42 Pa. C.S. § 5537
All actions to recover any or all damages against any person engaged in the practice of land surveying occurring as the result of any deficiency, defect, omission, error or miscalculation shall be commenced within 12 years from the time the services are performed. Any such action not commenced within this 12-year period shall be forever barred. The cause of action in such cases shall accrue when the services are performed. Furthermore, any action shall be commenced within four years from the time that such cause of action was discovered, but no later than during this 12-year limitation period. In any event, no action shall be commenced after the 12 years from the time that the services are performed. The term "practice of land surveying" shall be the same as defined under the act of May 23, 1945 (P.L. 913, No. 367) , known as the Engineer, Land Surveyor and Geologist Registration Law.
42 Pa.C.S. § 5537