Abstract: A system for securing a plurality of slabs of insulation to an underlying roof decking substructure by a plurality of batten strips is disclosed, wherein the plurality of slabs of insulation are disposed within a grid-type arrangement comprising a plurality of transversely oriented rows of the slabs of insulation and a plurality of longitudinally oriented columns of the slabs of insulation. Alternative columns of the slabs of insulation are preferably longitudinally offset with respect to the columns of the slabs of insulation which are interposed between the alternative columns of the slabs of insulation so as to effectively stagger adjacent or abutting slabs of insulation with respect to each other for enhancing wind uplift resistance properties.