Par. 1. - The building limits of the city of Boston as they now exist shall continue until changed by ordinance, and the city council may by ordinance from time to time extend and define them, and may establish other limits in any part of the city within which every building built after the establishment thereof shall be of the first or second class. This restriction shall not apply to wharves, nor to buildings not exceeding twenty-seven feet in height on wharves, nor to market sheds or market buildings not exceeding the said height, nor to elevators for the storage of coal or grain, if the external parts of such buildings, elevators or other structures are covered with slate, tile, metal, or other equally fireproof material, and the mode of construction and the location thereof are approved by the commissioner. Temporary structures to facilitate the prosecution of any authorized work may be erected under such conditions as the commissioner may prescribe. Single and two-family dwellings not to be occupied and not intended, arranged, or designed to be occupied, by more than two families, may be built of third-class construction or of composite construction in all parts of the city of Boston not included in the building limits of the city as they existed prior to the twenty-second day of September in the year nineteen hundred and thirteen; but no such building shall occupy more than sixty per cent of the area of the lot upon which it is situated, and all such buildings shall be constructed with pitched roofs not less than thirty degrees with the horizontal.

[1914, c. 782, sect. 1.]

Third Class Buildings

Par. 2. - Buildings of the third class in the city of Boston may be reconstructed, altered, enlarged, repaired and extended so as to cover a greater area of land: provided, that the reconstruction, alteration, enlargement, or extension conforms to the requirements of the law in respect to new buildings of like character; and, provided, also, that not more than sixty per cent of the lot is covered.

[1915, c. 352, sect. 1, Special Act.]

[1917, c. 221, Special Act.] [1918, c. 179, sect. 2, Special Act.]