Performance of naturally durable decks after 15 years of field exposure
R Stirling, D Wong
A decking test of Canadian species considered to be naturally durable was inspected after 15 years of exposure at test sites in Ontario and British Columbia. Based on the materials used in this experiment, Douglas-fir and yellow cypress had the greatest decay resistance, followed by eastern white cedar and western redcedar, and then by western larch and tamarack. All materials tested were more durable than the ponderosa pine sapwood control which had completed failed. Whether the wood came from old growth stands or second growth stands had little effect on decay resistance. Only old-growth Douglas-fir had significantly less decay than second-growth. The presence of sapwood reduced the decay resistance of yellow cypress, eastern white cedar and western redcedar, but did not impact the overall decay resistance of the less-durable western larch or tamarack. An initial coating of deck stain was associated with no change or slightly improved decay resistance.
Keywords: decay, decking, field testing, natural durability