Do I need to “vent” my roof with foam?

No. Venting is only necessary with “loose” products like fiberglass that allow air and moisture to pass through; not with spray foam.  Venting is meant to keep air moving so moisture from condensation doesn’t build up on the wall and roof sheathing. But since spray foam doesn’t allow moisture-laden air to pass through it, venting is completely unnecessary. Moisture which is a main cause of failure of building materials, mold growth and “sick building syndrome”. Closed cell spray foam is the best deterrent to “sick building” problems because when properly installed, spray foam will never become a condensing surface for moisture.