Ranking Sound Insulation Regulations: Giving New Zealand an International Context

Abstract

Sufficient sound insulation is required between tenancies to provide protection from noise intrusion which otherwise can be a major source of suffering for building occupants. Sound insulation of residential buildings has a key role in providing building occupant satisfaction and health.

In New Zealand (NZ), sound insulation regulations dictate the minimum airborne and impact sound insulation performance between abutting tenancies. These requirements are currently specified in Clause G6 of the NZ Building Code (published in 1992, amended 1995).

In 2010, it was proposed that that the performance requirements be changed. These changes included increased sound insulation, different measurement methods, different sound insulation descriptors (unit) and including a wider scope of building elements, e.g. including services, between common spaces, doorways etc.

Part of the justification for these changes was that they would enable NZ to catch up with ‘international practice’ (2010). However, there is limited information regarding the performance required by sound insulation regulations internationally, other than a small number of studies-based on European regulations.

This research investigates how ‘international practice’ might be established. The research develops a methodology, which enables a comparison of the performance requirements of residential airborne sound insulation regulations. As a proof of concept, this research then pilot tests the methodology, focussing on testing how regulations from around the world would compare if applied in NZ.

Six regulations were selected for the pilot test; The Building Code of Australian; the National Building Code of Canada; the New York City Building Code; the Republic of Ireland Technical Document E and the two versions of the NZ Building Code (1992, amended 1995 and the 2010 proposed changes). The sampled regulations encompass four descriptors and the use of two different organisational bodies from countries across three continents. The regulations were assessed for their airborne sound insulation performance requirements between abutting tenancies. These requirements were then compared to determine which required a greater or lesser sound insulation performance.

Due to the range of descriptors and performance levels of the various regulations the comparison was not a straightforward mathematical one. Instead, computer simulation was used to convert the various performance requirements into the all the descriptors used by the regulations. This was done using construction-based tests. The comparison was based on the regulations being applied in New Zealand. This was carried out using ten different NZ-based construction-types; e.g. double timber stud and concrete pre-cast panel systems.

The comparative regulation performance requirements for each of these constructions were ranked from highest to lowest (with 1st Rank being the highest performance required and the ranking number increasing as the performance requirement decreases). The transmission loss result from each of tests was then used to quantify the difference between the ranks found.

It was found the Australian Building Code required the highest airborne sound insulation of any of the regulations for abutting tenancies (1st rank). This was more than double Ireland’s required performance. This was followed by the proposed changes to the NZ Building Code (2nd), then the current version of the NZ Building Code (3rd); the National Canadian Building Code and the New York codes were ranked 4th equal and finally Ireland ranked last (6th).

The research found NZ (Proposed) requirements were not consistently higher than that already specified in NZ (Current). In some cases e.g. double timber stud construction, NZ (Current) actually requires a higher airborne sound insulation performance. The evidence in this research suggests that the performance requirements of NZ (Proposed) would need to be increased to improve on NZ (Current) across all constructions-types. However, it was the found the findings of the pilot test may be confined only to the elements tested. A full expansion of testing into the comparisons of field units may yield further interesting results and contrast the results found through the design units (laboratory-based descriptors).