Crib for prismatic columns of the type that has a tubular core (1) defining an inner prismatic housing (2) and an outer cylindrical surface. The core is housed in an outer covering (4), also cylindrical, that stabilizes it. Said tubular core (1) has a waterproof inner tubular coating (6) that is foldable during the storage and transport steps allowing a remarkable volumetric reduction. The outer covering (4) has at least one cut (8) for assembling it on the tubular core (1) at the moment of using the crib so that not additional complementary action is needed except to outwardly web said covering (4) to keep it strangulated according to the prismatic form intended for the column to build. In another embodiment, the stabilizing covering for the tubular core (1) has a casing (4') made by a mesh of fiberglass or any other textile material. Said casing (4') is flexible similar to the inner casing (6) to allow folding the crib during storage and transport situation.