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. - In buildings less than forty-five feet in height all party walls shall be built to a height at least twelve inches above the roof covering, and shall be capped with stone, cement or metal securely fastened to the masonry. In all other buildings such walls shall be carried thirty inches above the roof.
Par. 1. - Where a wall is finished with a stone cornice, the greatest weight of material of such cornice shall be on the inside of the face of the wall. All cornices of second class buildings shall be of brick or covered with fireproof material, and the walls shall be carried up to the boarding of the roof; and where the cornice projects above the roof the masonry shall be carried up to the top of the cornice and covered with metal, like parapet walls.
Par. 1. - Piers and walls shall have caps or plates, where they are needed, sufficient properly to distribute the load.
Par. 2. - Hearths shall be supported by trimmer arches of brick or stone; or shall be of single stones at least six inches thick, built into the chimney and supported by iron beams, one end of which shall be securely built into the masonry of a chimney or of an adjoining wall, or which shall otherwise rest upon an incombustible support. Brick jambs of every fireplace, range or grate opening shall be at least eight inches wide each, and the backs of such openings shall be at least eight inches thick. Hearths and trimmer arches shall be at least twelve inches longer on either side than the width of such openings, and at least eighteen inches wide in front of the chimney breast. Brickwork over fireplaces and grate openings shall be supported by proper iron bars, or brick or stone arches.
 
Continue to: