Abstract: A ventilation method and apparatus is described for use in building structures to improve or define ventilation air space. The method and apparatus may be deployed from one side of a structure to penetrate through the structure to displace insulation or improve or define air space for ventilation located on the other side of the structure. The structure may be any structure such as, but not limited to, roofs, walls, floors, cavities, or structures with internal moisture production. For structures which are enclosed with limited or no access to inspect or modify or remedy the ventilation, such as a cathedral ceiling and roof assembly structure, this method and apparatus provides a previously unavailable alternative of modifying or improving or defining the airspace and ventilation, performed from an outer position in relation to the structure.