I have done TONS of new construction inspections through out the Philly area and can give you some advice, pointers, or (hopefully) even be of help to you.
Roof Decks located on the roof of a building usually require 2 dedicated independent / remotely located exits / exit stairs. Code section 10(13-160-050) (Roof decks on detached single family garages require only 1 exit stair. In some cases, decks located contiguous to a single dwelling unit may not require 2 independent exits. If the dwelling unit has access to 2 independent exit stairs. This issue is subject to code plan review analysis and interpretation by DCAP )