Apparent impact sound insulation performance of raised discrete floating assemblies on mass timber floors

Mass timber panels are increasingly used in mass timber and hybrid construction projects for efficient off-site construction. Conventional continuous floating concrete toppings often struggle to achieve an apparent impact insulation class (AIIC) above 55 when tested according to ASTM standards. This study explores the impact sound insulation of raised discrete floating floor assemblies on cross-laminated timber (CLT) and dowel-laminated timber (DLT) floors through experimental testing. The study found that a raised discrete floating floor, constructed using commercially available dry materials such as oriented strand board (OSB), cement board, and gypsum board, significantly improved impact sound isolation and reduced the need for thick concrete layers. Interestingly, increasing the thickness of the floating concrete topping from 38 to 100 mm had minimal effect on sound insulation. Instead, cement boards provided an effective alternative, achieving an AIIC rating of 65 and offering a dry solution for improving sound insulation in timber construction.