This section is from the book "The Building Code Of The City Of Boston", by City of Boston Building Department. Also available from Amazon: Building Code of the City of Boston.
Par. 1. - Every tenement house of the first or second class hereafter erected shall have in the roof a fireproof bulkhead with a fireproof door to the same, and shall have fireproof stairs with a guide or hand rail leading to the roof, except that in such tenement houses which do not exceed sixty-five feet in height, such bulkheads may be of wood covered with metal on the outside and plastered on metal lathing on the inside; provided that the door shall be covered with metal on both sides.
Par. 2. - Every other tenement house shall have in the roof a bulkhead or scuttle. No scuttle shall be less in size than two feet by three feet, and all scuttles shall be covered on the outside with metal, and shall be provided with stairs or stationary ladders leading thereto and easily accessible to all tenants of the building, and kept free from encumbrance, and all scuttles and ladders shall be kept so as to be ready for use at all times. No scuttle shall be situated in a closet or room, but all scuttles shall be in the ceiling of the public hall on the top floor, and access through the scuttle to the roof shall be direct and uninterrupted. Scuttles shall be hinged so as to readily open. Every bulkhead hereafter constructed in a tenement house shall be constructed as provided for tenement houses hereafter erected and shall have stairs with a guide or hand rail leading to the roof, and such stairs shall be kept free from encumbrance at all times. No lock shall be placed on any scuttle or bulkhead door, but either may be fastened on the inside by movable bolts or hooks. All key-locks on scuttles and on bulkhead doors shall be removed. No stairway leading to the roof in a tenement house shall be removed.
 
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