Plywood Underlayment Specifications Size: 4í» x 8í», 4í» x 4í», 4í» x 5' size available 5 ply veneer core constructed provides firm support Whole piece face with no defects Printed nail pattern Guaranteed not to warp, buckle, or delaminate Guaranteed not to have core voids or core gaps Marine grade glue passes boil test provides added. a) Standard. 1/4í¦ nominal (5.2mm) thickness, tropical hard wood & poplar combi core, light in weight, easy to handle, allow score and snaps with a knife for easier and faster installation b) Premium. 1/4í¦ (6.0mm) thickness, tropical hard wood core, birch/beech face and back constructed, extra thickness stiffness panel, eliminates vertical movement at the seams due to compression of the old cushioned vinyl underneath. Seaworthy export packing, suitable for long distance ocean transportation.