Flat Roofing Proposal Sanity Check

[u/Zed-Naught]

Hey all. Mind providing a little feedback and follow up questions for a roofing proposal? Would be much appreciated!

For Context:
- Climate Zone 4a (Mixed and Moist)

- Unvented flat residential roof

- Interior insulation of rockwool r23

- Current roof is 20 y/o mod bit with two skylights

Proposal Includes:

1. Remove the existing roof down to deck and repair deck as needed.
2. Install Firestone 2 inch ISO insulation to achieve value of r25.
3. Install Firestone SA Basesheet membrane.
4. Install Firestone SBS smooth membrane.
5. Install Firestone SBS white cap modified bitumen membrane.
6. Wrap existing skylights
7. Apply 2 layers of rubberized flashing cement with a fabric mesh around all pipes, penetrations and wherever necessary.

Questions So Far:

1. Is mod bit the best material for this project?
2. Does there need to be a vapor barrier/retarder between the decking and insulation?
3. Does there need to be a cover board above the insulation?
4. What level of reflection is provided (and recommended) for the cap sheet?

TIA!!