In Gabon, the forest covers about 85% of the territory, which is the second forest potential in Africa. For the economic development of Gabon, the government has decided to ban the export of logs since January 2010 paving the way for local processing and the extension of tropical species in local and regional constructions. However, because of the operating costs associated with primary processing and drying, the debited solid wood used in particular under construction is still very expensive to date. An alternative would be to insert lesser quality species in Reconstituted Solid Wood Beams (RSW) currently used in construction. This will allow to minimise the losses due to sawing, to maximise the mechanical resistance of the structural elements obtained and to control, therefore, the costs of the timber construction considered still high with regard to the immense forest resources available to the country. Major interests referred through the development of RSW are due to the good dimensional stability (drying mandatory for mastery of collage), the absence of significant cracking, machining facilitated by the industrialisation of robotics, and the lack of apparent joints. In fact, RSW are mainly used in temperate countries in the construction of large structures. However, the study of the behaviour of tropical timber in their immediate environment is a real challenge for the prediction of structural responses of these kind of structures. The current study is performed Within the company Ecowood in Libreville, Gabon, in order to investigate the mechanical characteristics of RSW beams made up of Staustia Kamernesis (Niové), of Dacryodes Buettneri (Ozigo) and Pterocarpus Osun (Padouk) for different moisture content. The adhesive used is phenol, suitable for tropical environments. Three-point bending tests were initially carried out on the RSW beams DUO and TRIO without defects. The results show that the fracture toughness of the beams is related to the position of the single lamellae. The most resistant are those where the lesser quality lamellae are in less-solicited areas, this is the TRIO combination Niové/Ozigo/Niové. On the other Part, in order to simulate structural wood defects, these tests were carried out again on beams with initial cracks located at different locations to determine the fracture parameters such critical energy release rate.