Panel for making retaining walls of concrete formwork, in particular for concrete slab retaining formwork or the like, which panel comprises at least one plate (10) of wood or comprising wood, which plate (10) of wood is coated in at least some areas, preferably on its outer faces and/or along its edges with a waterproofing and/or protective coating (2, 310) and wherein the wood plate (10) is formed of at least one layer (210) of birch wood that is arranged in relation to the longitudinal directions and in width of the panel with the wood fibers in a first direction and at least one layer (110) of fir wood that is arranged in relation to the longitudinal directions and in width of the panel with the wood fibers in a second direction, said two layers of wood (110, 210) being coupled together by chemical/physical adhesion along the faces of mutual contact.
The invention also has as object a formwork provides for at least one, preferably some or all of the panels having the above-mentioned carateristics.