It has a corrugated pattern so I’m hoping someone recognizes this roof covering type. It appeared to be a rubber coating on what appeared to be metal and had a little give when walking. I’m now kicking myself for not pulling out a magnet.
My feeling is aluminum with a rubberized coating but I want to be positive or I’ll have to state “uncertain” (with my feelings noted) in the report.
“The roof features a reflective rubber-like surface coating. The condition and type of roofing material beneath this coating cannot be determined at this time due to the limitations of this visual inspection.”
I seen those roofs on modular class room units at the school board where I live. I believe that it is a membrane that is coated with tar. I have that impression because you said that when you walk on it there some depression. I had to walk on a roof like this one and if the conditions are right your feet can press into the tar and cut the surface that would leave an impression of your shoes.