Sexual Reproduction; each parent passes down half of their genes to the offspring.
Climate, especially temperature and rainfall patterns
Microclimates on the roof top
Strength of the supporting structure
Size, slope, height and directional orientation of the roof
Type of underlying waterproofing
Drainage elements, such as drains, scuppers and drainage conduits
Accessibility and intended use
Visibility, fit with architecture, and owner’s aesthetic preferences
Fit with other ‘green’ systems, such as solar panels
Materials and labor costs
Lack predators and other natural controls
Urine culture
It literally says he peed in the water