All improvements shall be subject to inspection by duly authorized and qualified city inspectors, both during the course of construction and after construction is complete. The inspector shall have authority over the materials of construction, the methods of construction, and the workmanship, to ensure compliance with the working drawings and specifications. The contractor shall provide for reasonable tests and proof of the quality of materials as requested by the inspector. Upon due cause the inspector may require that work be suspended; and due cause shall include weather conditions, questionable materials of construction, methods of construction, workmanship, or nonadherence to specifications and drawings.
('69 Code, App. B, § 10.8)