A well-known problem with field testing is that it takes a long time before meaningful and reliable results are achieved. Only when a trial has come to an end the so called average life for the samples in a group can be calculated and compared with other samples. The aim of the present study was to investigate if it is possible to get a reasonable and good estimation of the average life long before a trial has come to an end. In order to get early stage results five early indictors were identified. Values for these indicators were calculated for a large number of trials. Estimated average lives (EAL) were calculated with help of single and multiple regression analyses and compared with actual average lives. The results are presented as ccoefficients of determination (R2) between the different early indicators and the average life of the trials as well as diagrams showing the calculated EAL compared to average life according to the standard EN 252. For some groups of test fields and preservatives the correlation and estimations are very good while they are worse in other cases. The study has confirmed that it is difficult to find a general method, based on early indicators, to estimate the average life of different types of preservative-treated wood tested in field trials according to EN 252. However, the calculation model is promising as in some cases the estimated average life shows a good correlation with the average life according to EN 252, which indicates that further efforts to improve the model seem worthwhile.

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