The structural sealant glazing (SSG) system was adopted in numerous skyscrapers glass facades since the mid 1980’s in Japan. The SSG facade continues being specified and built due to the proven performance of the past 30 years, through typhoon wind events, annual thermal and humidity cycles and seismic events. This paper reports the SSG performance of in-service facades by non-destructive evaluation and destructive evaluation. The destructive evaluation tested specimens cut from an existing SSG unit in use on a commercial building façade that was 31 years old. This building is currently in use and its facade is the first project using factory glazing SSG with a high modulus structural sealant in Japan. The structural performance of the SSG under long term ordinary office use and the actual climate condition is evaluated. As a result, performance deterioration due to aging of SSG was determined to be negligible. In addition, cyclic movement testing was added to test to the 31-year-old test specimens for additional accelerated durability testing. Results of testing of the aged specimens suggest that performance will remain robust for a significant time in future.