Our price and cost estimates for a turn-key, pre-designed ADU from Bay Modular ranges from $275 - $335+ per sqft. Bay Modular also offers a Solo Studio 1 which can range in cost from $235 - $350+ per square foot depending on whether or not a bathroom is included. These estimates are all inclusive, meaning that the cost of the ADU, interior finishes, labor and site work are included. These cost estimates are based on the turn-key cost estimates from Bay Modular for ADUs in their Solo Series plus elements that aren’t included such as permit costs, solar, and if necessary, craning and utility upgrades. Together, these elements can add up to $10,000 or more to the cost of an ADU project from Bay Modular. It is worth noting that buyers with exceptionally difficult building sites or individuals looking for upgraded finishes may experience costs higher than we have estimated. Below, you can find a table of our cost estimates for a finished prefab ADU from Bay Modular.