Foam is great for Arizona rooms and room additions- Foam is great insulation and will eliminate condensation.

Here OSB (plywood) is applied to existing awning pans and foam is sprayed 1 inch thick over that, then coated with white acrylic coating.

In most cases metal edging is installed to the roof area and the foam is sprayed to the metal edge. This not only makes the roof more eye appealing from the ground, but it makes the roof one complete piece, there are no seams or cracks for water to get into.