Abstract: A method and a clip system for installing insulation on the purlins of a sheet metal roof construction is disclosed. The clip is of one-piece resilient construction and of a shape to be snapped over a portion of an insulating blanket and the upper portion of a roof purlin to snugly clamp the engaged portion of the blanket against the top and upper opposite sides of the purlin. The blanket is thus contained by the clips below the tops of the purlins so that a pocket suitable for the reception of an unfaced batt of insulating material is formed in the top of the blanket between adjacent purlins. The top of the clip may be provided with suitable means, such as adhesive or projecting barbs, for positively retaining a board of insulating material such as that sold under the trademark, above each purlin and retaining the board against movement during the assembly of overlying roof panels.