Section 32. If a schoolhouse in any city has not been provided with a safe and proper egress or other means of escape from fire, as required by this chapter or by pertinent sections of the state building code, within six months after written notice by the local inspector to the owner, lessee, occupant, or agent in charge thereof, the mayor, for the purpose of conforming to the provisions of this chapter or the state building code relative to egress or other means of escape from fire in schoolhouses, may, upon petition of one hundred citizens or taxpayers in such city, authorize the expenditure upon such schoolhouse of not more than fifteen per cent of the cost thereof, payable from any money in the treasury of that city which is not otherwise appropriated.