How is the flashing size determined?
The size of the flashing is determined by the OD (outside diameter) of the pipe penetrating the roof or sidewall of home or building. Never try to slide a smaller flashing collar over a larger pipe because it will cause fatigue failure in the collar. Never install a larger collar over a smaller pipe and try to use sealant to fill the void. Any sizing miscalculations will lead to leaks within the home or building.
