The effect of the strength prediction accuracy on the evaluated values for the duration of load (DOL) factor was discussed particularly for the engineered wood products. When the dead load for the long term loading test is determined basically by multiplying the stress ratio to the average material strength the DOL factor will be inadequately evaluated. And the wide distribution of the strength properties will cause higher DOL factor. The DOL factor was well evaluated by adjusting the stress ratio of each test specimen by considering the time to failure characteristic of the test specimens.
