If you have the land and your city allows it, an ADU is often a good idea, as long as the use case carries the math and any resale bump is treated as a bonus. The demand is real. ADUs fit multigenerational living, they can generate rent, and some buyers specifically hunt for a home that already has one. The catch is appraised value. Most neighborhoods do not have enough sales of comparable homes with and without an ADU to pin down what one adds, so a $100,000 build (illustrative figure) does not automatically show up as $100,000 of appraised value. Two questions to run: - Use value. What is the rental income or family-use benefit worth to you over the years you plan to own the home? - Resale value. Real, but fuzzy. Do not count on a dollar-for-dollar return. If the rent or the added flexibility justifies the build cost on its own, the uncertain resale upside is gravy. And confirm what your local rules allow before you draw plans, because ADU regulations and permitting vary by area and change over time.