Abstract: A roof insulator support system includes a plurality of longitudinally extending beams supporting a plurality of regularly spaced, laterally extending purlins of Z-shaped cross section with an upturned lip portion on the lower flange of each purlin. Elongated liner support members, being extrusions of a generally inverted T-shape, are attached to and extend along the bottom of each purlin. Each liner support member is attached to a purlin by the interaction of a clip member which engages the lip portion of the purlin and a clip flange which engages the bottom of the lower flange of each purlin to prevent vertical displacement thereof. The horizontal portions of liner support members on adjacent pairs of purlins support roof liner panels laid between the purlins. A layer of insulation material is laid on top of the roof liner panels and a roof extends over the purlins.