An addition foundation isn't a standalone pour — it has to tie into your home's existing foundation correctly so loads transfer the way your structural engineer intended, whether it's a single room or a second story.
Every addition foundation has to match up with a foundation that's already there — different age, different soil settlement, sometimes different foundation type entirely. Second-story additions add another layer: the existing foundation and footings may need evaluation to confirm they can carry the added load before new construction starts above. We treat every addition as its own engineering problem, working from your structural engineer's plans for exactly how the new and existing foundation are supposed to connect.
New footings and foundation sections for single-story room additions, engineered and poured to tie into your existing foundation correctly.
Foundation and footing evaluation and reinforcement where an existing foundation needs to carry the added load of a second-story addition.
New-to-existing foundation connections engineered so loads transfer the way your structural engineer's plans specify, not improvised in the field.
Slab-on-grade or raised stem wall foundation sections for additions, matched to your existing foundation type or your engineer's specified transition.
We coordinate the city foundation inspection and hand off a cured, documented foundation ready for framing — including our own framing crew if you book that with us too.
Based in the Bay Area, working throughout Santa Clara, San Mateo, Alameda and Contra Costa counties.
Not necessarily — your structural engineer will specify how the new foundation should connect to your existing one, which sometimes means a different foundation type with an engineered transition. We build to whatever that plan specifies.
Often, yes. Adding a second story increases the load on your existing foundation and footings, and your structural engineer will typically require an evaluation and possibly reinforcement before the addition can be permitted. We coordinate that work as part of the project.
Addition foundations usually involve more site-specific engineering for the tie-in, and sometimes more careful excavation to avoid disturbing your existing foundation. We give you a written estimate based on your specific plans rather than a per-square-foot rule of thumb.
Yes — this is common. We coordinate directly with your GC's schedule so the foundation phase doesn't hold up framing and the rest of the addition build.
You'll need a structural engineer to specify how the new and existing foundation connect — we build to those stamped plans. If you don't have one yet, we can point you to engineers we work with regularly.
Tell us what you're building — a new home, an ADU, an addition — and we'll get back to you with next steps, usually within one business day.
(925) 592-7162
ProHomeFoundation
