Foundation excavation for a new home costs $1,500 to $10,000 on average by HomeGuide's national 2026 figures, and $20,000 or more in rocky soil. San Antonio foundations are nearly all slabs or pier and beam, cut into rock on the north side and built on clay on the south and east.
All prices on this page are national ranges from HomeGuide, not quotes from us. In San Antonio, limestone, caliche, black clay, access and haul distance decide where a job really lands. Figures checked in October 2026.
What does foundation excavation cost for a new house?
HomeGuide prices digging a foundation for a new home at $1,500 to $10,000 nationally, with large foundations in rock, boulders or heavy clay at $20,000 or more. That is the excavation alone. A complete slab for a 2,000 square foot home costs $12,000 to $28,000, and pier and beam $16,000 to $30,000.
What does basement excavation cost?
Basement excavation for new construction runs $10,000 to $30,000 by HomeGuide's basement section, and $30,000 to $50,000 or more on rocky or tight sites. An 8 to 9 foot dig in standard soil costs $10,000 to $20,000. The same page's project table shows $1,500 to $10,000, but the basement section is the right figure for a full basement. On north side limestone, plan for the rocky end.
Can a crawl space be dug out into a basement?
It is possible but rare and costly. HomeGuide lists digging a new basement under an existing house with a crawl space at $20,000 to $45,000 or more, for excavation only. It needs a structural engineer, underpinning and permits, and in San Antonio, rock or expansive clay usually make it a hard case to justify.
What does it cost to dig around an existing foundation?
Opening up the ground around a house that already stands runs $5,000 to $15,000 on HomeGuide's excavation page, or $100 to $250 a running foot. Near the beam, digging is done by hand or with a small bucket so the soil carrying the slab is left in place.
How far out from the foundation do you dig?
We dig only as far out as the repair crew needs to work safely, usually a couple of feet past the beam. Deeper trenches are sloped or braced so they cannot cave. The repair company or engineer sets the depth, and in rock we may need to break a narrow strip rather than dig a wide one.
Can you dig beside a foundation without damaging it?
Yes, if it is planned. We open short sections at a time, keep the bucket away from the footing, hand dig the last few inches and do not leave a trench open beside the slab through a storm. On clay, prompt backfill and compaction stop the soil under the beam from drying out.
How deep do footings go in San Antonio?
The engineer's plans and the city's building code set footing depth, so it should never be guessed. Frost is shallow in South Texas, so soil decides it: beams on expansive clay are designed for its movement, and on the north side footings are often cut into limestone or caliche. Additions tie into the existing foundation as the plans show.
What does backfill around a new foundation cost?
Backfill is usually included in the excavation price. If extra material is needed, HomeGuide lists fill dirt at $5 to $25 per cubic yard. Backfill placed in compacted layers keeps soil from settling or holding water against the beam.
Who is responsible if my foundation cracks after the neighbor's excavation?
Whether the neighbor's digging caused a crack is a question for an engineer. Photograph and date the crack, measure it, and tell the neighbor and their contractor in writing right away. If the claim is against your own contractor for a defect in your home, the Texas Residential Construction Liability Act (Property Code Chapter 27) requires written notice at least 60 days before a lawsuit. This is general information and not legal advice.
What does digging for a walkout door cost?
HomeGuide has no figure for a walkout door. The digging is priced like work around a foundation, $100 to $250 per linear foot, and the wall opening must be designed by an engineer. On a sloped Hill Country lot, a lower-level door usually needs a retaining wall as well.
To get a number for your own site, have us walk it first; the price comes in a written quote. Call or text (210) 796-2675.