Section 3Q. Notwithstanding any other provision of law to the contrary, the provisions of this chapter relative to the safety of persons and the prevention of fire in convalescent or nursing homes, rest homes and charitable homes for the aged licensed under the provisions of section seventy-one of chapter one hundred and eleven, including the regulation of the inspection, materials, construction, alteration and repair of such homes, shall be enforced under rules and regulations promulgated by the division and the board. Except in the case of new construction addition, alteration, such rules and regulations may provide for the installation of a sprinkler system where, after hearing, the division finds such system necessary for the safety of persons; provided, however, that where a sprinkler system would be unnecessary or impractical because of the location, size or construction of a home or because the home is authorized to contain not more than twenty-five beds, the division may require alternative methods of fire protection. An automatic sprinkler system shall be provided throughout any newly-constructed home, and in the case of any existing home where the licensee proposes an addition or alteration, as defined in the state building code, an automatic sprinkler system shall be installed in the course of such addition or alternation to such extent as the division may direct in accordance with such rules and regulations.