Retaining Walls: Auburn vs Seattle
How do retaining walls rules compare between Auburn, WA and Seattle, WA?
Auburn has fewer restrictions than Seattle.
Auburn, WA
King County
Retaining walls over 4 feet from footing to top require a building permit and engineering in Auburn under IRC R105.2. Walls near Lea Hill and Lakeland steep slopes face critical area review.
View full Auburn rules →Seattle, WA
King County
King County requires a permit for any retaining wall over 4 ft tall or any wall supporting a surcharge load. Walls in landslide or steep-slope critical areas need geotechnical review regardless of height.
View full Seattle rules →Key Facts Comparison
| Fact | Auburn | Seattle |
|---|---|---|
| Permit Trigger | Over 4 feet | Over 4 ft (footing to top) |
| Engineering | Required over 4 ft | - |
| Critical Areas | Lea Hill, Lakeland steep slopes | KCC 21A.24 review |
| Code | IRC R105.2 / ACC 16.10 | - |
| Surcharge Rule | - | Permit at any height |
| Geotech | - | Required in slope hazards |
| Drainage | - | Required by IRC |
Highlighted rows indicate differences between cities.
Auburn FAQ
Do I need a permit for a 3 foot retaining wall in Auburn?
Generally no, unless it supports a surcharge or sits in a critical area. Walls 4 feet or less that do not support fill above are permit-exempt under IRC R105.2.
Is engineering required for retaining walls in Auburn?
Yes, for any wall over 4 feet and for walls in steep-slope critical areas, engineered design stamped by a licensed Washington engineer is required.
Seattle FAQ
How tall can my retaining wall be without a permit in unincorporated King County?
Up to 4 feet from the bottom of the footing to the top of the wall, with no surcharge load. Walls in a mapped landslide or steep-slope hazard area typically need a permit and geotechnical report regardless of height.
Do I need an engineer for my retaining wall?
Yes if the wall is over 4 feet, supports a surcharge, or is located in a landslide, steep-slope, or erosion hazard area. A licensed geotechnical or civil engineer must prepare the report.
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