The short answer
Retaining walls in Redwood City cover three kinds of ground: soft bay fill at Redwood Shores, flat older neighborhoods in the middle and steep, slide-prone hills in Emerald Hills and Palomar Park. San Fran Retaining Wall Pros builds walls for each, with footings and drainage matched to what's underneath.
Three kinds of ground in one city
Redwood City runs from the bay to the ridge. Redwood Shores, on the east, is built on filled bay margin. The middle, around downtown, Roosevelt, Mount Carmel and Woodside Plaza, is flat alluvial ground. West of Interstate 280, Emerald Hills, Palomar Park and Edgewood bring real slopes.
A short wall in the Shores needs a wide footing on soft soil. A tall wall in Emerald Hills needs depth, steel and a slope that isn't moving.
Redwood Shores and soft ground
Redwood Shores sits on engineered fill over soft bay mud. The water table is shallow and the ground can settle over time, and it can liquefy in a major earthquake. Walls here are low: planters, patio edges, boat-dock and lagoon-edge walls.
- Wide, reinforced footings to spread load
- Compacted aggregate base under every wall
- Drainage and waterproofing, since groundwater is close
- Corrosion-resistant materials near the lagoon and bay
- Care with utilities, since many lines run close to the surface
Lagoon and shoreline edges often call for boulder or engineered concrete, with permits that can involve regional agencies.
Emerald Hills, Palomar Park and the slide problem
The hills above Redwood City are made of Franciscan rock and weathered soil, with serpentinite in places. Many slopes have a history of movement in wet winters, and some streets have been repaired after slides.
- Drilled pier and soldier pile walls for cut slopes
- Interceptor drains uphill of the wall to catch runoff
- Deep footings set on firm material, not on creeping soil
- Erosion control while a cut is open
- Geotechnical review before any tall wall is designed
See our hillside retaining wall page. On slopes like these, the soils report comes first.
Faults, creeks and rules
The San Andreas Fault runs through the hills just west of the city, so engineered walls are designed for strong shaking. Redwood Creek, Cordilleras Creek and others cross town, and work near them can involve setbacks and permits. Redwood City also protects many trees.
| Situation | What applies |
|---|---|
| Wall over 4 ft from footing to top | Permit and engineering |
| Hillside or slide-prone lot | Geotechnical review |
| Near a creek or lagoon | Setbacks and agency review |
| Heritage tree nearby | Tree protection rules |
| Wall with a driveway above | Surcharge design |
Redwood City neighborhoods and their walls
- Redwood Shores. Low walls, soft ground, lagoon edges.
- Downtown, Roosevelt and Mount Carmel. Older homes with brick and concrete walls and root problems.
- Woodside Plaza and Farm Hill. Gentle slopes with terraces and driveway walls.
- Emerald Hills. Steep lots, tall cuts, views and slide history.
- Palomar Park and Edgewood. Canyon terrain, serpentine ground and habitat rules.
What we check on a Redwood City visit
- Whether the ground is fill, alluvium or hillside rock and soil
- Water at the base of the wall in dry weather
- Cracks or offsets in the slab and wall that suggest slope movement
- Where street and roof runoff goes
- Heritage trees and creek setbacks
- Access for pumps, machines and hand crews
A typical Redwood City job
An Emerald Hills home has a tall block wall behind the garage. It's leaning, with water seeping out at the base, and the slope above has bare, eroding soil.
We recommend a drilled-pier or deep-footed concrete wall, an interceptor drain above and a pipe behind with a clear outlet. The old wall comes out in sections, and the slope above gets erosion control and deep-rooted planting.
Redwood City retaining wall FAQ
Do walls at Redwood Shores need special footings?
Yes. Soft fill and shallow groundwater call for wide, reinforced footings, a compacted base and good drainage.
Is Emerald Hills prone to landslides?
Parts of the hills have a history of slope movement in wet winters. A geotechnical report is the first step for tall walls there.
Do I need a permit in Redwood City?
Generally for walls over four feet from the bottom of the footing to the top or with a surcharge. Hillside, tree and creek rules can add steps.
What's best at the lagoon edge?
Boulder or engineered concrete walls, built with corrosion-resistant materials. Permits may involve regional agencies.
Can you fix a leaning wall without replacing it?
Sometimes. If it's straight enough and the drainage can be fixed, repair may work. Walls that are leaning or cracked horizontally usually need more.
Retaining wall services in Redwood City
Every service below is available in Redwood City. Pick the one that matches your wall.
- Retaining Wall Installation
- Retaining Wall Repair
- Retaining Wall Replacement
- Concrete Retaining Walls
- Cinder Block Retaining Walls
- Wood Retaining Walls
- Stone Retaining Walls
- Boulder Retaining Walls
- Interlocking Block Retaining Walls
- Gabion Retaining Walls
- Retaining Wall Drainage
- Hillside Retaining Walls
Nearby: San Mateo, Palo Alto, Burlingame. Or see every city we work in.