Georgia-Pacific’s DensDeck Roof Boards can be used in myriad roofing systems for new and re-roof applications as cover boards, overlayments, and underlayments. Their fiberglass mats enable the boards to withstand delamination, deterioration, warping, and job-site damage. Other qualities include fire-resistance, strength, moisture-resistance, and dimensional stability. Roof boards are 4 feet by 8 feet and have thicknesses of 1/4, 1/2, or 5/8 inch.; 800-225-6119.