Various accelerated decay resistance trials including small simulated wall units, samples exposed in enclosed tanks and ‘I’ samples in stacks have been explored and used to test the durability of treated and untreated radiata pine framing at Scion since 2001. These testing methods have been established to determine the effectiveness of commercial formulations in preventing decay in framing subjected to intermittent wetting. These are relatively short term test methods requiring a minimum of 12 months testing. Results of these tests have been used to develop suitable preservative formulations and retentions for Hazard Class H1.2 for inclusion in New Zealand Standard for Chemical Preservation of Round and Sawn Timber (NZS 3640). In New Zealand framing hazard Class H1.2 is for timber which is protected from the weather, but with a risk of wood reaching a moisture content conductive to decay. In this communication, we discuss the advantages and disadvantages of these test methods.

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