Section 3A. Unless otherwise provided by the state building code, the local inspector shall enforce the state building code as to any building or structure within the city or town from which he is appointed, including any building or structure owned by any authority established by the general court but not owned in whole or in part by the commonwealth, and the state building code shall be the code for all buildings and structures within the city or town. In the event of a conflict between the code and a statute, ordinance or bylaw regulating an historic district, regional historic district or architecturally controlled district, the statute, ordinance or bylaw regulating exterior architectural features within that district shall prevail. The inspector shall enforce the state building code as to any building or structure within any city or town that is owned in whole or in part by the commonwealth or any departments, commissions, agencies or authorities of the commonwealth. The inspector shall have all the powers of a local inspector under this chapter and under the state building code as to buildings or structures that are owned in whole or in part by the commonwealth or any of its departments, agencies, commissions or authorities.

The inspector may review any order or decision of a local inspector. The inspector shall supervise the enforcement of the state building code, make periodic reviews of all local building inspection practices and make recommendations for improvement of such practices. Reports of such reviews shall be filed with the board of building regulations and standards.

The provisions of this section shall not apply to bridges and their appurtenant supporting structures which have been or are to be constructed by or are under the custody and control of the department of highways or the Massachusetts Department of Transportation or for which said department or authority has maintenance responsibility.