Who can legally build a room addition in California?
New square footage attached to the house: foundation, framing tied into existing walls, roof, and extending electrical, plumbing or heating into the new space.
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Licensed for this work
Additions are structural, multi-trade work on a residential building — a B General Building job. (§7057)
Looks like it should cover this — but doesn’t
An addition needs a new foundation, framing tied into load-bearing walls, and electrical, plumbing or heating extended into the new space. A B-2 may do none of those: no structural alterations, no installing or extending systems. (§7057.5)
Licensed for part of it — not the whole job
Specialty contractors may perform their own trade on this job as subcontractors. Any specialty not listed is in the same position.
Site work — grading, drainage, trenching — but not the structure. (§7056)
Basis: B&P Code §7057; B&P Code §7057.5. A California contractor may only contract for work within their classification (B&P Code §7059), with an exception for work incidental and supplemental to their own trade (16 CCR §831). This page reads the classification rules; it is not legal advice and says nothing about quality of work. Confirm with CSLB before signing.