The modular home itself is only one part of the project. Homeowners should ask for a written scope that clearly separates factory work from on-site work.
Common items to confirm in writing are foundation type, delivery, crane set day, finish work after the set, utility hookups, driveways, grading, septic or sewer, well or water service, permits, and inspections. Foundation choices often include slab, crawlspace, or basement, depending on the site and local rules.
Some builders handle more of the project than others. Some coordinate almost everything, while others focus on the home package and leave more site work to local trades. Always verify the builder's license and insurance yourself, and confirm price, scope, and timeline in writing before you sign.