How Much Does a Concrete Foundation Cost? National installation figures published in 2026 run from across several foundation types, based on the published 2026 foundation range. Mid A 2,000-square-foot slab foundation is listed at $12,000 to $28,000 in the 2026 national foundation data. A 2,000-square-foot slab foundation is listed at in the 2026 national foundation data. Excavation for a large foundation can exceed $20,000 where rock, boulders, or heavy clay complicate digging, based on recent foundation excavation figures.