Seattle Rockeries
Retaining Wall Contractor in Redmond, WA
Redmond splits between valley and upland, and a wall has to be built for the one it is on.
The valley floor along the Sammamish River, Bear Creek, and Evans Creek sits on soft alluvial and organic soils with a high water table, and the city maps much of it as seismic hazard where the ground can liquefy in a quake.
The uplands in Education Hill, Union Hill, and Grass Lawn are glacial till cut by steep creek ravines that carry erosion and landslide risk. Redmond's own code prefers retaining walls that hold a natural slope in place over regrading it, which is exactly how we work.
Seattle Rockeries builds rockery, block, and gabion walls across Redmond, and on both kinds of ground the water and the slope are the real problem, not the wall face.
Redmond Soil and Terrain
Redmond's uplands sit on dense glacial till with looser sand and gravel above it. Water drains through the upper soil, hits the till, and runs sideways, which loads walls and drives erosion on the ravine slopes along Bear Creek and Evans Creek.
The valley floor is different ground entirely. It is soft river alluvium and organic soil with a high water table, and the city maps it as seismic hazard because saturated loose soil can liquefy and lose strength in an earthquake.
A wall in the valley is a foundation and drainage problem first. A wall on the slopes is a slope stability and drainage problem. Either way the water comes first.
On the upland slopes we build slope stabilization and tiered walls sized for soil and water load. On the valley floor we build drainage walls and set footings for soft, wet ground.
What We Build in Redmond
On Redmond's valley and upland lots, from the Sammamish River and Bear Creek valley floor to Education Hill, Union Hill, and Grass Lawn, we build:
Recent Redmond Project
On a Redmond property, we excavated and built a tiered block retaining wall with steps and reworked the grade around the yard.
“Highly recommend Seattle Rockeries. Harry, Ben, and crew were masterful and professional start to finish. Our vision and cost was aligned up front, and project quality was delivered beyond expectations. Good team effort.”
JJ Ost, Redmond. Five-star Google review.
How Much Does a Retaining Wall Cost in Redmond?
What a wall costs in Redmond comes down to height, length, material, access, and how much the ground demands. In the valley the cost can include a liquefaction evaluation and deeper footings for soft ground, while upland ravine lots add slope work.
| Project Type | Typical Cost Range | Common Scope |
|---|---|---|
| Low garden or landscape wall | $4,000 to $12,000 | Small retaining walls for landscape support, grade transitions, or garden areas. |
| Mid-size structural wall | $12,000 to $35,000 | Two- to four-foot walls with drainage built in. |
| Engineered hillside wall | $35,000 to $90,000 and higher | Walls over four feet, tiered systems, engineered designs, permitting, and hillside work. |
| Education Hill or Union Hill slope project | Premium | Tiered engineered walls on upland slopes with drainage, difficult access, slope stabilization, and permitting requirements. |
We give a written estimate after seeing the site.
Redmond Permit and Code FAQ
Do I need a permit for a retaining wall in Redmond?
Yes for any wall over four feet tall, measured from the bottom of the footing to the top of the wall, not just the part you can see. Yes for a wall of any height that supports a surcharge. Walls over four feet also require an engineered design with calculations.
What counts as a surcharge load?
Any load above or behind the wall, such as a slope, a driveway, a parking pad, or a structure. A wall supporting a surcharge needs a permit at any height, even under four feet.
Do two short walls stacked close together get around the permit?
No. If the upper wall is not set back far enough, about twice the height of the lower wall, it loads the lower wall as a surcharge, and a wall supporting a surcharge needs a permit at any height.
What if my lot is in a hazard area?
Under RZC 21.64, a lot mapped as landslide, erosion, or seismic hazard requires a geotechnical study, and on seismic ground in the Sammamish River and Bear Creek valleys that includes a liquefaction evaluation.
Does Redmond limit how I can build on a slope?
Yes. In landslide hazard areas development is largely prohibited, and where building is allowed the code wants foundations tiered to the existing slope and the natural contour kept, rather than cut and regraded. That is how we build on slopes anyway.
Permit information is based on Redmond Zoning Code Chapter 21.64, Critical Areas, Geologically Hazardous Areas, current as of June 2026. We confirm the requirements for your specific lot as part of the quoting process and handle the permit submittal on permitted projects.
Drainage and Why Walls Fail
Most retaining walls in Redmond do not fail because the wall was weak. They fail because water built up behind them. In the valley the water table sits high year round, and on the upland ravine slopes water perches on the till and pushes sideways against the back of the wall.
A wall without a real drainage system, meaning perforated pipe, gravel backfill, and a working outlet, builds hydrostatic pressure and starts to lean, bulge, or crack. When we are called to repair a failed Redmond wall, the cause is almost always drainage or a footing set too shallow.
Every wall we build drains from the start, and when we rebuild behind an existing wall, we fix the drainage first.
Get a Redmond Retaining Wall Quote
If your Redmond property needs a new retaining wall, rockery, block wall, gabion wall, drainage rebuild, or repair, Seattle Rockeries can review the site and provide a written estimate.