53 Pa. Stat. § 24874
Whenever any party wall shall become impaired in whole or in part, or whenever the same shall in whole or in part be unfit or unsafe for the purpose of erecting a new building or buildings upon the adjoining lot, and the owner or owners of said wall, or any one of the same, shall desire to have said wall repaired or shall desire, in whole or in part, to tear down said wall and have erected a new party wall for the purpose of then erecting a new building, any one of the owners of said wall may apply, in writing, to the bureau of building inspection, signifying to such bureau his or their desire in reference to said wall, and it shall thereupon be the duty of said superintendent, or his authorized agent, to examine the same, having given notice as prescribed in this section when said examination shall take place, the said superintendent, or his agent, shall, within six days after said application has been made, decide what, if any, alteration or repairs shall be made in said walls and whether it is necessary that the whole or any part, and if so, what part of said party wall shall be torn down and a new one erected for the purpose of new buildings which either party may then desire to erect, which decision, in writing, shall be final and conclusive upon all parties. The said superintendent, or his agent, shall also determine in what proportion the cost of repairing or of tearing down part or the whole of the old wall and the erection of part or whole of the new wall shall be borne by the respective owners of said lot, which decision shall also be in writing and shall be conclusive upon all parties.
53 P.S. § 24874