Abstract: A block of insulating material which increases in thickness from one end to a maximum at the other end is used to fill the wedge-shaped recess between adjacent rafters and the junction between the vertical wall and the rafters. In one embodiment it is placed on the flat upper side of the ceiling panel between adjacent ceiling joists and in another embodiment it is reversed and engaged against the sloping roof panel between adjacent roof rafters. In both embodiments, the insulation is blown against the curved surface and the increase in thickness of the pillow maintains a relatively constant R value to the outer surface of the wall.