Legal Question in Real Estate Law in California

Re: Room Addition

First, it is not unusual to find a discrepancy between assessor records and reality. In dealing with older properties in Sonoma and Marin Counties, I find assessor records to be highly unreliable as to square footage, date of construction, number and type of rooms, type of heat, presence or absence of pools, air conditioning, etc.

The lack of permits will have an impact on your appraisal, but a good appraiser will not totally discount space built without benefit of permit (at least in counties I'm familiar with) because non-permit work is so prevalent and buyers (like yourself?) don't always find out, or care.

Can you demand compensation from someone? Possibly. A seller should disclose illegal or non-conforming conditions they know about. It would be a defense that disclosure was made, or that you knew or should have known from observation that the construction was not permitted.

Your question asks about responsibility for verification, however. The contractor (if used) was responsible for getting the permits in the first place. The selling owner and his agent were responsible for disclosure of the lack of permits. Your agent, then, would have been responsible for verification, and perhaps you yourself, but the law would probably not penalize you for lack of diligence (caveat emptor) because the seller and the agents have a responsibility to protect you.

If this is a big enough deal to consider suit, you should consult a lawyer soon, just in case there is a statute of limitations problem.