Retaining Wall Contractors in South San Francisco, CA

The short answer

Retaining walls in South San Francisco mostly mean steep residential lots on the slopes of Sign Hill and San Bruno Mountain, with stair-step streets and homes cut into the hillside. San Fran Retaining Wall Pros builds reinforced block, concrete and hillside walls here, with drainage planned for fast runoff and ground that's often rocky or fractured.

A city built on the slopes

South San Francisco is a city of two halves. The flat east side near the bay is industrial and commercial. West of El Camino, the ground tilts up toward Sign Hill and San Bruno Mountain, and the neighborhoods of Sunshine Gardens, Westborough, Avalon, Winston Manor and Paradise Valley are all built on slopes.

Streets climb in short, steep blocks, and houses stack up the hillside. Many have garages at street level and living space above, with a back yard cut into rock or soil behind. The walls that make those lots usable are everywhere, and many are older than the people who live behind them.

Rock, fill and fractured ground

San Bruno Mountain and Sign Hill are made mostly of Franciscan rock, a mixed bag of greywacke sandstone, chert, shale and serpentinite. Where the rock is close to the surface, it's strong and good for footings. Where it's weathered or fractured, it breaks into chunks and clay. Many lots were built by cutting into the hill and pushing the cut material downhill as fill.

Shallow bedrock. Great for bearing, harder to excavate, sometimes requires a breaker or a drill
Fill benches. Need deeper footings or piers to reach firm ground
Fractured rock. Can shed loose material onto walls and yards
Seeps and springs. Common where water travels along rock layers, needing good drains

A drilled pier, soldier pile or deep-footed concrete wall makes sense on many of these slopes. See our hillside wall page for details.

Wind, fog and fast runoff

The gap between San Bruno Mountain and the hills to the south funnels wind through South San Francisco. Fog and wind are part of the weather, and when rain comes it runs off steep slopes fast. Concentrated water above a wall is one of the most common causes of damage we see.

A good wall setup here includes surface drains, a catch basin or swale above the wall and downspouts piped away from the slope. Our drainage work is built into every wall we do.

Mountain habitat, permits and city rules

San Bruno Mountain is a protected habitat area with rare plants and butterflies. Properties right at the mountain's edge may have restrictions on grading and planting. Elsewhere, standard rules apply, with permits for walls over four feet and for walls with a surcharge.

Hill lots also tend to have shared fence lines, stairs and utility easements. We take a careful look at where the property line sits before we design anything that might cross it.

What we're usually asked to build

A tall concrete wall behind a garage to hold up a back yard
A replacement for a failed timber wall along a hillside driveway
A reinforced block wall to create a flat patio on a slope
A drainage fix for water pushing through a wall
Terraced planting walls on a steep front yard
A boulder or gabion wall along a drainage swale

On lots with tight access, we use hand-carried block, hose-fed concrete and small tracked machines.

South San Francisco neighborhoods and their walls

Sign Hill and Old Town. Steep, older lots, with stone and concrete walls along stair-step streets.
Sunshine Gardens and Avalon. Hillside homes with garages tucked below and back yards cut into rock and soil.
Westborough. Mid-century neighborhoods on rolling slopes, with block walls that are reaching the end of their life.
Winston Manor and Paradise Valley. Lots near the base of the slope where runoff collects.
Near San Bruno Mountain. Steeper ground, habitat rules and fast runoff.

What we look for on a South San Francisco visit

How close bedrock is to the surface, and whether the wall is bearing on it
Where runoff from the street and the slope above is going
Seeps and springs, especially after rain
Fill benches that may have settled
Cracks in garage slabs or retaining walls near stairs
Whether a big machine fits, or whether a hand crew is the only option

A typical South San Francisco job

A hillside home has a failing block wall behind the garage. The wall is about six feet tall, with horizontal cracks and efflorescence. Water seeps from the slope above.

We recommend a replacement in reinforced concrete with a deep footing set on firm material, plus an interceptor drain above the wall and a perforated pipe behind it. The excavation is done in sections so the slope stays supported, and the new wall is faced to match the house.

South San Francisco retaining wall FAQ

What causes retaining walls to fail in South San Francisco?

Mostly water and weak backfill. Steep slopes shed runoff fast, and older walls often lack drainage or steel. Fill that wasn't compacted can also settle and push on walls.

Can you build a wall in rock?

Yes. Shallow rock can be an excellent base, but it takes the right equipment to excavate. We plan for it, and use anchors or piers when it helps.

Do walls near San Bruno Mountain have special rules?

Properties at the mountain's edge may face habitat and grading restrictions. We check before work starts.

How do you work on steep, narrow streets?

We plan deliveries, use pumps and hand crews, and coordinate with neighbors when work affects parking or access.

What wall is best for a steep South San Francisco back yard?

Reinforced concrete or block is the usual answer for tall walls. Piers or tiebacks are used when the slope is unstable.

Retaining wall services in South San Francisco

Every service below is available in South San Francisco. Pick the one that matches your wall.

Nearby: San Bruno, Brisbane, Daly City. Or see every city we work in.