Health & Saf. Code, § 129830

From time to time, as the work of construction or alteration progresses and whenever the department requires, the architect or structural engineer, or both, in charge of construction or registered engineer in charge of other work, the inspector on the work, and the contractor shall each make a report, duly verified by them, upon a form prescribed by the department showing, of their personal knowledge, that the work during the period covered by the report has been performed and materials used and installed are in accordance with the approved plans and specifications, setting forth detailed statements of fact as required by the department.

The term “personal knowledge,” as used in this section and as applied to the architect or registered engineer, or both, means the personal knowledge that is obtained by periodic visits to the project site of reasonable frequency, for the purpose of general observation of the work, and that is also obtained from the reporting of others as to the progress of the work, testing of materials, and inspection and superintendence of the work that is performed between the periodic visits of the architect or the registered engineer. Reasonable diligence shall be exercised in obtaining the facts.

The term “personal knowledge,” as applied to the inspector, means the actual personal knowledge that is obtained from the inspector’s personal continuous inspection of the work of construction in all stages of its progress at the site where the inspector is responsible for inspection, and when work is carried out away from the site, that personal knowledge that is obtained from the reporting of others on the testing or inspection of materials and workmanship, for compliance with plans, specifications, or applicable standards. Reasonable diligence shall be exercised in obtaining the facts.

The term “personal knowledge,” as applied to the contractor, means the personal knowledge that is obtained from the construction of the building. The exercise of reasonable diligence to obtain the facts is required.