Sustainable composite materials for interior spaces and related methods of manufacture are provided. In one aspect of the invention, the sustainable composite materials include a load-bearing stud. The load-bearing stud includes a plurality of woven burlap layers impregnated with a magnesium oxide resin. The load-bearing stud is formed by creasing a woven burlap sheet to form multiple foldable panels, wetting the foldable panels with a curable resin, layering the foldable panels to achieve a multi-layered prepreg, pressing the multi-layered prepreg to distribute the resin therethrough, compacting the multi-layered prepreg within a mold cavity having the exterior shape of the load-bearing stud, and curing the multi-layered prepreg, wherein the resin includes a mixture of mono-potassium phosphate and magnesium oxide. The load-bearing stud provides a lightweight, dimensionally stable, and environmentally-friendly composite structure to replace lumber studs and metal studs in building constructions.