Anyone may design the home, other than for homes in a floodplain. The general contractor must be licensed in the state of Wisconsin (note that state UDC contractor certification checks for general liability insurance only-it does not guarantee quality of work). The plumbing work must be supervised by a master plumber and installed by licensed plumbers-homeowners may not do their own plumbing work-there are no exceptions. Any and all contractors that are used must be licensed in the state of Wisconsin. After a dwelling is occupied, homeowners may install additional plumbing themselves. All heating contractors must be state registered-owners working on their own property are exempted. Essentially, homeowners may do any of the work themselves except for the plumbing. Essentially, homeowners may do any of the work themselves except for the plumbing and electric. The electric must be done by a Wisconsin Master Electrician.