In this thesis, the behaviour of glued laminated timber combined with hardwood and softwood lamallae is investigated. The influence of hardwood in the tension and compression zone, in terms of strength and stiffness is evaluated.The basis of evaluation consists of determining the behaviour of beams with various combinations of hardwood solely in the tension zone along with beams with hardwood in the tension and compression zone. The influence of different amount of hardwood for both cases is studied my means of experimental and analytical methods.Experimental data attained by performing bending tests are evaluated for different combinations made from spruce and oak. By comparing the experimental and analytical data an increase in the strength and stiffness in various combinations is observed and potrayed which varies based on different wood species.