A spacer device is provided including (1) a body having a plurality of openings defining an openwork, to allow the passage of air therethrough when placed in contact with insulation material, and (2) a plurality of spacer struts fixedly attached to the body. The struts are configured to maintain a predetermined distance between a first side of the insulation material and a building surface. The body and struts act together to define and maintain a space between the first side of the insulation material and the building surface, for example, for ventilation. The building surface can be the bottom face of a roof, an attic floor, wall sheathing or a soundproofed demising wall, for example. The spacer device can be capable of being transported and stored together with, or as a separate item from, the insulation material, and can also be stored in nested layers. The device can also be stored in rolled form. The openwork of the device can additionally or alternatively include a sheet of entangled net filaments.