Most modular building systems offer a two step process – first build a sub-structure, then affix panels. The EXO™ Building System has an integrated steel frame built into its EXO™ Panels that can be directly fastened to others quickly and easily. This eliminates the need for an independent supporting structure and shortens the construction process to one step. Builders can complete a sealed building envelope (with windows and doors installed) within days with only a small group of trained professionals. The EXO™ Building System is a modular system, factory built and assembled on site.