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Timber framework has become the most common construction technique in the world for private dwellings. In Belgium, although masonry construction still constitutes the most important market share, the number of new houses with timber framework increases each year. Unfortunately the acoustic insulation of this construction type compares unfavourably with traditional masonry construction. In order to learn more about acoustic performance of timber framework houses and to compare them to the performance of traditional masonry houses, a measurement survey has been carried out, on fifteen single family dwellings with timber framework or heavyweight wood. This paper presents the results of the in situ measurements. The measurements were of façade sound insulation, sound insulation of the inner walls (horizontally and vertically) and impact noise insulation. Similar measurements also have been carried out on houses made of traditional masonry in order to compare the results. A comparison of the results collected in the laboratory and Belgian comfort criteria are also presented. Finally, results of acoustic tests in a multi-family timber construction are presented. The weaknesses of construction techniques observed during the study are discussed.

An extensive measurement survey of timber floor constructions has been carried out by the acoustics laboratory of the Belgian Building Research Institute [1]. The basis of this study was the airborne and structure-borne sound insulation measured on a bare joist floor with OSB (Oriented Strand Board) sub floor. By adding different floor toppings and gypsum board ceilings to the basic floor construction, gradual improvements were recorded. A large number of floors are evaluated in the laboratory and formed a database for parametric studies. Improvements due to cavity absorption, floating floors and suspended ceilings were quantified and ranked by effectiveness. Measurement results revealed remarkable differences between floating floor systems. In addition, sound insulation measurements have been performed on joist floors with concrete toppings. The so-called mixed concrete-timber floors provide a higher mechanical resistance. The effect of the bonding and topping type on the airborne and structure borne sound insulation has been examined in the laboratory. The results of this additional research are briefly compared to traditional floor systems and compared with the (future) Belgian standard values. An overall evaluation of the acoustic relevance of timber floor partitions in and between dwellings is also made.

The vibration reduction index Kij expresses the attenuation of the vibrational power flow through a junction. This quantity is important because it determines the contribution of the flanking transmission to the global sound transmission between rooms. It is used in acoustic building prediction models like that proposed in the standard EN 12354. Currently a draft exists to measure the Kij in laboratory. This draft, the prEN 10848, was prepared by the Technical Committee CEN/TC 126 and has been submitted for parallel enquiry. There are also prediction formulae available for the Kij, which are included in Annex E of the standard EN 12354-1 (2000). This article presents the Kij measured in a laboratory according to the draft prEN 10848 and documents an investigation in order to validate them for rigid junctions and junctions with a flexible interlayer. The observations focus on the comprehension and the quantification of the influence of some parameters like the modal overlap factor, the number of modes and the workmanship on the accuracy of the results. Furthermore, an extensive discussion tackles the problem of the determination of the parameter f1 used in the prediction formulae for junctions with flexible interlayers and the effect of the applied load.