Purchased 2 x 2 x 1/8″ 19′ long 6063 aluminum channel and installed on 2′ centers. $46 each. Attached them with 1/4″ aluminum rivets every 12″.
The walls will be insulated with pink rigid insulation, 1/2″ plywood and then FRP in all areas but the 6′ hood. Behind the hot appliances will be stainless steel with no plywood and no insulation.
Ceiling will be fiberglass insulation with FRP.
Next project…frame the new window, 8’x3′, and install the studs on the service side.
Removed the ceiling. I thought it smelled off when pulling it down, found lots of mouse droppings. And to think it used to be a bread truck…..