Field tests of six wood species reputed to have a range of natural durability were installed in ground and out-of-ground contact in the autumn of 2004 and spring 2005 at four test sites in Canada and in the USA, in collaboration with Michigan Technological University. Decay results are reported after five years of exposure. The test sites with the fastest ground-contact decay rate were Florida and Hawaii, while the fastest above-ground decay rate was in Hawaii. In ground contact, yellow-cedar and western redcedar were the most durable, followed by eastern white cedar, larch, Douglas-fir, and tamarack. Above ground in Hawaii, yellow-cedar and western redcedar were the most durable, followed by Douglas-fir and tamarack, then eastern white cedar and larch. An equation was fit to these data. The presence of sapwood appeared to have more impact on the rate of decay in the above-ground test than in ground contact. There was no substantial difference between decay in old-growth and second-growth samples either in ground contact or above ground. In one species the presence of a coating applied to decking had some protective effect against decay.