I was wondering what the typical size (diameter) of rebar that would be used to refinforce a concrete slab foundation? I am planning on using a concrete strip foundation in a future project. My reasoning.... In some previous work done by a builder on my property (conservatory) a foundation was called for at 300mm deep, 600mm wide without any rebar but the builder banged in some rebar. He said he'd been burned in the past with bad press from a client whose foundation failed on similar conservatory work so he said he now does this as standard. Sounds like a good idea, I will be doing this future work myself and would like to add rebar but have no idea how thick and how much etc. Is this a sensible idea or overkill?