Mechanical · IRC 2021 §M1504.2
Ventilation Duct Length Table and Elbow Deduction
Table M1504.2 read for a smooth-wall 5 in duct on a 100 CFM fan, with a worked 15 ft deduction per elbow, plus the NL and X cell meanings and the airflow-verification exception.. Referenced to IRC 2021 §M1504.2.
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