Experimental study on the indication method of heavy-weight floor impact sound insulation performance of CLT floors in Japan

The Housing Performance Indication System provides standardized evaluation criteria for the acoustic performance of residential buildings in Japan. For heavy-weight floor impact sound control, two primary parameters are used: the heavy-weight floor impact sound control grade and the equivalent slab thickness. The equivalent slab thickness quantifies the effectiveness of a floor in reducing heavy-weight floor impact sound transmission, expressed as the thickness of a homogeneous concrete slab with equivalent performance. Current prescriptive regulations define section specifications for timber framework and wood-framed construction, specifying an equivalent slab thickness of 11 cm. The CLT floors, however, have not yet been formally incorporated into these regulatory standards. To address this gap, an experimental study was conducted using two full-scale CLT test houses to assess the acoustic performance of different CLT floor configurations. The results indicate that adding a 100 mm concrete topping and constructing a dry-type double-floor structure significantly enhances heavy-weight floor impact sound insulation, achieving an equivalent slab thickness of 11 cm. This paper provides an overview of the Housing Performance Indication System, outlines the experimental methodology, and evaluates the acoustic performance of CLT floors. The findings support the future development of prescriptive regulations for CLT floors in building acoustics.