to the spikes the foregoing description as applied to the form or structure shown in fig1 8 inclusive can be changed or the installation and structure varied while maintaining the principles of the invention reference is here made to fig9 and 10 of the drawings these figures disclose a modified installation in which purlins 80 are again mounted in the structure as in the preceding embodiment the insulating material not shown and the facing layer 82 are run or installed in a direction parallel to the purlins this type of installation serves to overcome a possible mismatch which could result in gaps between the material and the purlins due primarily to an improper and inexact spacing of the purlins in such a case it is conceivable that the support means or hangers such as the spikes would not serve to support the material with the facing layer and insulating layers being run in directions parallel to the purlins this possibility is overcome it is noted from fig9 that support strips 84 are again operatively attached to the facing and the sheet is of such width as to overlap the lower purlin lip 86 in lieu of the use of hanger spikes a hanger as specifically shown in fig1 can be used this hanger generally indicated 88.