Abstract: A system of construction based on the use of polystyrene boards for constructing partition walls as well as extradoses, these said boards being equipped with grooves for electrical and plumbing ducts, as well as for the formation of structural ribs, while their vertical edges are equipped with grooving and tonguing for their interconnection. Boards are put into place between the floor and ceiling, with the interposition of perimetrical perimeter strips made of the same material. Plaster with an additive is then used to coat the surfaces of the said boards as a finish which forms an adhesive paste. Vertical fixing strips facing each other on opposite sides play a role in the emplacement of the boards, while plastic mesh is placed at the joints between the boards and walls, to improve the joint and prevent cracks.