Abstract: An insulation stop for use in buildings, such as a dwelling, having truss type roof, and which is capable of confining any type of insulating material to the area directly above the ceiling, while providing maximum space between the roof rafters and the underside of the roof for full flow of ventilation, to thereby materially reduce the energy required for air conditioning the building, as well as the cost involved. The invention consists of a single sheet, preferably of fibrous material, or which could be composed of light weight metal or plastic capable of being bent and folded. A plurality of such items are utilized to form the insulation stop for a complete building with one such item associated with and disposed in part between adjacent roof rafters.