Retaining wall cost in Seattle (2026):
prices by material and height, and when you need a permit
HOW MUCH DOES A RETAINING WALL COST IN SEATTLE?
HomeAdvisor puts a retaining wall in Seattle at $3,951 to $11,147, with an average of $7,477. HomeGuide's national figures are $20 to $50 per square foot of wall, or $4,000 to $10,000 for a wall 50 feet long and 4 feet tall. In Seattle, a wall over 4 feet, measured from the bottom of the footing, needs a construction permit, and so does any wall on a parcel with an environmentally critical area.
Retaining wall cost in Seattle
| Seattle (HomeAdvisor) | Reported cost |
|---|---|
| Typical range | $3,951–$11,147 |
| Average | $7,477 |
| Low end / high end | $2,500 / $15,000 |
Cost by material
| Material | Per square foot of wall, installed |
|---|---|
| Timber | $10–$40 |
| Gabion (wire baskets of stone) | $10–$40 |
| Natural stone | $10–$85 |
| Block | $15–$55 |
| Poured concrete | $20–$45 |
| Boulder (rockery) | $25–$50 |
| Brick | $30–$60 |
Cost by length and height
| Length | 2 ft tall | 4 ft tall | 6 ft tall |
|---|---|---|---|
| 10 ft | $400–$1,000 | $800–$2,000 | $1,200–$3,000 |
| 50 ft | $2,000–$5,000 | $4,000–$10,000 | $6,000–$15,000 |
| 100 ft | $4,000–$10,000 | $8,000–$20,000 | $12,000–$30,000 |
Extra costs to plan for
| Item | Reported cost |
|---|---|
| Drainage behind the wall | $10–$30 per linear foot |
| Engineer or landscape architect design | $100–$220 per hour |
| Permit (national average) | $50–$450 |
| Removing an old wall | $10–$20 per sq ft |
| Excavation and disposal | $125–$225 per cubic yard |
Washington sales tax applies to the whole contract, labor included. In Seattle the rate is 10.55% (Washington Department of Revenue, October–December 2026), so a $7,477 wall comes to about $8,266 with tax (our calculation). Rates for other cities: sales tax on home repairs.
When you need a permit in Seattle
| Wall | SDCI permit |
|---|---|
| 4 ft or lower (from the bottom of the footing), no ECA, can't damage neighbors | No construction permit |
| Over 4 ft, or could damage an adjoining property (for example, at the property line) | Construction permit |
| Any height on a parcel with an environmentally critical area (ECA) | Not allowed unless you meet specific requirements or get an exemption |
| A lot of soil moved or area disturbed | Grading permit may be required |
- Rockeries: SDCI requires a geotechnical engineer's design, or the prescriptive standards in SDCI Tip 321.
- Drains: if the drain behind the wall connects to a side sewer, you need a side sewer permit.
- Location: the wall must be on your property. Building in the public right-of-way brings additional requirements.
- Lot coverage: retaining walls and rockeries don't count toward lot coverage.
- Fences on top: a fence on a retaining wall that raises the grade is limited to 9 feet 6 inches combined. See fence cost in Seattle.
Outside Seattle, cities in King County have their own rules. Ask your city's permit center before you build.
Before you sign
- Get the wall's height from the bottom of the footing in writing; that's the number that decides the permit.
- Ask how the wall will drain, and whether drainage is in the price.
- Ask who prepares the drawings and applies for any permit.
- Check the contractor on L&I's Verify a Contractor tool, and keep the first payment small: see contractor down payments.
Frequently asked questions
How much does a retaining wall cost in Seattle?
HomeAdvisor puts a retaining wall in Seattle at $3,951 to $11,147, with an average of $7,477. HomeGuide's national figures are $20 to $50 per square foot of wall face.
Do I need a permit for a retaining wall in Seattle?
Yes, if the wall is over 4 feet tall measured from the bottom of the footing, if it could damage an adjoining property, or if the parcel has an environmentally critical area. A grading permit may also be needed.
How is retaining wall height measured in Seattle?
From the bottom of the footing to the top of the wall, even if the footing is below the ground, according to SDCI.
What is the cheapest retaining wall material?
In HomeGuide's figures, timber and gabion walls start at about $10 per square foot, while brick runs $30 to $60. Natural stone has the widest range, $10 to $85.
How much does a 4-foot retaining wall cost?
HomeGuide lists $80 to $200 per linear foot for a 4-foot wall, or $4,000 to $10,000 for 50 feet. Drainage, removal of an old wall and sales tax are extra.
Other outdoor work: exterior and yard cost guides.
About these prices. The ranges are published estimates from the sources below, as of the dates shown. Material costs, labor rates, tariffs and inflation can change prices after those dates, and your home may differ. Use them to plan a budget, then get written quotes from licensed contractors.
Sources
- Seattle Department of Construction and Inspections — Retaining walls and rockeries
- HomeAdvisor — Retaining wall contractors in Seattle, WA
- HomeGuide — How much does a retaining wall cost?
- Washington Department of Revenue — Custom construction
All sources accessed November 10, 2026.
This guide summarizes published cost estimates and City of Seattle rules. Confirm permit requirements with SDCI (206-684-8600) before work starts, and get written quotes from licensed, bonded contractors. See our disclosure and disclaimer.