Supplemental reinforcement is calculated when the "unreinforced" stress limits are exceeded, even for the structure types and classes where it is not anticipated by BS 8110. For example, if a class 1 beam has tension stresses exceeding 0 N/mm², it will be marked as having failed the 4.3.4.3 criterion; supplemental reinforcement will still be calculated for the class 1 beam even though the reinforcement cannot solve the failure.