A high performance, light weight construction board includes unique low solids Magnesium Oxychloride binder systems filled, Expanded Polymer Beads (EPB) blended with Expanded Perlite and/or with Coal Fuel Fly Ash. Weight reductions for such compositions by incorporating proteinaceous foaming agents into the binder matrix. The use of Calcium and other alkali earth chlorides mixed with magnesium chloride, or totally replacing magnesium chloride, provides unexpected improvements in binder strength. The use of a unique polymer scrim with felt construction provides improved compressive and directional strength properties while also providing superior board pull and shear properties.