The most important cost difference between ADU vs JADU construction might catch many homeowners off guard. 

Size and requirements create substantial differences between these two dwelling unit options. Junior Accessory Dwelling Units (JADUs) provide up to 500 square feet of living space within existing structures. Accessory Dwelling Units (ADUs) can stretch to 1,200 square feet as standalone units. California’s legislation now lets property owners add both one ADU and one JADU to their property. This change opens up several possibilities for extra living space.

Our detailed look at ADUs and JADUs will help you pick the option that lines up with your property’s goals and budget. Your decision-making process will benefit from our breakdown of size limits, building requirements, costs, and regulations.

Understanding the Basics:        ADU vs JADU Defined

Anyone looking to build a secondary housing unit should know the differences between available options. ADUs and JADUs have distinct features that set them apart.

What is an Accessory Dwelling Unit (ADU)?

An Accessory Dwelling Unit serves as a secondary residential unit on the same lot as a primary home. People often call them granny flats, in-law suites, or backyard cottages. These units remain tied to the main house and cannot be sold separately. Each unit stands as a complete living space with its own kitchen, bathroom, sleeping area, and separate entrance.

ADUs come in three main types:

• Detached ADUs: Standalone structures completely separate from the primary residence, offering maximum privacy
• Attached ADUs: Extensions connected to the main house but with their own entrance
• Conversion ADUs: Spaces like garages or basements turned into independent living quarters

Local regulations allow ADUs to range in size from 600 to 1,200 square feet. This size makes them perfect for couples, small families, or seniors.

What is a Junior Accessory Dwelling Unit (JADU)?

Junior Accessory Dwelling Units fit within existing single-family home walls and measure up to 500 square feet. These spaces merge with the home’s structure and make smart use of existing space.

Key JADU requirements include:

• Must be contained entirely within a single-family residence
• Requires a separate entrance from the main house
• Needs an efficiency kitchen with simple cooking facilities
• May share a bathroom with the primary dwelling or have its own

JADUs must stay connected to the main house and fit within the existing structure. The rules also state that someone must own and live in either the JADU or the main house, as outlined in the owner-occupancy requirements.

Key similarities between ADUs and JADUs

ADUs and JADUs share several important features:

These living spaces help solve housing needs on existing properties. Both units stay connected to the main house legally and need similar approval processes. They can also generate rental income, though JADUs might bring in less money because of their smaller size.

ADUs and JADUs excel at bringing families closer while giving everyone their space. Many families choose these units so elderly parents or adult children can live independently yet stay close by.

Size and Location Requirements: The Physical Differences

“ADUs can generally reach a size of up to 1,200 square feet or 50% of the existing living area, while JADUs have a capped maximum size of 500 square feet.” — Aspire Los Angeles, ADU construction company

The most noticeable differences between an ADU and JADU are their size and where you can put them. These requirements affect how each unit works with your property’s layout.

ADU size limitations and placement options

ADUs need at least 150 square feet of living space to be functional. They can be much bigger, with detached units going up to 1,200 square feet. Attached ADUs can be 1,200 square feet or half the size of your main house, whichever is smaller.

You have plenty of options to place your ADU. You can build it as:

• A separate building from your main house
• An addition attached to your existing home
• A converted space from your garage or basement

New ADUs need to be at least 4 feet away from your side and rear property lines. The front setbacks match what’s required for your main house.

JADU size restrictions and where they can build them

JADUs come with tighter rules. They must fit entirely within your existing or planned single-family home or attached garage. JADUs can be up to 500 square feet, but no smaller than 150 square feet.

A JADU needs its own outside entrance, separate from the main house. It must also connect to your main house from the inside. This setup falls somewhere between having a roommate and a separate unit.

How these differences affect your property layout

Each type of unit changes how your property works in its own way. ADUs can be separate buildings, which gives everyone more privacy. This makes them great for multi-generational families or rental income.

JADUs use space you already have instead of adding to your home’s footprint. They “do not put additional stress on utility services or infrastructure because they simply repurpose spare bedrooms that do not expand the home’s planned occupancy”.

California law now lets eligible properties have both an ADU and a JADU at the same time. This means you could have three separate living spaces on one residential lot.

Feature Comparison: Kitchens, Bathrooms, and Utilities

The size is not the only thing that sets ADUs and JADUs apart. Their interior amenities and utility setups create big differences that affect how people live in them and what it takes to build them.

ADU amenity requirements

ADUs must include detailed amenities as independent living spaces. They need a full kitchen with a sink, refrigerator (at least 10 cubic feet), and either a stove, range top, or oven. Each ADU needs its own private bathroom.

This setup creates a completely independent living space.   These features make ADUs work as complete housing units with everything needed for daily life – kitchen, bathroom, sleeping area, and living space. 

The setup works great for couples, small families, friends, young people, and seniors.

JADU efficiency kitchen and bathroom options

JADUs work differently with simpler amenities. They must have an efficiency kitchen that includes:

• A sink
• A cooking facility with small, plug-in appliances
• A food preparation counter
• Storage cabinets

JADUs can’t have permanent kitchen features like built-in stovetops or ovens. They’re flexible with bathroom arrangements – they can have their own bathroom or share one with the main house.

This setup puts JADUs somewhere between having a roommate and a separate tenant. The connection to the main house creates a unique living space that you can easily make private or open to the main living area.

Utility connections and independence levels

Utility setups show how differently these units integrate with the main house. ADUs usually need their own utility connections, especially when they’re detached. They require separate water, sewer, gas, and electrical hookups.

JADUs typically share the main house’s central systems, including electricity and water. You can’t charge JADUs separate connection fees for water, sewer, or power services because they’re not considered separate dwelling units.

This shared system makes JADUs cheaper to build while letting them work independently. It simplifies construction and cuts down on development costs.

Cost and Timeline Analysis: What to Expect

Money often makes the final call between an ADU and JADU. You’ll make better choices that match your budget once you know what each option costs.

Permit fees and regulatory expenses

Permit fees take up much of your budget for both units. JADUs have lower permit fees at about $1,454 in some areas. ADUs cost more at roughly $2,832.

California now waives fees for smaller units. ADUs under 750 square feet don’t pay impact fees. JADUs usually skip development impact fees altogether. Larger ADUs might face fees up to $20,000.

Note that both choices need building, electrical, plumbing, and zoning permits. On top of that, you’ll need to plan for ongoing costs like higher property taxes, insurance premiums, and utility bills, whatever option you pick.

Conclusion

Don’t let indecision delay your property’s potential!

As you weigh the options between an Accessory Dwelling Unit (ADU) and a Junior Accessory Dwelling Unit (JADU), remember that each path offers unique advantages tailored to different needs and budgets.​

An ADU provides a fully independent living space, ideal for generating rental income or accommodating family members, with construction costs typically ranging from $200,000 to $400,000. ​

On the other hand, a JADU is a more budget-friendly option, costing between $50,000 and $90,000, as it utilizes existing space within your home and may share facilities. ​

California law permits the construction of both an ADU and a JADU on eligible properties, potentially transforming your single lot into three separate living spaces. ​

Before embarking on this journey, take the time to assess your long-term goals, financial capacity, and property constraints. Consulting with experienced contractors and researching local regulations will equip you with the knowledge to make an informed decision. By aligning your choice with your vision and resources, you’ll enhance your property’s value and versatility for years to come.