Acoustic Testing of a Pinus Radiata Pole Joist Floor System

The overall aim of this line of research is to develop aneasily transportable system for building six storeycommercial buildings using Radiata for the mainstructural elements. This paper reports on a floorarrangement, with pole joists, that has acceptablesound-proof properties.The objective acoustic testing of the prototype floor,using Radiata pole joists, meets all the acousticalrequirements of the NZ Building Code when it is notcarpeted. This is an excellent result for a hard surfaceflooring system.The construction incorporates features identified inprevious research as maximising the insulation from agiven mass of lightweight flooring and hence we expectthat the subjective acceptability will be at least as highas the best performing construction in that research.The ARC has been a strong critic of the NZ Building Codefor expressing the performance requirements in termsof the US rating system. This system was formulated ahalf century ago and ignores the low frequency rangewhich has become a dominant factor for light timberframe buildings in this era of high-power, wide-bandwidth home entertainment systems. In the absenceof low frequency acceptability criteria – and especiallyfor light timber framed structures – we have argued thatsubjective testing and comparisons with concrete-slabbased floor systems are necessary.Another pleasing feature of the pole floor is that itappears to be of a similar cost to the equivalentprestressed concrete floor. The cost is helped by thepole joists which are $18 per sq.m. cheaper thanengineered I joists.