There are projects that you will have to have a contractor for when you are doing a modular home remodel. Things like HVAC and electrical need to be done by a licensed company or individual. There are permits and building codes that must be followed. If you do not follow these codes and get the necessary permits, you could find yourself in trouble with the local city or county government. They could even make you tear out the work and then have it redone by a licensed professional.