Venting, Insulation and material question for flat roof

I have a new flat roof (3/8" per 12") 3 season addition that I have many questions about. It will have PGT® Eze-Breeze® Sliding Panels installed and I need your help with the roof and ceiling. I will have a porch/balcony on top of the the flat roof in the future and want to have the correct roof material to allow the balcony later. There will be more columns installed when the panels go in to support the balcony. What would you suggest for the roof material that will allow a balcony/deck to be added later? Also I will be putting up pine bead board on the ceiling and would like your suggestion for insulation and vapor barrier.
I will have to run stryofoam chutes to the 6/12 roof as their are 2 roof vents that will need to be vented. I will have soffits vents for this as I have the i-joist on 2x’s sitting on the LVL’s. I cut the 2x’s to allow air to get to the chutes.

Any and all suggestions all welcome


Is anyone willing to provide some answers to my questions on this project?

Certainteed flintlastic 3 ply system. You will need to go 18 inchs under the shingles. And also add apron flashing.

you need an EPDM system with sleepers flashed into the rubber. i just saw an episode of this old house like a week ago that they did exactly what you are talking about. maybe you can find the episode online. it is quite a complex thing to explain on a forum.

Seal off the flat roof, insulate with batt to R30. Install vents in the second layer of shingles on the 6:12 to get air into the attic space.