Here are the primary factors that determine the total cost of a basement excavation project.
- Size of excavation: The larger the space you need to have excavated, the more the project will cost.
- Raising or bracing: Raising your home on jacks will be less expensive but also less stable than bracing it.
- Plumbing: Your new basement will need proper plumbing and drainage systems.
- Permits: Local building codes will determine how much you’ll pay in permit costs.
- Foundation: A new concrete foundation will need to be poured under your new basement.
Cost by Size of Excavation
The digging itself is the largest contributor to basement excavation costs since you’ll pay between $75 and $150 per cubic yard of dirt removed. Creating a 1,000-square-foot basement requires excavating about 300 cubic yards, so you’ll likely pay between $22,500 and $45,000 for the digging alone.
Cost of Raising or Bracing the Home
A house needs support when the earth underneath is excavated to create a basement. One way to support a home is to raise it on hydraulic jacks. While this is the quicker and less expensive option at $3,100–$9,400, it also subjects the home’s structure to substantial stress, potentially causing cracks or other damage to the walls, floors, or ceilings. Your home may need to pass structural checks to determine whether it’s safe to raise.
Alternatively, you can have your home braced at each foundation footing while the digging takes place underneath. This process is called underpinning, and it requires more time and labor, so it can add up to $20,000 to the project. However, it preserves the structural integrity of the house so you won’t risk further damage. You’ll want to speak to a structural engineer about the best process for your home.
Cost of Plumbing
In order to make your new basement space livable, you’ll need to install new plumbing. This includes drainage and waterproofing to keep your new basement dry, particularly if you live in an area with a high water table.
- Plumbing: Depending on the fixtures you want in your basement and how the excavation affects the main sewer line, you may pay anywhere from $1,000–$3,000 for plumbing.
- Drainage: The drainage system you need will depend on the local climate and soil conditions, plus the grading of your yard. It will likely cost between $2,000 and $6,000.
Cost of Permits
This major construction project will require building permits no matter where you live. However, the specific permits and their costs will vary based on your city and state. Prepare to pay between $1,200 and $2,000 for permits.
Cost of New Foundation
Once the plumbing is installed, your home will need a new foundation. The cost of pouring a concrete slab for foundation walls, floors, and footings usually costs between $10,000 and $30,000.