Review of apartment sound transmission requirements could have big impact on building costs


Clause G6 of the New Zealand Building Code deals with the requirements for limiting sound transmission between apartments intended for permanent living.

It was first put in place in 1992, and various attempts to have it reviewed since 1999 have stalled. The problem seems to be that a review is carried out by a panel of experts usually heavily weighted with acousticians who are strong on theory but light on the practicalities of coalface construction and cost implications.

Recommendations from the panel’s review are put forward for public consultation and then the reality of what is proposed comes back as unbuildable, unaffordable, or a combination of both. Ultimately, the review gets shelved as too difficult.

Hence, this particular code clause has been continuously under review since 1999, with no apparent practical end in sight.

In fact, the review has been going on so long and handled by so many different parties that it would be questionable if the Ministry of Business Innovation and Employment (MBIE) has much institutional memory as to what has happened previously, or even why they might be reviewing it.

The latest attempt to review G6 may come out for public consultation some time in the next six months or so, but there is no clear indication of this.

If you are in the business of designing, building or owning any building that has a requirement for intertenancy sound provisions then you should take a keen interest in what is proposed when this review emerges.

I say this, as it appears the same cycle of theory-driven solutions will be wheeled out and, unless very robust, practical feedback is given, the industry could be saddled with expensive and impractical solutions.

Among changes mooted are a shift to more specific design, site testing, and the extensive use of floating acoustic floors in lieu of traditional soft floor coverings in multi-level apartments and retirement complexes.

As the design and testing of these proposed solutions will need the services of an acoustician, the review could be seen as somewhat self-serving.

I also understand the review is being based on European research, mainly Scandinavian, where climatic differences mean the inhabitants are indoors more often and have very different lifestyles to those experienced in New Zealand.

So what should happen from here? Or do we just continue this ongoing cycle of theoretical reviews with practical implementation reality roadblocks?


Downstream impacts could be severe

A bad outcome would be that the MBIE gets impatient, having made little headway since 1999, and becomes tempted to push out untested solutions to get it off their desk.

However, the downstream impacts to this action could be severe on the industry and home owners as they grapple with impractical and unaffordable outcomes.

The effects of sound transfer can be very subjective, and it is quite often tempered around the expectations of the occupants. Some occupants will be very happy whilst others feel severely impacted by even the slightest sounds from adjoining neighbours or surrounds.

To go from a good solution to the very best solution may actually be cost prohibitive and unnecessary for the majority of applications.

A sensible approach to solving this issue would be to first conduct New Zealand research to identify if there is a problem with sound transmission, where that noise is typically coming from, and what size that problem is — and then run a cost-benefit analysis on any solutions that might be deemed fit to solve the problem.

Once research data relevant to New Zealand conditions is available, you can then set about solving the problem if, in fact, there is one.

For an outcome that gives you certainty you would set up a balanced panel of experts comprising acousticians, designers, builders, developers and property owners to work out pragmatic solutions that will be adopted as buildable and affordable.

You would test these solutions in the real world to iron out any glitches and then adopt these as acceptable solutions within the code, thereby cutting out the added cost of bespoke design and testing.

You could also have different levels of solutions that would obviously be at different price points which would help with the affordability issue and customer expectations.

Setting the bar at a theoretically high point may not be the answer for New Zealand’s unique environment.

I urge the regulators to fully understand the problem and proffered solutions, along with the downstream consequences, before imposing more cost on the consumer.


• This article contains the author’s opinion only, and is not necessarily the opinion of the Registered Master Builders Association, its chief executive or staff.

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