Pick the product before the floor plan. A junior ADU and a full ADU are different California dwelling types. The City of San Diego lists both on its companion and junior unit program page. Both need a building permit. Neither is a shortcut around residential building, health and safety, fire, and energy standards.
What a junior ADU is
A JADU must be built within the walls of a proposed or existing single-family residence. For that rule, an attached garage is part of the house. A detached garage is not. Converting a detached garage is the full ADU path.
The City of San Diego lists JADUs from 150 to 500 square feet. The unit needs its own exterior entrance and an efficiency kitchen: a cooking facility with appliances, plus a reasonably sized food-preparation counter and storage cabinets. A private bathroom is not required. Sharing sanitation with the main house is allowed.
A recorded deed restriction must run with the land and bar selling the JADU separately from the house. Owner occupancy is not a blanket yes or no. If the JADU shares sanitation with the primary structure, the owner must live in either the house or the JADU. If the JADU has separate sanitation, that occupancy rule does not apply. Government agencies, land trusts, and housing organizations have a waiver. The longer walk-through is the JADU deed and occupancy guide.
What a full ADU is
A full ADU is a dwelling with complete independent living facilities. It can be created in an attached or detached garage. The City of San Diego lists ADUs from 150 to 1,200 square feet. Local lot rules still shape what fits.
A local agency cannot impose an owner-occupancy requirement on a standard ADU. The city can still require rentals of 30 days or longer. Do not treat an ADU as a short-term rental plan unless you have confirmed the current local rule in writing.
State law also bars most replacement-parking requirements when a garage becomes an ADU. The City of San Diego still lists a Beach Impact area exception outside transit priority areas. Confirm the parcel on the City maps, not by neighborhood name. Pacific Beach parking is covered separately in the Pacific Beach parking guide.
Which garage usually takes which path
An attached one-car garage often fits the JADU envelope because of the 500 square foot cap and the attached-structure rule. It can still become a compact full ADU if the plans provide independent living facilities and the city accepts the size.
A two-car attached garage can go either way. Choose JADU when you want the attached-home product, a possible shared bath, and the deed restriction. Choose a full ADU when you want a complete independent unit, including a full kitchen and bath.
A detached garage cannot be a JADU. Plan it as a full ADU, including the plumbing run from the main house.
Cost, without invented rent
Published market bands on this site, not a quote from Garage Convert SD: a junior ADU conversion including permits is listed at $50,000-$90,000. A full ADU conversion including permits and all trades is listed at $75,000-$150,000. Those ranges live on the junior ADU and full ADU service pages and the cost hub. The licensed pro’s written proposal is the price.
Impact fees are a separate legal line. State law bars impact fees on a JADU of 500 square feet or less of interior livable space, and on an ADU of 750 square feet or less. That exemption does not cover plan-check, permit, connection, or school fees. This site does not publish rental-income figures.
Questions that change the drawing set
Can the existing attached garage stay inside 500 square feet and still work as daily living space? If yes, JADU is on the table.
Is the garage detached? Then skip JADU.
Do you want a private bathroom inside the unit? That choice changes both comfort and the JADU occupancy rule.
Will someone live in the main house or in the JADU if sanitation is shared? If neither, the JADU path may not fit.
Garage Convert SD matches homeowners with licensed independent local professionals. The homeowner contracts with and pays that professional directly. Call (858) 400-4935 or use contact.
Can a JADU and an ADU both sit on the same lot?
Ask the building department that will stamp the plans. Lot rules differ by city and by County land. This page does not invent a countywide pairing.
Is a junior ADU always cheaper than a full ADU?
The JADU scope is often smaller. Adding a bathroom, a long plumbing run, or a heavy structural repair can close that gap. Compare written scopes, not product names.
Do JADUs require a separate utility meter?
Confirm meter and account rules with the utility that serves the address. State law on connection fees and capacity charges is a different question from whether a second meter is installed.