Cost calculations within the construction industry can be performed at various levels of detail. Starting at a very general level using component-dependent cost parameters (eg: cost per cubic meter of gross volume [€/m3]) the calculation can be done in the most detailed method by evaluation the individual cost components (material, equipment and labor) separately for every single task. For the traditional construction operations like masonry or concreting works a lot of information is provided to determine the performance values within a close range. For the field of cross laminated timber (CLT) constructions these substantially basics are not well established yet. The actual calculations are often based on in-house knowledge of timber companies without cross company references. To enhance the calculation basics a modified REFA analysis method (REFA 1984, Schlagbauer, Heck and Hofmann 2011) was conducted to collect on site observation data. The results of the task distribution analysis showed very similar results compared to other construction works on the level activities and interruptions with a mean value of approximately 75 % activities. But at a closer look greater deviations were found as main CLT-tasks have a value of 59% compared to masonry work (38%) or concreting work (51%). This bigger share of main activities within CLT works can especially explained by the high level of prefabrication work but has to be considered within the calculation.