In every attic i’ve ever seen (except for something low with a 6/12  pitch or so)
the support framing confuses me, why are there vertical support bracing running everywhere when they’re not structurally needed?

Just as an example, we have 2×8 syp#2 rafters w/ a 12/12 rise, supporting light roofing(20#live load) with a 12′ span spaced 16″ O.C. Plus collar ties and they still have these vertical bracing members all over the place, i honestly don’t see how a water heater is getting though that, much less an A/C unit.

So someone please shed some light on this for me, is this just simply misinterpretation between the building plans and the framers? or maybe “eh, just a little extra support”? Because even with a 40lb live load on this roof you wouldn’t need additional support.

Thanks for your input everyone