In Plain Language

No double Y, double TY, double T, or double waste fitting can be installed in a nominally horizontal soil or waste pipe, restricting fitting geometries that could cause cross-flow problems between two drain lines.

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.