When researching ADU plans in San Diego, homeowners often focus on the visible features: square footage, bedroom count, exterior style, and layout. Those details matter, but there is another detail that can be just as important: where the plan originates and where it is accepted. A plan may originate from one city or county program and be accepted somewhere else. That does not mean it is automatically usable for every property. It means homeowners need to read the plan record carefully and verify the current status with the official source. For San Diego homeowners, the San Diego pre-approved ADU plans page on ADU Plan Finder is a useful starting point because it helps compare accepted listings, providers, plan sizes, source links, permit context, and origin program information. Why origin matters The origin of a plan is the program or source catalog where the plan first appears. For example, a plan might come from a city catalog, a county standard plan program, or a provider-linked source.…