Insulation board with improved performance

A roof assembly, comprising:

• a roof deck;
• an insulation board assembly mounted onto the roof deck;
• and
• a roofing membrane adhered onto the insulation board assembly, wherein the insulation board assembly comprises:
• a foam insulation board having first and second opposing surfaces,
• a woven top single layer facer on a top side of the foam insulation board, wherein the woven top facer is in direct contact with the first surface of the foam insulation board, and the woven top facer defines an outermost top surface of the insulation board assembly, and wherein the top single layer facer has a warp density from 4 to 30 ends per inch or a weft density from 4 to 30 picks per inch and wherein the top single layer facer has a tensile strength greater than 80 lbf/3 inch in both a machine direction and a cross direction, and a tear strength of over 15 lbf in both the machine direction and the cross direction, and
• a woven bottom single layer facer on a bottom side of the foam insulation board, wherein the woven bottom facer is in direct contact with the second surface of the foam insulation board, and the woven bottom facer defines an outermost bottom surface of the insulation board assembly, and wherein the bottom single layer facer has a warp density from 4 to 30 ends per inch or a weft density from 4 to 30 picks per inch and wherein the bottom single layer facer has a tensile strength greater than 80 lbf/3 inch in both a machine direction and a cross direction, and a tear strength of over 15 lbf in both the machine direction and the cross direction, and
• wherein the top and bottom facers comprise no glass fibers.