Investigation of methods to evaluate acoustical effects of top-of-wall joints

The gap where the top of a stud-framed wall meets the structure must be sealed to achieve the required fire and acoustical ratings. In the United States, there is no accepted procedure for characterizing the acoustical performance of top-of-wall joints, and most often it is required that the joint be filled with acoustical sealant. One way that different products and sealing methods could be evaluated is by testing several walls with different joint conditions. However, this method is time-consuming, and the reproducibility variations in laboratory testing can make it difficult to evaluate the differences. A test method similar to ISO 10140-1 Annex J was developed, in which the transmission loss per unit length of joint is measured. This could be used to calculate the expected performance of a composite wall/joint system. A laboratory testing program was conducted to evaluate the method. In the first phase, the internal consistency, repeatability, and reliability of the method was evaluated by repeated and varied testing of several joints. In the second phase, the same joints were constructed in a full-sized wall to evaluate the accuracy of the calculations. The results are analyzed and discussed.