Section 26A 1/2. Every building or structure of more than seventy feet in height above the mean grade and constructed prior to January first, nineteen hundred and seventy-five, shall be protected with an adequate system of automatic sprinklers in accordance with the provisions of the state building code; provided, however, that sprinklers shall not be required to be installed in patient rooms in hospitals, or in public or private libraries, or in houses of religious worship; provided, further, that sprinklers shall not be required to be installed in buildings where construction has commenced prior to January first, nineteen hundred and seventy-five and which have been submitted to the provisions of chapter one hundred and eighty-three A; and provided, further, that automatic sprinklers shall not be required in rooms or areas of a telephone central office equipment building when such rooms or areas are protected with an automatic fire alarm system.

The head of the fire department shall enforce the provisions of this section.

Whoever is aggrieved by the head of the fire department's interpretation, order, requirement, direction or failure to act under the provisions of this section, may, within forty-five days after the service of notice thereof, appeal from such interpretation, order, requirement, direction, or failure to act, to the board of appeals of the fire safety commission as provided in section two hundred and one of chapter six.

Any building or structure subject to the provisions of this section shall comply with the following schedule for the installation of automatic sprinklers:— one-third of the gross square footage of the building or structure shall be equipped with automatic sprinklers by March thirtieth, nineteen hundred and ninety-one; two-thirds of the gross square footage of the building or structure shall be equipped with automatic sprinklers by March thirtieth, nineteen hundred and ninety-four; and the entire gross square footage of the building or structure shall be equipped with automatic sprinklers by March thirtieth, nineteen hundred and ninety-eight; provided, however, that the owner of said building or structure may apply to the board of appeals of the fire safety commission for an extension or a waiver of the provisions of this section as provided for in section two hundred and one of chapter six.

Any building or structure subject to the provisions of this section shall have the option of complying with the following schedule: the entire gross square footage of the building or structure shall be equipped with automatic sprinklers by March thirtieth, nineteen hundred and ninety-four; provided, however, that under said option the owner of said building or structure shall be deemed to have waived his right to any such extension of time.

For purposes of this section, the gross square footage of a building or structure shall include the sum total of the floor areas for all floor levels, basements and sub-basements, measured from outside walls irrespective of the existence of interior fire resistive walls, floors and ceilings.