15/32 Cat Ps1-09 Square Structural Douglas Fir Sheathing, Application as 4 x 8Used for walls, shear walls where extra strength is needed, roofs and general construction applications Constructed with 5 plies of Douglas fir veneer for higher strength than other rated sheathing panels 5 ply construction for increased panel stability Span ratings on the back of the panel denote the maximum recommended center to center spacing of supports, in inches, when installing the panel