Like many shows, this one (although it takes a year to film) ends without a final structure in place. Due to unforeseen expenses, site issues, and the inexperience of the architects, the show ends with merely a skeleton of 2/3rds of the build and an unfinished part that is planned for the bedrooms. The whole idea of the straw and sandbag walls has to be altered because of code issues, although Kevin does use the straw-wall idea to build himself a study adjacent to his lighting-manufacturing business (which is the more interesting aspect of this episode.) The design might have been "grand," but the planning and execution were far from that. Maybe somewhere along the line this site was re-visited, as some were.