Recommended thickness of plastering for brick walls is 12 MM, 15 MM or 20 MM. (a) 12 MM thick cement plaster is done where the plain surface of brick masonry is plastered. (b) 15 MM cement plaster is required on the rough side of 9" and 4.5" wall. (c) 20 MM thick cement plaster is done in two coats in some cases on rough side of wall or according to the design requirement.