Evaluating Laboratory Measurements for Sound Insulation of Cross-Laminated Timber (CLT) Floors: Configurations in Lightweight Buildings

Abstract

Cross-laminated timber (CLT) floors with supplementary layers or floating floors comprise a common solution in new multistory timber structures. However, bare CLT components provide poor sound insulation, especially in low frequencies during structure-borne sound propagation. Thus, floor configurations in wooden buildings deploy more layers for improved acoustic behavior. Twelve contemporary CLT floors were analyzed after laboratory measurements of airborne sound reduction and impact sound transmission utilizing the following indicators: Rw, Rw, 100, Rw, 50, Ln,w, Ln,w,100, and Ln,w,50 (per ISO 10140, ISO 717). An increase in sound insulation was achieved thanks to added total mass and thickness, testing layers of the following: elastic mat for vibration isolation, wool insulation, gypsum boards, plywood, concrete screed, and wooden parquet floor. The results indicate that multilayered CLT floors can provide improvements of up to 22 dB for airborne sound and 32 dB for impact sound indicators compared with the bare CLT slab. Floating floor configurations with dry floor solutions (concrete screed) and wooden parquet floors stand out as the optimal cases. The parquet floor provides a 1–2 dB improvement only for impact sound indicators in floating floor setups (or higher in three cases).

Acoustic Performance Investigation of a CLT-Based Three-Floor Building

“…The available laboratory acoustic test report provides more details on the investigated floor configurations (see Supplementary Materials). Furthermore, it should be noticed that the acoustic performance of different floors presented in [12] does not meet the targeted performance proposed above.…”

“…It should also be mentioned that within the ongoing "Sound Wood Austria" research project, the acoustic laboratory measurements of typical Austrian wooden building components were carried out in order to determine the effect of various design configurations on airborne and impact sound insulation in a systematic approach and to identify possible optimization potential [11]. Numerous configurations of wooden floors for lightweight CLT-frame buildings were also tested under laboratory conditions in Sweden [12], leading to encouraging results for solving problems of detrimental impact sound propagation in the low-frequency range in lightweight buildings made of CLT components.…”

Vibration and impact sound properties of hybrid steel-timber floor structures

“…Furthermore, lightweight structures like timber or hybrid timber floors often encounter challenges with impact sound insulation [12]. Typically, building standards and regulations rely on laboratory testing for assessing the suitability of floor structures.…”

The effect of junctions and mounting on sound insulation of horizontally adjacent rooms in a CLT building

“…These are accompanied by investigations of airborne and impact sound insulation for various floor assemblies and resilient layers with CLT constructions, as done by e.g. Verdaxis et al [11]. Architects, builders and the public often expect and desire for the wood in CLT buildings to be exposed, which partly is the motivation for this paper.…”