Lap-joints made from Southern yellow pine treated with ACQ, DDAC or Propiconazole were exposed and sampled over 12 months. TnBTO treated Lap-joints were later exposed as a standard treatment. The moisture content of the joint area remained at 23% to 28%, but, away from the joint, varied between 20% to over 30%. Untreated samples had higher moisture contents and there was little difference between upper and lower members in all joints. Visual assessment, according to pr ENV 12037, indicated no failure but control samples were deteriorating internally, remote from the joint area. ACQ and Propiconazole treatments performed well, but, DDAC samples less so with regard to discoloration. Discoloration was less apparent in joint areas than on the external faces. Basidiomycetes had become more common at 12 months than previously, mainly on untreated samples. Mould and bacterial species were isolated less frequently on all samples after 12 months. Preservative tolerant organisms included Phialophora sp. (on ACQ), Aureobasidium pullulans (on TnBTO) and various bacteria on all treatments. Different microflora patterns could be clearly distinguished for each treatment.

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