All of the necessary expense insured in and about the performance of the duties named in this section, including the preparation of plans and specifications, survey and draughts, shall be borne and paid by the person or persons at whose instance and request the work shall be done, which expense may be computed in determining the final cost of such party wall. All sums of money so paid shall be returned to the city treasurer of such city by the public officer receiving the same.
53 P.S. § 24877