These joists will help lock in and support the panel walls and provide a platform for the countertop. They come in 40" and 28" to fit between the 48" and 32" panels. They can be screwed into the top of a precast panel wherever deemed necessary. It is common to try and have them every 18" - 24" depending on the layout and where the appliances are placed.
Joists may have to be custom cut for the back of the grill opening.