This is the correct way to roof an almost flat patio. This customer installed their own patio last year and within months of the install they had leaks. They installed the cover using traditional steep slope shingles with no additional preparations due to the roof being almost flat. We remove the shingles and underlayment and installed a CertainTeed Flintlastic 2 part roll roofing system as well as re-roofing the house in CertainTeed Landmark Moire Black using the CertainTeed Integrity Roofing System due to wind damage.