I'm going to convert my screened porch to a 4 season room. It has a gable roof and is open to the living area. To properly insulate it, I was planning on vented soffit, ridge vent, insulation batts and ventilation baffles. How many baffles do I need? Between each rafter?

Also - do they need to go the length from soffit to ridge vent, or will one section at the bottom suffice?

I'm putting T and G right onto rafters for the finished ceiling.

thanks.