Fir Texture 1-11 grooved channel plywood is a great choice for exterior siding projects. At ⅝ in. thick with a rough sawn finish, Texture 1-11 siding offers a rustic appearance, and Fir T1-11 offers superior strength and durability compared to pine panels of the same type. This panel has channels that are spaced 8 in. center to center on the face.