Because builders have found that it is easier to control costs and maintain consistent construction quality by using factory-built components. The factory construction process is what allows manufactured homes to offer the winning combination of quality construction at a price you can afford. In a factory environment, all aspects of the construction process are controlled. The weather doesn't interfere or cause costly delays. There are no independent, uncontrolled, and expensive subcontractors to deal with.
All workers are on the same team and efficiently supervised.
Inventory is better controlled and materials are securely protected from theft. Interior features and appliances are purchased in volume for additional savings. These efficiencies are then passed on to you, the homebuyer. Also, the manufactured home industry continually introduces new, innovative and cost-saving building techniques that enable the quality, safety and durability of its homes to steadily improve. During the last two decades, manufactured homes have become a practical housing option for people of all income levels, all occupations, and all family sizes and lifestyles.