What Seattle’s tree ordinance means for building a house

If there is a tree on your lot with a trunk 24 inches across or more, it will shape the house you can build in Seattle before any design decision does. Under the city’s tree protection code it is a Tier 2 tree, unless it is one of a few excluded species. You can take it down for a new house, a teardown and rebuild, or an addition only on specific grounds, and if it stays, the ground around it is off limits for the whole of construction.

Here is what the code says as of September 2026, including a January 2026 change most summaries online predate, and how I plan around trees from the first sketch.

What the Seattle tree code is now

Seattle’s tree rules are Chapter 25.11 of the Seattle Municipal Code. The current version came from Council Bill 120534, passed as Ordinance 126821, and took effect on July 30, 2023, for projects vested (with a complete permit application) on or after that date.

It has been amended since. According to SDCI, amendments that took effect on January 21, 2026, alongside the city’s new Neighborhood Residential zoning rules, deleted the “basic tree protection area” from the code. SDCI now uses one arborist-defined protection area for two jobs: deciding whether a Tier 2 tree can be removed in Neighborhood Residential and Lowrise zones, and protecting retained trees while you build. Treat every number on this page as correct as of September 2026, and confirm it with SDCI for your project.

The four tiers, and what happened to exceptional trees

Trees are measured at diameter at standard height, or DSH, the trunk diameter 4.5 feet above the ground. Trees under 6 inches DSH are not regulated by the chapter.

Tier	What it covers	No development proposed	With a building permit (Neighborhood Residential zone)
Tier 1	Heritage trees, as defined under the city’s heritage tree program	May not be removed unless hazardous or in need of emergency action	Same. May not be removed unless hazardous or in need of emergency action
Tier 2	Trees 24 inches DSH or more, tree groves and every tree in them, and listed species at smaller sizes	May not be removed unless hazardous or in need of emergency action	Removal only on the grounds in SMC 25.11.070, approved as part of the permit, with replacement
Tier 3	12 inches DSH up to 24 inches, not Tier 1 or Tier 2	Generally may not be removed, with narrow exceptions such as a hazard or proven damage to a foundation	May be removed as part of the development permit, with replacement
Tier 4	6 inches DSH up to 12 inches, not Tier 1 or Tier 2	No more than two in any three-year period on a developed lot	May be removed as part of the development permit

Groves are the Tier 2 trap. A tree grove is eight or more trees of 12 inches DSH or more with a continuous canopy, it can run across property lines, and every tree in it is regulated as Tier 2. Hedges are not groves, and the excluded species below do not count toward one.

Species matter too. Director’s Rule 7-2024 makes some trees Tier 2 well below 24 inches: Pacific madrona, Pacific dogwood, Oregon white oak, Sitka spruce and Pacific yew at 6 inches DSH, and Japanese maple at 12 inches. Some big trees are never Tier 2: red alder, black cottonwood, bitter cherry, Lombardy poplar and trees on the King County noxious weed list. The first four count as Tier 3 from 12 inches.

“Exceptional tree” is the old term. The city says the tiers replaced the exceptional and non-exceptional categories, and the old designation rule, Director’s Rule 16-2008, applies only to projects vested before July 30, 2023. For a project starting today, the question is whether a tree is Tier 2.

When a Tier 2 tree can come out for a house

In Neighborhood Residential zones, which cover Seattle’s single-family lots, SMC 25.11.070 allows a Tier 2 tree to be removed during development only if one of these applies:

• The maximum lot coverage allowed on the site cannot be achieved without extending into the tree’s protection area.
• Avoiding the protection area would leave part of the house, or an accessory dwelling unit, less than 10 feet wide.
• Removal is necessary for new structures, required vehicle or pedestrian access, utilities, retaining walls the city requires, or similar improvements tied to the development.

SDCI runs the lot coverage test on the whole lot. Protection areas are not buildable area, and neither is any strip under 10 feet wide between a protection area and a setback. The city adds up every protection area on the lot, including those of a neighbor’s Tier 1, 2 or 3 trees that fall on your side, and approves removal of only the minimum number of trees needed.

A tree of Tier 2 size is also not regulated as Tier 2 if a registered tree service provider with the ISA Tree Risk Assessment Qualification documents that it is a high risk hazard or unlikely to survive construction, and SDCI agrees. Replacement still applies.

The tree protection area, in feet

The protection area is the ground around a tree where excavation and other construction activity is prohibited unless the city authorizes it in advance. It starts as a circle with a radius of one foot for every inch of DSH. A 30 inch Douglas fir starts with a 30 foot radius, roughly 2,830 square feet of ground (3.14 × 30 × 30 = 2,826).

The project arborist proposes the actual area, adjusted for species, the tree’s size, age and health, soil and the expected construction impacts, and SDCI verifies it. The code limits the reduction:

• New encroachment may not come closer than half the protection radius. For the 30 inch fir, nothing new within 15 feet of the trunk.
• The area may not be reduced by more than 35 percent of the outer half of the radius, unless a certified arborist shows an alternative gives equal or better protection.
• Existing encroachments do not count toward the reduction, and those inside the half radius may remain or be replaced if no appreciable damage results.

How trees shape the buildable footprint

Once the protection areas are drawn, the buildable part of the lot is what is left. If you keep a tree, the code gives some room back. On a Neighborhood Residential lot, to retain an on-site or neighboring tree, the house may extend into the front or rear setback by an area up to the protection area of the trees outside the required setbacks, and required amenity area can shrink by up to the protection area of the trees retained.

That flexibility has a lasting cost. When a permit uses these modifications, the city requires a covenant, recorded with King County, prohibiting development in the protection area for the life of the building or the tree. It limits what a future owner can add.

For a teardown and rebuild, the old house is not a reliable guide. It may stand closer to a tree than a new foundation could, and whether an existing encroachment can be replaced is a question for the arborist and SDCI. If you are still weighing a rebuild against a remodel, this comparison covers the rest of that decision, and the lot coverage and setbacks guide explains the numbers the tree test is measured against.

Additions surprise owners most: a rear addition often lands directly in the protection area of the largest tree on the lot.

What has to be on the permit plans

SMC 25.11.060 and SDCI’s site plan Tip 103 set out what the drawings must show, for a new house, a rebuild or an addition:

• Every Tier 1, 2, 3 and 4 tree on the lot, with location, species and diameter at 4.5 feet, plus off-site trees whose canopy overhangs or whose roots extend onto the lot.
• The protection area of every retained Tier 1, 2 and 3 tree. Tip 103 asks for retained Tier 4 trees as well.
• Tree protection fencing and signage, with SDCI’s Tree and Vegetation Protection Detail in the plan set.
• Any setback or other modification used to avoid a protection area, reviewed and approved by a certified arborist.
• Where replacement is required, a summary table, each replacement tree’s location, species and size, and proposed irrigation, under Director’s Rule 12-2023.

SDCI can also require a tree protection report from a certified arborist to ANSI A300 standards. The Seattle building permit guide covers the wider review.

Replacement trees and payment in lieu

Tier 1, 2 and 3 trees removed for development must be replaced with planting that, once mature, gives canopy cover at least roughly proportional to what was lost. Director’s Rule 12-2023 limits qualifying species to native and/or culturally significant, climate resilient trees, and requires five years of maintenance with 80 percent survival of on-site replacement trees, or 100 percent where only one is planted.

If the lot has no room, you can plant off site, make a voluntary payment in lieu, or combine the two. Director’s Rule 8-2023 sets the amounts, current as of September 2026:

Tree removed	How it is calculated	Amount (Director’s Rule 8-2023)
Tier 1 or Tier 2, 24 inches DSH or more	Per square inch of trunk cross-section at standard height	$17.87 per square inch
Tier 1 or Tier 2 below 24 inches DSH, including grove trees	Per tree, set equal to the amount for a 24 inch tree	$8,080 per tree
Tier 3	Per tree	$2,833 per tree

Using the rule’s own method, a 30 inch Tier 2 tree has a 15 inch radius, so 3.14 × 15 × 15 = 706.5 square inches, and 706.5 × $17.87 is about $12,625. Payment is due to SDCI before the permit authorizing removal is issued. The city reviews these amounts periodically.

Protecting trees during construction

For a tree you keep, the protection area becomes a fenced zone for the whole build. The code’s definition of tree removal includes filling, excavating, grading or trenching in the drip line in a way that can cause irreversible damage. A side sewer trench within the drip line of a Tier 2 tree can count as removing it.

Utility routes, foundation excavation, truck access and storage all have to be planned around the fence. The consequences reach the owner too: the code can treat anyone who directs or pays for damaging work as a responsible party, and SDCI will not issue a development permit on a site while a notice of violation is unresolved.

Anyone you pay to take a tree down must be on SDCI’s tree service provider registry and post a public notice on SDCI’s website at least six full business days before removing any tree of 6 inches DSH or more.

How I design around a tree

The expensive way to meet the tree code is to discover it at permit review, when the agreed footprint turns out to sit inside a protection area. That means redesign after the design fees are spent, on top of a permitting stage that already runs 6 to 10 months for a new house in Seattle, or about 2 to 3 months for a remodel. On a lot with large trees I work in this order:

1. Survey and arborist before any sketch. Every tree of 6 inches DSH and larger located, on the lot and overhanging it, with species, tier, condition and a proposed protection area for each.
2. Map what is left. Protection areas and setbacks drawn together, the remaining buildable area measured, and the Tier 2 lot coverage test checked.
3. Ask SDCI early on a hard lot. Its Land Use Analysis Request has a Tree or ECA Analysis option, where a city arborist gives an opinion on potential removal, protection areas and which trees are best suited to keep.
4. Design with the tree. Footprint, driveway and utility runs outside the protection areas, using the setback flexibility the code allows, treating a retained tree as part of the house, for its shade and privacy.
5. Carry it into construction. Fencing and the protection detail on every sheet that needs them, then checked on site during construction administration.

Sometimes a tree should come out and the code allows it; sometimes the best house is the one built around it. The full sequence, 18 to 30 months from design start to occupancy for a custom home, is in the custom home timeline.

To be clear about my role: Piper Cole designs and administers construction. I do not build houses and I do not remove trees.

Kirkland and Bellevue work differently

The Eastside cities write their own tree rules, and neither uses Seattle’s tiers.

Kirkland

Kirkland’s rules are in Chapter 95 of its zoning code. According to the city’s summary of the amendments effective May 13, 2022, a Tree Retention Plan is required for development needing a building, land surface modification or demolition permit. It gives each regulated tree’s tree protection zone in feet from the trunk.

For single-family homes, Kirkland requires High Retention Value trees to be kept. These include landmark trees, defined as viable regulated trees of at least 26 inches DBH, groves, and viable trees with part of the trunk in a required yard. Before removal is authorized, the applicant must show alternatives were pursued, such as mirroring the footprint or reducing the front yard by up to 5 feet. The city says it will not require retention that reduces maximum floor area ratio or lot coverage, or blocks required access and utilities. Confirm the current chapter with the city. The Kirkland permit guide covers the rest of the process.

Bellevue

Bellevue’s council acted on a comprehensive tree code update on July 9, 2024. A significant tree is now 6 inches in diameter or more and a landmark tree generally 24 inches or more, measured four feet above existing grade, and a permit is required to remove either. Under Land Use Code 20.20.900, new homes and additions or alterations must meet a minimum tree density through retention and new planting, with a strong emphasis on retention, and every development project needs a tree protection plan by a qualified tree professional. The Bellevue permit guide covers the permit side.

Questions

What is the Seattle tree ordinance?

It is Seattle’s tree protection code, Chapter 25.11 of the Seattle Municipal Code. The current version came from Council Bill 120534 (Ordinance 126821) and took effect on July 30, 2023, sorting regulated trees into four tiers by size and type. Amendments effective January 21, 2026 changed how the tree protection area is set, so one arborist-defined area now decides Tier 2 removal and protects retained trees during construction.

Do I need a permit to remove a tree in Seattle?

It depends on whether you are building. With no development proposed, Tier 1, 2 and 3 trees generally may not be removed except for hazards and a few narrow exceptions, and on developed lots in Neighborhood Residential zones only two Tier 4 trees may be removed in any three-year period. When you are building, removal of Tier 2, 3 and 4 trees is decided as part of the development permit, while Tier 1 heritage trees still may not be removed unless hazardous. Anyone paid to remove a tree must be an SDCI registered tree service provider, who posts a public notice on SDCI’s website at least six full business days before removing a tree of 6 inches DSH or more.

What is an exceptional tree in Seattle now?

Exceptional tree is the old term. For projects vested on or after July 30, 2023, Seattle replaced the exceptional and non-exceptional categories with four tiers. The closest match is Tier 2: trees 24 inches DSH or more, trees in groves, and species listed in Director’s Rule 7-2024 at smaller sizes, some as small as 6 inches. The old exceptional tree rule, Director’s Rule 16-2008, applies only to projects vested before that date.

Can I remove a large tree to build a new house in Seattle?

Most trees 24 inches DSH or larger are Tier 2 trees; red alder, black cottonwood, bitter cherry, Lombardy poplar and invasive species are the exceptions. In Neighborhood Residential zones it can be removed during development only if the lot’s maximum lot coverage cannot be achieved without building in its protection area, if avoiding it would leave part of the house or an ADU under 10 feet wide, or if removal is necessary for new structures, required access, utilities or city-required retaining walls. SDCI assesses all protection areas on the lot together and approves only the minimum removal needed. Replacement or a payment in lieu is required.

How big is the tree protection zone during construction in Seattle?

Seattle calls it the tree protection area. It starts as a circle with a radius of one foot for every inch of trunk diameter at 4.5 feet, so a 30 inch tree starts with a 30 foot radius. A project arborist can propose reductions within code limits, including no new encroachment closer than half the radius, and SDCI verifies the result. The retained area must be fenced and signed during construction and shown on the permit plans.

What does Seattle charge instead of replacing a removed tree?

Under Director’s Rule 8-2023, the voluntary payment in lieu of replacement is $17.87 per square inch of trunk cross-section for Tier 1 and Tier 2 trees 24 inches DSH or more, $8,080 per tree for Tier 1 and 2 trees below 24 inches, and $2,833 per Tier 3 tree. A 30 inch Tier 2 tree works out to about $12,625. Payment is due before the permit authorizing removal is issued. Amounts are as of September 2026 and the city reviews them periodically.

Does Seattle’s tree code apply to a home addition?

Yes. The site plans in any building permit plan set must show every Tier 1 to 4 tree on the lot, plus neighboring trees that overhang or root onto it, along with protection areas, fencing and signage for trees being kept. A rear addition often falls inside the protection area of a large tree, so trees should be surveyed before the addition is designed.

What are the tree rules in Kirkland and Bellevue?

Kirkland requires a Tree Retention Plan for development needing a building, land surface modification or demolition permit, and requires single-family projects to retain High Retention Value trees, including landmark trees of 26 inches DBH or more, unless alternatives have been pursued. Bellevue, after its 2024 update, defines significant trees as 6 inches or more and landmark trees as generally 24 inches or more, requires a permit to remove either, and requires new homes and additions to meet a minimum tree density with a tree protection plan.