As I understand it foam roofs do not leak as the foam is completely water proof and can even be walked on. But I think most folks find them ugly. They are one of he best ways to go for insulation. And they need to be painted every 8 to 12 years. And they are one of if not the most expensive roof you can put on. I have been looking into one for years, for added insulation as I have no attic space to add insulation in. Keep getting turned off by the extreme cost.
No the foam is not completely waterproof. Once they get moisture in them your R-value is gone and it will never come back. There are many reasons they are not used here in the NW. One is better off adding rigid insulation under a real roof.
I agree but even thats gonna be quite costly. The cost of the ridgid insulation alone is pretty high. I have had a number of customers want it until we gave the a cost to do it. We just did one in Newport Beach about 2 months ago, but most folks do not want to pay that kind of $. Time consuming screwing it all down also.