The Ontario Building Code | Connection of Roof Drain to Leader
7.3.3.7. Connection of Roof Drain to Leader
(1) Every roof drain shall be securely connected to a leader and provision shall be made for expansion.
In Plain Language
Every roof drain must be securely connected to its leader (the vertical pipe carrying water down), so the connection can't work loose and cause water damage inside the building.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.