Acoustic performance of timber volume elements

Abstract

The thesis investigates the acoustic performance of light weight timber constructions known as timber volume elements and vibration insulation methods employed in these. Common materials used in light weight timber floor constructions and different floor configurations consisting of these materials were also studied. The study consists of impact sound and air-borne sound insulation measurements performed on a cross laminated timber floor in laboratory and two vertically adjacent timber volume elements in factory conditions.

This thesis finds that even though elastomer intermediate layers perform better than wood based intermediate layers, especially for higher frequencies. The increase in acoustic performance provided by utilizing elastomer based intermediate layers is not that high if compared to the increased financial costs it brings. From the measurements performed in factory conditions it is concluded that the tested timber volume elements can reach sound classes up to sound class B for impact sound insulation and sound class D for air-borne sound insulation. Air-borne sound insulation did not satisfy requirements for sound class C and therefore limited the overall grade of the timber volume elements. This was however a result of leakage produced by a poor seal on the door of the sending room. With small efforts the grade of most factory configurations could be upgraded to sound class C.

Furthermore it is concluded that for the floor configurations measured in laboratory, the addition of mass provided by the different material layers is the greatest contribution factor to increased acoustic performance.

Popular Abstract

Acoustic solutions for timber based buildings are still being developed and evaluated. While some construction methods yield satisfying acoustic performance others might not be as effective as once thought.
As of 1994 an update of Swedish building regulations has allowed for the use of load- bearing structural elements made of timber in multi-storey housing. The new regulations together with the rising demand for sustainable housing has led to increased research and development of timber based construction
materials. Timber is a more environmentally friendly and sustainable construction material than other frequently used building materials such as concrete. Since the use of timber is rather new, acoustic solutions for timber based buildings are still being developed and evaluated. The cost of correcting an error in a finished building is far greater than correcting it during the early phases of planning. Because of this it is of great importance to analyze existing acoustic solutions to find possible improvements and to identify ineffective construction methods early in the planning phase of construction. This report is made in an attempt to further the understanding of the acoustics of timber based buildings. Timber Volume Elements in particular. A popular construction method in Nordic countries is to use large Cross-Laminated Timber slabs as load bearing elements. The slabs are assembled into modules also known as Timber Volume Elements that can be combined vertically and horizontally to fulfill the desired function of the building. An entire module can be produced in factory settings to later be transported to the construction site where it and other modules are combined to a finished building. For these modular buildings different intermediate layers consisting of elastomers of different stiffness is used to limit the spread of vibrations between adjacent modules. These elastomer intermediate layers increase the cost of production significantly and the quality of their performance over the course of time is in question.In this report several different floor configurations with a CLT base are evaluated in laboratory. Furthermore the efficiency of intermediate elastomer layers between two vertically adjacent timber volume elements are investigated in factory conditions. As a comparison intermediate layers consisting of
wooden planks cut into different shapes are also tested and compared to the elastomer. A floating floor construction is also evaluated during factory measurements. The acoustic performance of both cases are evaluated using standardized measurement procedures.The results of the factory measurements show that elastomer intermediate layers do in fact perform better than wood based intermediate layers but the improvement provided by the elastomer layers are not as significant as expected. Especially if the increased performance of the elastomer is weighed against the financial cost. Factory measurements also show that floating floor constructions are an effective solution for increasing the acoustic performance of timber volume elements.

• author: Olsson, Oliver
• supervisor: Delphine Bard
• organization: Engineering Acoustics
• course: VTAM01 20201
• year: 2020
• type: H3 - Professional qualifications (4 Years - )
• subject: Technology and Engineering
• keywords: Impact sound insulation, Air-borne sound insulation, Cross laminated timber, CLT, Timber Volume Element, Vibration Insulation.
• publication/series: TVBA-5000
• report number: TVBA-5061
• ISSN: 0281-8477
• language: English
• additional info: Examinator: Erling Nilsson
• id: 9020704
• date added to LUP: 2020-06-23 12:29:25
• date last changed: 2020-06-23 12:29:25