Foil-faced or Fiber-Faced Polyiso Exterior Insulation (Climate Zone 6) – GreenBuildingAdvisor

I’ve been perusing the forum and can’t seem to find a straight answer. Located in Maine (climate zone 6). I’m looking into ordering some reclaimed polyiso foam board for exterior insulation but it is fiber faced and I am not sure if it will work well in my wall assembly. I was planning to do 3 inches using two 1.5in layers.

1. Interior wall will be pine tongue and groove (not planning to do drywall)

2. 2×6 construction

3. R-23 rockwool batts

4. ZIP sheathing (7/16in)

5. 3in polyiso (two layers 1.5in, seams staggered)

6. 3/4in rain screen

7. Wood siding (likely pine)

I’m concerned about permeability with the fiber faced polyiso insulation. With the ZIP sheathing, I already have a WRB. Based on what I’ve read it sounds like I would need the WRB on the outside of the polyiso if it was fiber faced. Is this the case? Would foil faced insulation be a better option here? Also, is there any advantage to doing two layers of foam or should I just do one 3in layer?

Thanks in advance.