Since the early 1700s, the art of coppersmithing has been used to construct watertight roofing systems. For low slope, flat seam roofing systems, soldered locked seams and riveted lap joints are essential for the success of this type of system. However, industry standards for testing and monitoring quality assurance to produce a watertight metal roofing product are vague and are not adequately equated to contractor performance. This paper will trace the development of a soldering quality assurance program developed for historical roofing restoration projects requiring watertight seams.The replacement of the original copper roofing on Kingswood School, Cranbrook Educational Community, a National Historic Land-mark in Michigan, serves as a model for this current research. Designed by noted architect Eliel Saarinen and constructed in 1931, the building's extensive copper roof is a character-defining feature of the Prairie Style structure. Because of the importance of the architectural feature, a quality assurance program during reconstruction was necessary to develop a confidence level that performance of the copper roofing would meet or exceed expectations.Procedures were developed for certifying coppersmiths for flat locked and riveted seams. Standardized field observations and reports were created to provide continuous documentation of the contractor's work. Variables examined in the work included joint geometry and soldering necessary for the production of watertight seams. Field observations include solder consumption rates to ensure adequate penetration of the seam.This quality assurance program is designed to identify crucial aspects of a copper roofing system in order to effectively evaluate compliance with design requirements. The program recognizes the need for traditional artistry while incorporating new technology to improve roofing performance. The methodology presented in this paper can be directly employed to develop standards for monitoring copper roof system construction.