Hi. 

Double door fire exit has one leaf out of order. The fire exit serves area of building that's disused but could still be used by contractors. Leads from disused auditorium. Is it better to fix the faulty leaf or ok to have one leaf out of action?  Regs refer to occupancy factor going through exit and now the area is disused, only contractors and any staff that's gone into area in this area now. 

Unless you are going to have more than 60-100 people all checking the same area  and needing that exit I wouldn't worry! Securing the doors is more important to prevent trespass that can lead to arson or accidental fire by squatters (commercial premises don't have the same protection that domestic premises now have against squatting so can be more popular as it's not criminal in these premises)