Certificate of Occupancy
At the 177 Huntington Ave Office Building you can still see signs of the old building owner. On the back stairs, at each floor landing is a "Certificate of Occupancy." This is a copy of one of the documents:
Click on image for a larger version.
This particular Certificate of Occupancy defines the max load for all floors in the building as 50 lbs per square foot.
Some information about the Building Code in the City of Boston:
Chapter 479 of the Acts of 1938 as amended, 'An Act for the Codification, Revision and Amendment of the Laws Relative to the Construction, Alterations and Maintenance of Buildings and other Structures in the City of Boston' was passed by the Legislature on June 27, 1938, with the provision that it take effect upon its acceptance by the Boston City Council, whereupon the Council proceeded to hold a series of public hearings on proposed amendments submitted by architects, builders, property owners and various civic organizations.
The act was changed a few years later:
On January 1, 1975, the Massachusetts State Building Code, Chapter 802 of the Acts of 1972, as amended, went into effect in the City of Boston and superseded all previous codes. The Building Department and the Housing Inspection Department were abolished and all powers and duties transferred to the Inspectional Services Department by Chapter 19 of the Ordinances of 1981.
In older building, built before 1975, you will find in one of the stairwells, most likely not a heavy traffic one, a Certificate of Occupancy.