Incineration and landfilling of waste from the timber industry are practices condemned and unused. The reuse of wood waste as a dispersive phase in composite materials has been the focus of much research to develop new products, mainly for the automotive and construction industries. The wood–plastic composites (WPC) present characteristics, such as moderate strength, light weight, and high durability. Besides, they are inexpensive and sustainable, which make them attractive for innovative design. This work investigates the effect of eucalyptus sawdust, a chemical admixture and silica particles on the physical and mechanical properties of WPC upon a statistical methodology. The silica-particle addition was added by the matrix phase replacement to reduce the overall costs, because the latter is nearly 87 % more expensive. A microstructural analysis was conducted to better assess the variables studied. Results have shown that the composites made with 20 wt. % of sawdust addition, 10/50 US-Tyler sawdust particle size and maleic anhydride addition appeared to have acceptable properties for engineering applications.