If you’re a homeowner in Alameda, Albany, Moraga, El Cerrito, Kensington, Oakland, Orinda, Piedmont, and San Leandro, CA.
Shoring, Cribbing and I-Beam supports
The first step in the digout project is to support the building in place so the foundations
can be removed and digging can occur. It can be done with large steel beams that support
the entire length of the building, or smaller beams to support portions of the house. We
prefer to do our own shoring with smaller beams because it puts less stress on the house,
minimizing cracking above which would require additional repairs in finished spaces.
When the basement is accessible to the street we can use our Bobcat or Excavator to
speed up the dirt removal process. In hillside or poor access projects we are sometime
forced to remove the dirt manually (using small jackhammers) which is much more labor
intensive. Sometimes we will use conveyors to help load the dump truck faster, or at use
the Bobcat to move dirt from the driveway or yard to the truck.
Dirt, Dirt and More Dirt
The excavation occupies most of the time in a digout project. The volume of dirt can be
massive, and dirt expands when dug out as well. It is typical to remove a few hundred
tons of soil, often 30 or 40 dump truck loads over the course of 4-8 weeks.
We are blessed in the East Bay with really good soils from a construction perspective.
Clay tends to be stable when dugout, and often shoring is not required, but when soils are
loose or when we are adding gravel drainage after the foundations we will build a
temporary wall outside of the new foundation to hold the soil in place.
Footings Are First
The new basement foundations become giant retaining walls with large footings to
prevent settlement and sliding. Substantial steel reinforcement is a part of this. We often
pour the footings first, then build the concrete walls above them.
Drainage is Critical
Often we install the drainage prior to pouring the wall. By putting in a membrane system
and piping up against the dirt we can use this as one side of our form. The miradrain
membrane functions as a minature drainage system, so gravel backfill is not needed.
Reinforced Floor Installation
After the walls are installed, the reinforced concrete slab is put in. A vapor barrier is
installed below to protect against water, though the perimeter drainage should eliminate
any potential moisture issues..
The Digout is Complete
After the floor is in, the shoring and beams can be removed and the space is ready for the
remodel. In some scenarios, interior beams and walls will need to be put in at key
support points before this can occur.