1010.1.9.4 (2) what doors can have a double key deadbolt

[Brian 2]

When using 2018 IBC 1010.1.9.4 Item 2 allowing the use of a double key deadbolt, the code doesn't explicitly say "exit" doors. It just says "main door or doors". For a vestibule, do you allow the use of this provision on both the interior vestibule door and the exterior exit door? Or just the exterior exit door?

The commentary appears clear that the provision is only for the main exit; the interior vestibule door would be an exit access door.
The locking arrangement is not permitted on any door other than the main exit and, therefore, the employees, security and cleaning crews will have access to other exits without requiring the use of a key.

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[Sifu]

I don't think I have ever seen it on both vestibule doors. Usually outer door only with free egress for the inner door. I would say that your interpretation that the inner door is an exit access door is correct. The intent of this provision is for security, and even though it would only slow things down a little, it is still an added impediment to exiting, and doesn't seem to enhance security any. If they breach the outer door, they can just as easily breach the inner door.

 

[ccollings]

when you say "double key deadbolt" are you saying that you would have to use a key on the interior side of the door as well as from the exterior side?
as you quote from the commentary, my understanding is that any door that is part of a means of egress has to be operable from the interior without the use of a key. for example, automatic sliding doors that shut off after hours, have a thumb turn on the inside so that cleaning crews can use the door in the event of a fire. I don't think there is an issue is your talking about locking an interior vestibule door as well as the exterior vestibule door as long as the doors can be opened from the interior side to permit egress. i've seen this done a lot with banks that have atm machines in the vestibules. after hours you use your bank card to access the vestibule and the atm machine while the interior vestibule door remains locked.