Junior ADU (JADU)
Junior ADU: the smallest, cheapest legal ADU in California.
A Junior ADU (JADU) is capped at 500 sq ft and must be carved out of the existing primary home or an attached garage. It's the most affordable legal ADU in California — $30K–$100K typical in 2026 (Redshed 2026) — but it comes with specific constraints, especially around owner-occupancy and shared bathrooms.
What it is
A small secondary unit (≤500 sq ft) inside the primary home or attached garage, with its own exterior entrance, an efficiency kitchen, and either a private or shared bathroom. Defined and regulated by California Government Code §65852.22.
- Cost range
- $30K–$100K (San Jose, Redshed 2026); $50K–$100K range nationally for comparable scope
- Per sq ft
- $100–$300 per sq ft depending on scope and bathroom configuration
- Size cap
- 500 sq ft hard cap — no expansion allowance
- Timeline
- 4–7 months total project including permits (Redshed 2026)
Pros
- Lowest absolute cost of any legal ADU type
- Fastest to permit and build — uses existing space
- Efficiency kitchen requirement is simpler than a full ADU kitchen
- Can be combined with one standard ADU on the same lot — California allows both
Cons
- 500 sq ft cap — no exceptions
- Must be inside primary home or attached garage; detached not allowed
- Owner-occupancy required when bathroom is shared with primary home
- Garage-to-JADU conversions require parking replacement (unlike standard ADU garage conversions)
- Deed restriction recorded against the property — JADU cannot be sold separately
- Lower rent than full ADU — typically $1,400–$2,200/mo in CA metros
Rules and requirements
| Maximum size | 500 sq ft (hard cap) |
| Location | Inside existing primary home OR attached garage only — never detached |
| Kitchen | Efficiency kitchen — sink, counter, cooking appliance, storage |
| Bathroom | Private OR shared with main home |
| Owner-occupancy | Required when bathroom is shared (CA Gov Code §65852.22) |
| Parking | Replacement required for attached-garage JADU conversions |
| Deed restriction | Required — cannot be sold separately from primary home |
Best for
- Budget under $100K and you need a legal, rentable unit
- You'll always live on the property — owner-occupancy isn't a constraint
- Housing a family member rather than a market tenant
- Maximizing rental income via the JADU+detached-ADU combination on the same lot
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FAQ
- Can I rent out a JADU?
- Yes — JADUs are legal rental units. If the bathroom is shared with the primary home, the owner must live on the property (in either the JADU or the main home). With a private bathroom, the rental flexibility is broader; confirm current local rules.
- What's an 'efficiency kitchen' for a JADU?
- Counter, storage cabinets, sink, and a cooking appliance. A 240V induction cooktop, a countertop convection oven, and a compact sink satisfy California's JADU kitchen requirements. Full gas range is not required (Redshed 2026).
- Can I have both a JADU and a standard ADU on my lot?
- Yes — California law allows one standard ADU plus one JADU on most single-family lots. A common strategy: convert the attached garage to a JADU and build a new detached ADU in the backyard, producing three legal residences on the property. Combined Bay Area rental income on the two rentals can reach $4,500–$5,500/month (Redshed 2026).
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