for a removal permit. Tier 2 removals usually require replacement plantings under SMC 25.11.090 or payment into the in-lieu-fee fund.
Grading, foundation excavation, or trenching for utilities inside the drip line of any regulated tree is treated as substantial impact and requires the same arborist review as outright removal. Pretending a tree is unaffected because the trunk is outside the building footprint is a common reason permits stall.
Budget two to four weeks for SDCI tree review on top of structural plan check, and assume any Tier 2 specimen will add cost in either replacement stock or fee-in-lieu (currently calculated by the City Forester using replacement-cost methodology).
Sources
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