Adding an ADU? Know the real cost first.

Most ADU costs you'll see online stop at the build price per square foot. The real number also includes design and engineering, plan check and permit fees, school fees, and utility hookups, and together those add tens of thousands before a single wall goes up. This free guide breaks down every cost for five build options, from a garage conversion to a 1,200 sq ft detached unit, using real numbers from a local San Diego ADU builder.