Pennsylvania Statutes Title 53 P.S. Municipal and Quasi-Municipal Corporations § 16594. Building inspectors to examine flues

In addition to the duties now required by law, it shall be the duty of the inspectors of buildings, in the city of Philadelphia, to examine the flues of every building or buildings, in the course of erection or alteration within the limits of said city, and shall require the contractor or builders to so construct the flues thereof that fire will not communicate with the adjacent woodwork;  nor shall any flue be built in any party or division wall, unless the same is more than nine inches thick.