Bending Class of Reinforced Steel Beams

Hello, I am working on reinforcing steel beams for new, higher loads. For steel beams, the bending class determines if you use the plastic section modulus (Z) or the elastic section modulus (S). How can I figure out what the bending class of my new reinforced beam is? I've read through the steel code (S16, I'm in Canada) and all I see is a table for ratios of b/t and h/w but that doesn't really apply when the section is reinforced. I'm using two methods which are adding rods either side of the web just inside the flanges, and adding a WT to the bottom of the beam.

Thanks