The Mandatory Building Inspection Scheme and Mandatory Window Inspection Scheme have been enforced in Hong Kong by the building authorities. All structural components, including structural sealants on buildings that are more than 30 years old, must be inspected and certified by a registered inspector. The Hong Kong building authorities require a safety factor of at least 5 for structural sealants, but the current test method, ASTM C1392-00, Standard Guide for Evaluating Failure of Structural Sealant Glazing, cannot help the registered inspector to determine the safety factor of the sealant on old buildings because it is not a destructive test in which the ultimate strength of the sealant can be found. To evaluate the structural performance of an aged structural sealant or to find out its safety factor, the ultimate tensile strength of the sealant must be found. The objective of this paper was to study the ultimate tensile strength of an aged structural sealant using a destructive test method. A site deglazing test and H-piece tensile test based on a modified version of ASTM C1135-05, Standard Test Method for Determining Tensile Adhesion Properties of Structural Sealants, were adopted for the evaluation process. Sealant samples were collected from four buildings with a similar age, approximately 30 years old, but the ultimate tensile strengths were found to be very different, ranging from 82.36 to 159.8 psi.