Two items of my extended learning about the Concrete encased electrode.
If the rebar is used only in the walls of the foundation and not the footer it is NOT suitable as the Ufer ground.
Caution must be taken where the rebar comes out of the top of a wall that has a treated lumber sill plate. The newer treated lumber is extremely corrosive to metal. Contractors are having to use either stainless steel or an extra thick coating of galvanize on fasteners with the newer lumber, when building decks etc.
This is all because the water lines are becoming non-metalic. Even wells are PVC with metal only at the top.
Next big head ache is the CSST gas lines.