Foundations for Bay Area homes, ADUs, and additions.

Most backyard ADU foundations run two to four weeks on site: excavation, forming and rebar, underslab plumbing coordination, inspection, pour, and strip. Hillside lots with drilled piers run longer, and your city’s permit and inspection calendar adds its own time. The concrete itself is walkable in a day or two and reaches design strength at about 28 days — framing typically starts within the first week after the pour, per the engineer’s direction.

On a flat lot with good drainage, slab-on-grade is usually the economical answer: the floor and the foundation in one pour. A raised stem-wall foundation with a crawlspace makes sense when the lot slopes, when you want plumbing serviceable from below, or when the ADU needs to match the main house’s floor height. Your designer’s plans and the soil usually decide it — we build both routinely.

For engineered foundations — hillsides, additions on expansive clay, ADUs in some cities — usually yes, and it’s worth having even when it isn’t required. The report tells the engineer what the ground can carry and how deep piers or footings need to go, which is exactly what sets the design and the price. Guessing at Bay Area clay is how foundations end up settling.

Engineered foundations carry required third-party inspections at set points: rebar placement before the pour, pier drilling, epoxy-set anchors, sometimes concrete sampling. They’re the building department’s proof that the foundation matches the drawings. We build the schedule around the holds, so the work is ready when the inspector arrives and the job doesn’t slip.

Yes. Replacement work ranges from re-pouring failed sections to supporting the structure while a new foundation goes in beneath it. It’s engineering-led and very site-specific — the existing structure, the soil, and access set the approach. If your foundation is settling or cracking, start with a site visit and an engineer’s assessment; we can price from there.

All the time — most of our foundation work is subcontracted by Bay Area general contractors, and we’re used to plan-ready bidding and coordinating underslab trades before the pour. If you’re a homeowner without a GC yet, we can still price the foundation from your plans and work directly with your designer and engineer.