Basement Digouts

If you’re a homeowner in Alameda, Berkeley, Oakland, El Cerrito, and Piedmont, CA.

Common Basement Digout Questions

A basement digout entails excavating underneath your home, building tall foundations equipped with proper drainage, and installing a new floor. This process creates a raw space that can eventually be remodeled.

Why do you need a basement digout?

These are for anyone who wants additional space for whatever reason. In most cases we see this for growing or expanding families or creating rental spaces.

How do we do basement digouts?

Here’s the essential breakdown:

Support your home on steel beams – We start by reinforcing your home on robust steel beams, ensuring a stable foundation for the transformation.
Demolish the old foundations.
Excavate dirt to the new level – Digging down to a new level, typically at 9 feet for an 8-foot tall finished space.
Construct full height foundations with drainage for the new space.
Construct a new reinforced concrete floor.
Add structural framing, beams, etc, to create the desired open space.

Once completed, the space should be a blank slate for any desired remodeling projects, such as bedrooms, family rooms, bathrooms, or any other space that suits your lifestyle.

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.

Excavation

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.

Temporary Shoring

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.