There is renewed effort in reducing the carbon footprint of conventional building materials by employing novel phosphate cements. This study investigates the influence of industrial aggregates, namely fly ash, silica fume and calcium carbonate on biocomposite properties. The biomaterials used included pine, bagasse and wattle. The density of the boards produced ranged from 0.82 to 1.16 g/cm3, and the MOE ranged from 410.57 to 1737.87 MPa. The study concluded that biomass type, curing temperature and aggregates have significant effects on the biocomposite properties. The boards produced met the physical property requirements for use as non-load-bearing structures in humid and external conditions.