Abstract: The invention relates to a method for quality assurance in preferably finger-jointed timber (1), produced in series, with a given minimum length (12), characterized in that each piece, produced within the length (12), is loaded with increasing tensile forces at the ends (5) thereof to a threshold value, below the breaking load for a fault-free timber piece, and the length changes (DELTA 1), changing therewith, are determined over a section, or the whole length of the timber piece (1) and used as a quality criterion for the use, or the further processing of the timber piece (1). The invention further relates to a device for carrying out said method.