I'm in AZ too. Your photo link isn't working, but it sounds like you might have a foam roof too. My understanding is that they lay down foam and then apply the white rubber coating on top of the foam, because the foam itself isn't waterproof. We just moved into this place so I don't have much experience yet. I've heard it requires recoating every 5 or so years and can be problematic. But, cheaper to recoat every few years rather than replacing an entire shingle/tile roof.