Differences Between ADU and JADU Permits

When planning an additional living space, many homeowners wonder: What’s the difference between an ADU and a JADU permit?

Understanding the distinctions — and preparing your project with a preapproved ADU plan, a detailed ADU blue print, or permit ready ADU plans — helps set clear expectations for approvals, design, and costs.

What Is an ADU?

An Accessory Dwelling Unit (ADU) is a fully independent living unit. It can be:

• Detached from the primary home

• Attached to the primary home

• Converted from an existing structure (like a garage)

Typical features of an ADU include:

• Full kitchen

• Bathroom

• Separate utilities (optional)

• Private entrance

ADUs can be up to 1,200 square feet, depending on local zoning.

What Is a JADU?

A Junior Accessory Dwelling Unit (JADU) is:

• Created within an existing home or attached garage

• Limited to 500 square feet

• Allowed to share a bathroom with the main home

• Required to have an efficiency kitchen

• Required to record an owner-occupancy deed restriction

JADUs are faster and cheaper to permit, but more limited in size and flexibility.

Key Differences at a Glance

Feature	ADU	JADU
Maximum Size	Up to 1,200 sq ft	500 sq ft max
Separate Kitchen	Full kitchen required	Efficiency kitchen required
Bathroom	Private bathroom required	May share bathroom with main home
Construction Type	Detached, attached, or conversion	Interior conversion only
Owner Occupancy	Not required (some exceptions)	Required (deed restriction recorded)
Utility Meters	Separate meters optional	Typically share utilities with main home

Permit Process Differences

• ADUs:Require a full permit application, including site plans, ADU blue prints, structural details, and Title 24 energy compliance documents.

• JADUs:Have a simpler, faster review — but require deed restrictions and owner-occupancy confirmations in addition to site plans and energy documents.

Using permit ready ADU plans or preapproved ADU plans speeds up the process for both types of projects.

Timeline Differences

• JADU Permits:Typically approved within 4–8 weeks with complete documents.

• ADU Permits:Typically take 2–6 months depending on complexity and city workload.

Choosing a preapproved ADU plan aligned with local standards helps cut timelines dramatically.

Cost Differences

• JADU Permit Costs: Lower — fewer impact fees, smaller utility upgrades.

• ADU Permit Costs: Higher — full fees apply, plus potential utility connection charges for detached units.

Real-World Example

A homeowner in Fremont added both a detached ADU and an interior JADU.Using a permit ready ADU plan for the ADU and a simple ADU blue print for the JADU, both permits were approved within four months — allowing construction to proceed on schedule.

Common Mistakes to Avoid

• Designing a JADU over 500 square feet (disqualifies the project)

• Forgetting owner occupancy requirements for JADUs

• Not preparing separate Title 24 energy documents for each unit

• Misunderstanding bathroom sharing rules

Final Thoughts

Understanding the differences between ADU and JADU permits helps homeowners plan projects more strategically, saving time and money. At ADUnest, we help clients prepare detailed ADU blueprints, select the right preapproved ADU plans, and submit permit ready ADU plans that meet all city requirements for both ADUs and JADUs.If you have any questions about which type of permit fits your project, leave a comment below — the ADUnest team is ready to assist you!