Having an entire remodel done and they suggested adding concrete to top of spa wall to bring it up even with the deck elevation. This will be an approximately 4" tall and 7" wide addition. Should they be using some fiberglass rebar at the top or to side of the existing wall to help secure or is that even possible? I'm concerned about just having a floating piece of concrete there without any mechanical adhesion. I believe they plan on building the form and pouring without any rebar.