MDK Permitting › Permit guides
Do I need a permit for a retaining wall?
Short walls usually don't. Taller walls, or walls holding something up, usually need a permit and engineered plans.
When does a retaining wall need a permit?
In Oregon, a retaining wall usually needs a building permit when it's more than 4 feet tall, measured from the bottom of the footing to the top of the wall, or when it holds up extra weight above it, like a driveway, a building, or a sloped yard.
When doesn't it?
A wall 4 feet or less, with flat ground and nothing heavy on top, is usually exempt. The city or county still makes the final call.
Does it need an engineer?
Walls that need a permit usually need engineered plans. We draw them, and a licensed Oregon professional engineer stamps them, about $200 at cost.
What do you need from me?
How tall and how long the wall is, what's above it, photos of the slope, and your address.
What it costs
Our price, plus city permit fees worked out from each city’s published fee schedule. City fees are paid to the city and the final amount is set at review. Construction isn’t included.
| Example | MDK price | Washington County | Hillsboro | Portland | Clackamas County | Marion County |
|---|---|---|---|---|---|---|
| 5 ft tall, 40 ft long wall Building permit | $1,100 plans, engineering & permits + engineer stamp about $200 | About $730 | About $185 | About $595 | About $295 | About $215 |
| 8 ft tall, 60 ft long wall Building permit | $1,475 plans, engineering & permits + engineer stamp about $200 | About $1,110 | About $370 | About $935 | About $455 | About $400 |
County columns are for areas outside city limits. Other cities have their own fees. Get your exact numbers with the price builder.
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More permit guides: Decks · Outdoor stairs · Porch & patio covers · ADUs & garage conversions · Additions · Panels, EV chargers & hot tubs · Load-bearing walls · Sheds & fences
General guidance for Oregon homeowners. Rules vary by city and county, and the building official makes the final call. Prices checked against published fee schedules in November 2026.