Axiom, they said that they did a precise measurement from a satellite image and they came up with 28.5 square.
I have no idea how they arrived at that number.
I used the architectural blueprints and a tape measure for the ridge heights and then Pythagoras came in handy. They measured from low earth orbit and were way off. I have contacted them for a clarification, though no word.
If I heard that I could be set-up with metal hidden fastener tiles for16.5 square at $550 per square then I would be very happy. From what I can see even asphalt would not be that competitive.