Today "prefab" is the buzzword of modern architectural design. Prefab homes or Modular Homes are often indistinguishable from a custom built house. These homes embody minimalist modern design principles like open floor plans and large windows. Prefab is nearly synonymous with green building since manufacturing and construction efficiencies reduce waster far beyond a typical onsite construction. Prefab homes are usually less expensive than site built, since costs are laid out upfront, there is less chance of runaway expenses.