Most typical flat roofs in south florida should last anywhere from 10 to 20 yrs. Flat built up roofs are highly wind resistant but very susceptible to leaks at the seams from buckles or wrinkles in the top membrane as a result of poor workmanship.One way to extend the life a typical residential flat roof is by applying a 5 to 10 yr elastomeric coating. The coating preserve to roof membrane from sun exposure and harsh weather conditions such as rain and heavy winds. The white finish of the roof will also give you extra R-value helping you save money in calling energy bills.
color of roof - a dark roof absorbs more heat which shortens the life span.
Angle of roof slope - higher pitch roofs tend to last longer
Orientation of roof surface - a roof slope facing south will get more sunlight and have a shorter life.
Multiple-layer roof- a roof installed over an existing roof will have a shorter life.
Quality of roof material- “economy” roof materials have a shorter life
Installation - Sloppy or improper installation shortens roof life.
Attic ventilation - an unventilated or poorly ventilated attic reduces roof lifespan