Barndominiums are popular in many areas now, but weren't so common when this thread started years ago.
Today, lots of people are building residential and multi-purpose structures with steel. There are also a lot of post frame construction buildings that go up a lot like a metal building, but use large wood components to achieve some of the benefits typically found with steel (e.g. large clear-span interior spaces, exterior walls with girts).
Weld-up red iron metal buildings give you the most customization and change-on-the-fly options. Bolt-up red iron, and bolt-up thin-tubing galvanized buildings are similar to manufactured homes in that you pick a design or floorplan, the parts are prepared at a factory, and a kit is shipped to the location where the building is raised very quickly. Weld-up buildings can go up fast if the design is simple, but take a bit longer the more you approach the project as a custom work of art versus standard rectangle.
Weld-up and bolt-up metal buildings, and post frame construction buildings, typically use sheet metal for the exterior walls and roof.
There are also light-weight steel framing options to build almost exactly like traditional stick-built 2x4 and 2x6 construction, where you would not know the framing is metal versus wood once the drywall is up. These buildings don't typically "look" like metal buildings, but enjoy some of the benefits - no threat from termites or rot, etc. As wood continues to rise in price, expect this to become more common.
Regarding concrete, new construction using ICF (insulated concrete forms) is growing in popularity, where the forms are similar to hollow Lego blocks with insulation on two sides, and you pour concrete in the center once the walls are up. ICF is the best way to build modern castles, err, homes.
I did some time in Panama, and loved the cinder block homes and stucco homes, both very popular, with tin roofs. In the states, insulation is required for folks to endure winter and reduce costs with central air conditioning.
Given this is the welding section of the forum, attached is an in-progress photo for the shack I'm building to house the tractor. After the metal siding and roof is up, I'm thinking about closed cell spray foam insulation. I've been following behind a lot of armored trucks lately, waiting for stuff to fall out the back.
