Appears unbelievable I know, but I had heard similar figures prior to, like 9 to 1 in Simferopol, not sure I believe that. This is just the suggestion of the iceberg when it comes to flat roofs. Attempt not to wet the tile after application for at least one day. https://Matthiasjakobbecker.com/why-flat-roofs-have-turn-out-to-be-a-well-liked-choice/