Foam board insulation good enough

[Slimjim6100]

I built a pole building last fall, it's 32x40x13, 2 insulated 12x12 doors with r13. When it was built they put a metal ceiling in with r19 bats. I'll probably end up blowing more insulation up there eventually, but I want to get the walls done first. I can get seconds poly iso foam board for a decent price and was wondering if 3 inch would be good enough for the walls and seal it all up with spray foam. I plan to finish the walls with metal to. Doing spray foam is not an option. The quotes I got were not affordable at all. I did have them house wrap the building before putting the metal on the sides. I live in pa and plan to keep it heated in the winter.

Also have 2 inch foam in slab

 

[jack stand]

I used "reclaimed" foam also and would again.
16 years ago a 4x8x1 1/2" sheet was about $7 and that was polyiso, same r value as cloaed cell spray foam. I put a horizontal layer between the wall girts outside oftheframing (under the metal) and the walls were 16" o.c. and it got a vertical layer that left room for r13 fg in the 2x6 stud bay. Canned foam sealing the edges and any joints.