The invention relates to a method of manufacturing a prefab construction element (11), preferably a load-bearing element, for frame construction, such as wood frame construction, comprising the steps of providing a roofing, flooring or wall panel (2), which panel (2) comprises an enclosure (3), providing a fungus and a substrate, introducing or preparing a mixture (10) of the fungus and the substrate, in the enclosure (3) and allowing the fungus to grow to form a network of hyphae through the mixture (10) and into the walls (4-7) of the enclosure (3) to form a mycelium composite, and drying the composite while it remains in the enclosure (3) of the panel (2).

A roof panel system including a plurality of roof panels, a plurality of side edge bracket systems and a plurality of end edge bracket systems. The plurality of roof panels are joined end to end and side to side by way of the side edge bracket systems and the end edge bracket systems.