Purpose-based sound insulation in buildings with a frame made of CLT

The project focuses on modelling and developing building systems based upon cross-laminated timber (CLT), from a sound insulation perspective. The goal is to present a variety of solutions to be used for schools, offices and homes respectively. Each category is assigned three different suggestions depending on whether sound class BBR, B or A is sought.

The research project runs in 2021–2022 and is a collaboration between LTU - Engineering Acoustics, Martinsons Byggsystem and Tyréns. The main grantor is WoodCenter North.

The interest in using CLT for building is currently great and there is a need to continuously develop and improve the building construction to secure good sound insulation. The concept of "good sound insulation" could also be expressed as "correct sound insulation" because different types of premises require different airborne and impact sound insulation. Dwellings have comparatively high requirements for sound insulation, while they are lower for schools and offices. To use a construction for schools and offices that is known to work well acoustically for dwellings, is oversized. Therefore, solutions optimized for the current area of use are in demand, with a more economical product and increased competitiveness as a result.

The project uses information from different methods to estimate the sound insulation between rooms in various CLT-based constructions. An analytical prediction method based on how vibration energy is spread via junctions to different parts of the building, is used as a basis. In the next step, the effect of necessary additions, e.g. gypsum boards, upper floors and suspended ceilings is estimated. The result is verified through a combination of new (performed within the project) and previously performed sound insulation measurements, both in the lab and in the field. A series of measurements is carried out in a developed two-room setup, with the possibility of both horizontal and vertical measurements.