But why?! Hasn’t there been enough lessons learned through moisture/mold construction litigation in the hospitality, multi-family apartment high rise, student and military housing sectors that show that dumping the make-up air to the corridor is a risky proposition? Apparently not?! This concept of make-up air delivery to a corridor has been and continues to be a living unit moisture and mold risk because the make-air cannot reach each occupied room on each floor for purposes of ventilation, pressurization and make-up air for exhaust. Many times, it is intended that this makeup air will reach each occupied rooms across each room’s door undercut. But it can’t because resistance to airflow, the amount of required makeup airflow to each room, the size of the door undercut, and the internal and external pressures on the rooms and corridor. In addition, test and balance can’t accurately measure it.