Technical Booklet N Drainage·Page 16·2.13(c)

Ventilation stack termination - connection to discharge stack

The upper end of a ventilation stack may connect to a ventilated discharge stack above the spillover level of the highest appliance served.

The upper end of a ventilation stack should connect to a ventilated discharge stack above the "spillover" level of the highest appliance served.

Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/Technical Booklet N - Drainage.pdf