Junior ADU
Want to add livable space without major construction? A Junior ADU (JADU) is a compact, affordable solution that's perfect for guests, renters, or family - and easier to permit than you might expect.
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Junior ADUs are compact living spaces created from existing interior areas, often with shared bathrooms and small kitchenettes. Limited to 500 sq. ft. and located within the main home, they offer an affordable way to house families or earn rental income.
Benefits
Why Build a Junior ADU?
Lower Costs
Save significantly on construction and permits compared to building a full ADU.
Faster Build Time
Quick to design and complete - most junior ADU California projects take weeks, not months.
Multi-gen Living
Perfect for aging parents, college kids, or extended family staying close.
Boosts Property Value
Adds functional living space that increases home appeal and resale potential.
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Junior ADU Requirements in California
Size Limit
Must be no larger than 500 sq. ft. and located within the main home.
Kitchenette Required
Needs a basic kitchenette with a sink, small fridge, and cooking appliance.
Bathroom Options
Can share a bathroom with the main house or have a separate one.
Private Entrance
Must include a separate exterior entrance from the main house.
prices
What Affects the Junior ADU Cost
Existing layout of your home
Whether plumbing and electrical need updates
Custom design choices and finishes
Permit costs in your area
Cost Estimate
A Junior ADU in Los-Angeles or San Diego can cost anywhere from $25,000 to $80,000. Compared to full ADUs that often range above $150,000, junior ADUs are budget-friendly.
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Junior ADU Floor Plans & Smart Layout Ideas
Legacy Urban Units
Legacy Urban Units
A bright and airy 400 sq ft unit for an aging parent, complete with wide doorways and no steps
Legacy Urban Units 2
Legacy Urban Units 2
A bright and airy 400 sq ft unit for an aging parent, complete with wide doorways and no steps
FAQ
Quick Answers About Junior ADUs
Can I build a Junior ADU if I already have an ADU?
Yes, California law allows both an ADU and a JADU on most single-family lots.
Do Junior ADUs require fire sprinklers?
Not if the main house doesn’t already have them.
Can I rent out my Junior ADU?
Yes, long-term rentals are allowed, but short-term rentals (like Airbnb) may be restricted.
Do I need an architect for my junior ADU?
Not always. For simple conversions, we can design and draft in-house.
Ready to Unlock More Space?
Whether you’re just curious or ready to build, we’re here to help you get started the right way.
More information
ADU Scale helps homeowners across California create beautiful, compliant Junior ADUs with ease.
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