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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examples

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
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FAQ

Quick Answers About Junior ADUs

Ask Anything
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.
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More information

ADU Scale helps homeowners across California create beautiful, compliant Junior ADUs with ease.
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Junior ADUs in San Diego, Los Angeles and other parts of California are gaining popularity due to updated state laws making it easier to build them. Whether you're converting existing space into a JADU or looking into prefab junior ADU options, we guide you every step of the way.
Our 4-Step Process:
Free Feasibility Check - We assess your home’s JADU potential.
Custom Design & Planning - Smart layouts made to fit your home.
Permit Management - We handle all the red tape.
Ready-to-Build Support - You get clear plans and a constructed Junior ADU.
Many homeowners use JADUs to house college-age kids, rent to local workers, or simply add flexibility to their living space. It’s one of the smartest affordable housing options available today.
At ADU Scale, we make the process smooth, fast, and reliable. We know the JADU requirements inside out. Each city has its variations - junior ADU Los Angeles rules might differ slightly from junior ADU San Diego regulations - but the basics remain the same. We handle all JADU permitting processes, zoning checks, and know how to get a permit for a junior ADU smoothly.
You’ll also get design help that blends smart room conversion ideas with real-world functionality. Curious what your home can fit? Just get in touch with us!