Abstract: A coating mortar compound for pressure spraying over a surface to be levelled. The mortar compound comprises as active ingredients the following three ingredients: a) hydraulic lime, preferably of moderate hydraulicity; b) Portland cement; c) vinyl acetate dry polymer; and further comprising as filler and the main ingredient in weight of the total compound weight the following single ingredient: d) a mineral filler, preferably silica sand. Upon having been sprayed over a surface to be levelled, the mortar compound remains both permeable to water vapors while enabling scupturing thereof even after partial curing thereof. Various additives may be included to enhance the performance of the composition. These optional additives include: hollow glass or ceramic spheres, a defoaming agent, a water retention agent, a rheological aid, a water repellent agent, a water reducing agent, and an accelerator agent.