Both. The material on the outside of the pictured dome is usually just a covering over the wood or steel hexagonal frame. Sometimes it's concrete originally f

Both. The material on the outside of the pictured dome is usually just a covering over the wood or steel hexagonal frame. Sometimes it's concrete originally formed with an inflatable, but that's rarer. I live in a geodesic dome home and I learned a lot about them, originally designed by Buckminster Fuller, they are inherently resilient against hurricanes, earthquakes, and all manner of environmental events. The Adobe coating on the pictured one just replaces roofing and helps seal them up. Most domes don't use that.