Issaquah, WA Fence Regulations: Retaining Walls (2026)
Key Facts
- Permit trigger
- Over four feet in height at any point
- Height measured
- Bottom of the footing to top of the wall
- Maximum wall height
- 10 feet, with trees and shrubs planted in front
- Height in required setback
- Six feet if solely raising the lot grade
- Taller than six feet
- Three-foot guardrail or fence at the top
- Setback for walls over six feet
- One and one-half feet per foot over six feet
Summary
In Issaquah, retaining walls or rockeries over four feet in height at any point need a building permit under IMC Title 16, and Land Use Code § 18.810.100 sets a 10-foot maximum wall height. Inside a required setback the limit is six feet for walls that only raise the grade, and walls over six feet need a three-foot guardrail or fence.
1. Retaining walls or rockeries over four feet in height at any point require a building permit per IMC Title 16 . Height is measured from the bottom of the footing to the top of the wall. 2. Retaining walls must be no taller than 10 feet, with trees (30 to 35 feet on center) and shrubs planted in front of the wall. ... 3. When in a required setback, the following standards apply to retaining walls and rockeries: a. The retaining wall must be limited to six feet in height, when the purpose is solely to raise the grade of the lot; ... c. Rockeries or retaining walls greater than six feet in height must be set back from the property line by one and one-half feet for every one foot over the six-foot height limit. ... 5. Rockeries and retaining walls greater than six feet in height must have a three-foot guardrail or fence at the top.
Full Breakdown
Land Use Code § 18.810.100 is the retaining wall section of the forested hillside chapter. Under 18.810.020, the chapter applies to all development activities that require ground disturbance to slopes 15 percent or greater with a vertical rise of 10 feet or greater; slopes of 15 percent or greater with less than 10 feet of vertical elevation gain are exempt. Within that scope, a retaining wall or rockery over four feet in height at any point needs a building permit under IMC Title 16, and height is measured from the bottom of the footing to the top of the wall. Walls must be no taller than 10 feet, with trees (30 to 35 feet on center) and shrubs planted in front of the wall. If a deviation is approved under 18.810.110, walls must be terraced with enough space between them for shrubs, vines, and groundcover.
Setback rules are tighter. In a required setback, a retaining wall built solely to raise the grade of the lot is limited to six feet. A rockery or wall that protects a cut into an existing grade cannot exceed the greater of the minimum height necessary to support the cut, or six feet. Anything over six feet must be set back from the property line by one and one-half feet for every one foot over the six-foot height limit. A wall created above an existing retaining wall and less than four feet in height must be set back one foot for every one foot in height of the existing wall. Rockeries and walls over six feet need a three-foot guardrail or fence at the top.
Appearance standards follow. Walls of four feet and greater must be articulated under IMC 18.600.090, Fences, walls, and screening, with architectural treatment where they are visible, including downhill portions of the building, plus landscape screening. In single-family subdivisions and plats, walls over four feet tall must be landscaped and terraced where possible, or use decorative wall material or raised planter beds to obscure the surface. Wall height is also tied to the grading rule in 18.810.090(D), which limits cut or fill to not more than 10 feet, and a wall adjacent to a roadway or sidewalk under 18.810.070(C) must be no taller than six feet.
Deviations are requested through the permit process in IMC 18.204.020 and must meet the criteria in IMC 18.202.080; a proposal that fails them needs a variance under Chapter 18.210 IMC.
Violations & Fines
Under IMC 18.108.010, violations of the Land Use Code, including Chapter 18.810, are civil violations enforced under Chapter 8.45 IMC. Under 8.45.120, a notice of violation and order carries a cumulative monetary penalty of $250.00 per day for each violation from the compliance date until compliance, and the violator is also liable for damage to property arising from the violation, including the cost of restoring the affected area.
Frequently Asked Questions
When does a retaining wall need a building permit in Issaquah?
How tall can a retaining wall be in a setback?
Does a tall wall need a fence on top?
Do these wall rules apply to every lot in Issaquah?
Sources & Official References
Other rules in Issaquah
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Retaining Walls in Nearby Cities
How other cities in King County handle retaining walls.