This report contains three draft papers concerning field test data. The first paper, "Modelling data from stake tests of wood preservatives," presents a simplified method for using such data. The second paper, "Using stake test data in wood preservation standards," provides a number of examples of how this method can be used to draw practical conclusions from such data. The third paper, "Performance of preservative-treated veneered composites: 1993 data," discusses the effect on performance of using preservatives in plywood and LVL rather than solid wood. Before any substantial change can be made to standards, data must be generated in support of such a change. In the case of wood preservatives the most important part of the data package is the performance in field tests. The standard method for interpreting stake test data is seldom used because it is somewhat unwieldy. What was needed was a simplified method which would be easily understandable by industry, academics and other standards committee members alike. Regression lines have been fitted to plots of decay rating against time for a range of preservative retentions. The slope of these lines was then plotted against retention using a log-log transformation. A rate of decay can then be determined for any given retention. This method has been used to compare the efficacy of different preservatives, compare the effect of wood species and evaluate the extension of service life resulting from increasing preservative retention. The model developed shows an excellent fit to the data from most of the waterborne preservatives in tests. Comparison between preservatives can be made on the basis of the retention required to give the same decay rate as 6.4 kg/m3 of CCA-C. For ACC this was 8.2 kg/m3, virtually identical to the retention specified for this preservative in the AWPA C2 standard. Increasing the retention of CCA from 6.4 to 9.6 kg/m3 increases the estimated stake service life (time to a rating of 70) by 54%. The effect of wood species can be assessed by determining the retention required to give the same decay rate as a standard retention in a standard wood species. For example, aspen was projected to require around 24 kg/m3 CCA to give the same decay rate as 6.4 kg/m3 in ponderosa pine. Using the methods developed here, retentions for new preservatives can now be suggested based on a practical comparison to already- standardised preservatives. There are indications that the higher retentions specified for PWF plywood and lumber will indeed provide the extended service life required of this system. Conventional stake tests use solid pine sapwood which treats through and through. In contrast, treatment of plywood commonly results in a patchy distribution of preservative. The influence of this preservative distribution on performance needed to be determined. The impact on performance of changing wood species and of field cut preservative application also needed to be addressed. Test stakes were cut from commercially treated plywood made from hem-fir and Pine-spruce. Some of this material was installed in a field test 14 years ago with and without field-cut preservative treatment on the edges. The hem-fir plywood was CCA- or ACA- treated. The pine-spruce plywood was CCA-treated. CCA- and ACA- treated aspen LVL was also put into test. Hem-fir plywood with the same preservative retention but a range of degrees of preservative penetration was installed in a soil-bed test. Despite small areas of untreated wood in the outer plys, hem-fir plywood has performed as well as solid wood treated to similar retentions over 14 years in test. Failure to apply field-cut preservative will substantially reduce the service life of preservative-treated plywood. Pine plywood with heartwood face veneers and field-cut treatment performed as well as hem-fir plywood. Plywood with sapwood face veneers did not perform as well. Variation in degree of preservative penetration has shown no effect on performance after 2.5 years in a soil-bed tests. Aspen LVL will require extremely high preservative loadings if it is to be used in exterior exposure. The data on plywood performance continues to support the recent modification to the CSA O80.15 standard to allow small areas of untreated wood in the outer plys. With further data, pine-spruce plywood might be considered for some applications where preservative treatment is required.