Determine what additions will be made to the manufactured home by hiring a contractor to plan the new addition. Ask the contractor to draw up a blueprint of the home with the addition. Agree on the costs for the addition with the contractor and set up a plan for payment based on work completion.
Contact local or state inspectors to determine which authority must supervise and approve the building of the new addition. Some jurisdictions conduct the inspections themselves; others permit a licensed, professional engineer to approve the addition.
Verify with the U.S. Department of Housing and Urban Development -- HUD -- that the addition meets HUD manufactured home safety standards. The standards are available on HUD's website, hud.gov.
Build the addition after obtaining the requisite state or local permits and complying with HUD safety standards. The contractor must comply with inspection requirements at every phase of the building process. Verify whether a new certificate of occupancy must be issued after completion of the addition.