The invention relates to a construction module for erecting flat structures, particularly walls, comprising two parallel panel-shaped wall parts and a module core arranged between them. According to the invention, each wall part has a number of room-height solid squared timbers that are set on end. These squared timbers are joined to one another in an at least non-positive manner via a mechanical pinning placed transversal to the longitudinal direction of the squared timbers and extending in the plane of the wall parts, and/or these squared timbers are each pinned in an at least non-positive manner with at least two crossbars, which extend essentially transversal to the longitudinal direction of the squared timbers and which are located in the future module core.