Recognizing that the provision of safe and sanitary buildings is essential to the welfare of the inhabitants of the City and County of San Francisco, there is hereby established a Department of Building Inspection which shall consist of a Building Inspection Commission, a Director of Building Inspection, and such employees as may be necessary to carry out the functions and duties of said department. The commission shall organize, reorganize, and manage the department. When the commission assumes management of the department, the Bureau of Building Inspection shall cease to exist. Unless modified or repealed by the commission, all orders, regulations, rules, and policies of the Bureau of Building Inspection will remain in effect. Except as limited below, positions in the Bureau of Building Inspection of the Department of Public Works legally authorized on the date the commission assumes management of the department shall be continued, and incumbents therein legally appointed thereto shall be continued as officers and employees of the department under the conditions governing their respective appointments.