If you’re a homeowner in Alameda, Albany, Moraga, El Cerrito, Kensington, Oakland, Orinda, Piedmont, and San Leandro, CA.
Why Retaining Walls Fail
Older site retaining walls often start leaning over time. They generally lack wide or deep
footings and the proper drainage for the long term. Moisture in the soil is often the culprit, causing pressure behind the wall, especially when there is an adjacent slope, plants and irrigation.
Properly Engineered Site Retaining Walls
We refer to walls in the yard as site walls. When properly constructed with reinforced
concrete, large footings or piers, and drainage behind them to eliminate potential water
pressure, these new walls will stand the test of time.
Foundation Retaining Walls
When the soil adjacent to a building is higher on one side or the other, the foundations
will function as retaining walls and must be properly designed. If they are over 3’ in
height they need to be engineered. The footings are generally much wider than those of a
standard foundation. When the ground on one side or the other is level, the footing (base)
of the new wall can be place under the adjacent surface, in this case under the driveway
which was then patched over. On the inside of the new wall (which is partially
underneath the building), a French drain is installed adjacent to the building at the base of
the new wall with all the water directed to the street in front.
Retaining Wall with Piers
As an alternative to new walls with wide footings, and a requirement in
hillside scenarios that are sloped on both sides, holes are drilled in which I
beams are set in concrete. For tall walls these holes are often 10’-15’ deep.
Wood Lagging is Installed with I-Beam Walls
Pressure-Treated Wall Boards are installed between the beams- usually 4” thick. Pressure
treated lumber is resistant to termites, dry rot and moisture over time. Because the drop
off is over 30” on the downhill side of the new wall, a 42” minimum height guardrail
system is required above. These railings need to be installed to resist substantial horizonal
forces for safety purposes.
Retaining Wall Drainage
This patio wall is being built with a drainpipe and a drainage mat on the back side. This
mat, called Miradrain directs water to enter it and trickle to the bottom where the pipe is
located, acting like a miniature drainage system. This allows us to form the wall on one-
side only and avoids the need for extensive gravel backfill behind the wall for drainage.
Failing Old Cinder Block Wall
Cinder block walls are often not reinforced, and cinder block is a weak material and is
very porous. Often lacking proper footing and drainage, failure occurs, especially with
taller walls as they age.
Cinder Block Wall Replacement
By install a new reinforced concrete wall with proper footings and drainage this wall can
easily support the much higher soil level in the neighbor’s yard.
Decorative Wall Finishes
Stonework is sometimes installed on new walls to give them a more decorative look.
Stucco Finished New Walls
More commonly, we will install a texture coat of stucco on the new concrete, often to
match the house stucco. This finish is relatively inexpensive and a major upgrade over
Retaining Walls Can Create New Space
By leveling spaces behind or in front of homes and installing new retaining walls level
areas can be created where the spaces were previously unusable. These can be expensive
projects, but for homes with little or no flat areas for recreating or sunbathing this can
make a huge difference.