A Certificate of Fitness holder must be present to perform fire watch during hot work operations at: 1) construction sites, 2) rooftop operations where torch-applied roof systems are in operation, and 3) in any building or structure where a torch operation is conducted. A certificate holder is also required at sites when construction, alteration or demolition exceeds 10,000 square feet when fronting one street, 20,000 square feet when fronting two streets, or whenever the building exceeds 75 feet in height.