I live in Dallas TX, zone 3A.
I am in the planning stage of a steel building. The building will be ~2000 sqr feet & 16′ walls. I plan to section off one corner of the building to be an office space but plan to cool the entire building, 2 zones. If orientation matters the large doors will face almost directly north, with a west wall that will get direct late day sun during the heat of the summer.

The standard wall construction used by the builder I am working with is constructed like this. From the outside in.

-Steel sheeting

-insulation that is a radiant barrier & fiberglass batting surrounded by vinyl wrap.

-1″x1″ horizontal steel tubing, 4′ spacing.

-4″x4″ steel studs, 4′ spacing.

The roof is the same steel sheeting and insulation over steel trusses.

This seems suspect to me having the radiant barrier between the insulation and vinyl, and the insulation being compressed between the outside sheeting and the steel cross pieces.

I’ve asked the contractor if they have an option to use closed cell foam in place of the suggested insulation and they do.

Finally my questions are.

Since I have the opportunity to do it right the first time, how should I ask the for the walls and roof to be constructed?

I feel that I should go with the foam option and not the standard batting proposed. At some later point in time I will have to cover the foam for aesthetic looks, what should I plan to cover the foam with?

Should a radiant barrier be part of the equation?

Thanks in advance.