Our price and cost estimates for a prefab ADU from Modal range from $272 - $337+ per square foot. These estimates are all inclusive, meaning that the cost of the home, labor and site work are included. This cost estimate is based on the module cost of a prefab ADU from Modal ($89,000 - $129,000), plus the cost of shipping, permitting, and other on-site work. The cost of land and any home upgrades are not included in this estimate. It is worth noting that Modal ships their ADUs 100% completed, leaving very little on-site work to be done. Below, you can find a table of our cost estimates for a finished house from Modal.