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The efficacy of Brush-on Remedial Treatments on Radiata Pine Framing: 18-Month Progress report
By Dave Page, Jackie van der Waals and Mick Hedley, October 2010.
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Executive summary
Untreated radiata pine framing timber was exposed to brown rot decay fungi and then treated with brush-on remedial preservatives. Over the 32-56 week exposure period (the last three bi-monthly deflection test assessments), patches of fresh decay mycelium had either developed or expanded in the high moisture content exposure tanks on almost all of the untreated samples, the copper naphthenate samples treated on one or two edges and the boron samples treated on one edge. While mycelium and decay ratings for these groups indicate accelerating deterioration, the deflection test results were relatively constant and changed noticeably in only a few samples in the worst affected groups. There was very little mycelium development on samples held in low moisture content conditions but decay was developing on a few of the control samples or "treated two edges" samples and on wetter samples in the bottom two layers of the stack.
Current assessments suggest that the trial is at a critical stage and that deteriorataion in samples treated only on one or two sides/faces will accelerate from now on.
The decision to extend the trial for a further two years, with assessments at 6-monthly intervals, is sound and is expected to clarify any differences in effectiveness of the two treatments and their application to 1-4 faces.
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