Rules for Deduction : No deduction shall be made for openings less than 0.5 sq m in area, and no addition shall be made reveals, jambs, soffits, sills, etc. of these openings. No deduction shall be made for ends of joists, steps, etc. not exceeding 0.5 sq m in area. For openings exceeding 0.5 sq m but not exceeding 3 sq m and when both faces are plastered with same type of plaster each deduction shall be made for one face only, and the other face shall be allowed for…