Garage conversions are the cheapest way to build an ADU—and offer the greatest return on your investment. While a new 500SF stand-alone unit in Southern California can run $150,000- $160,000 or more, a 400SF garage conversion can run around $95,000-$120,000.
Is it worth it? When you factor in the value a 400SF ADU adds to your home, and the income you’ll get if you rent it out, it’s hard to find another investment that comes close to creating the value and return.
ADUs usually take between nine and fourteen months to complete, including the planning phase. This starts from the first talks with your designer to the completion of the habitable unit. Garage conversions can be much faster, typically around six to seven months. If your garage is in excellent condition, you may not need to pour a foundation, frame the ADU, or replace the roof, and that can save time.
