From the HTA
Also keep in mind that if you're load sticks out 1.5 metres or more, you need to place a red flag or light on it.(2) No person shall operate or permit to be operated upon a highway a motor vehicle that carries a load or draws a vehicle that carries a load unless the load is loaded, bound, secured, contained or covered so that no portion of the load may become dislodged or fall, leak, spill or blow from the vehicle. 2002, c. 18, Sched. P, s. 26.