A change to the 2018 edition of the International Building Code (IBC) and the International Fire Code (IFC) helps to establish the intent of these codes with regard to roof doors.
The IBC exempts locks used only for security purposes from the mounting height requirement. The accessibility standards exempt locks operated only by security personnel. What's the difference?
Thresholds and gasketing are simple in comparison to other types of hardware, but the code requirements can make them difficult to properly specify and supply.