The performance of decking with relatively shallow preservative penetration is currently of interest to standards committees. Fortunately, a variety of non-incised nominal 2 x 4 inch decking was put into test by Forintek's Vancouver laboratory between 1981 and 1985. Two sets of non-incised CCA-treated hem-fir with preservative penetrations close to the new CSA O80 decking standards have remained sound after 10 and 13 years exposure. Material which did not come close to this standard, in terms of penetration or retention, showed early signs of decay. Decking double-vacuum treated with 0.5% PCP, performed better than material dip treated with 5% PCP after 13 years in test. Decking treated with Arquad B-100 at 6.4 kg/m3, by uptake, has performed as well as decking CCA-treated to the new CSA O80 decking standard after nine years. Untreated lodgepole pine has performed better than untreated hem fir after 12 years exposure.