As a continuation of a project to develop a large scale accelerated laboratory test for the durability evaluation of materials used in the construction of preserved wood foundations, Hem-Fir plywood panels treated to two retention levels with CCA-C and ACA preservatives and installed in PWF test boxes located at the Ottawa laboratory were examined for durability performance after three years in service. The low retention boxes were dissassembled and panels examined visually for signs of decay and borings were taken for additional microscopic examination.