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Understanding the different types of Accessory Dwelling Units is the first step in planning your project. In California, state law provides specific guidelines for how these units are classified and the size limits allowed.

• Detached ADU: This is a standalone structure that is physically separate from the primary residence. It is ideal for maximum privacy and is often used as a rental property or a complete guest house.
• Attached ADU: This unit shares at least one common wall with the primary house. It is often a more cost-effective option for homeowners who want to expand their existing footprint while maintaining easy access to the main home.

The size of your ADU is governed by both state minimums and local city/county maximums. Generally, the following standards apply across Los Angeles and Orange County:

• Efficiency Standard: At a minimum, an ADU must be able to accommodate an efficiency unit, which is typically around 150 to 220 square feet. It must include a kitchen and a bathroom.

• State Minimum Requirement: By law, local jurisdictions must allow at least 800 square feet for a detached ADU.
• One-Bedroom ADU: Most cities allow up to 850 square feet.
• Two+ Bedroom ADU: Most cities allow up to 1,000 square feet.
• The 1,200 Sq. Ft. Rule: Many jurisdictions in Southern California allow for a maximum of 1,200 square feet, depending on your lot size and local ordinances.
• Attached ADU Limit: An attached ADU cannot exceed 50% of the total floor area of the existing primary residence (but the city must still allow at least 800 sq. ft. regardless of this percentage).

• Height: Most detached ADUs can reach a height of 16 to 18 feet (allowing for vaulted ceilings or even two stories in certain zones).
• Setbacks: State law has reduced the required "side and rear" setbacks to just 4 feet, allowing you to maximize the usable space in your backyard.

While state laws provide a "floor" for what is allowed, every city—from Whittier to Irvine—has its own specific "flavor" of these rules. Our team specializes in navigating these local nuances to ensure you get the maximum allowable square footage for your property.

Not sure how much square footage your lot allows? Schedule a Site Feasibility Study today

A Junior Accessory Dwelling Unit, or JADU, is a smaller, more streamlined version of a standard ADU. It is a unique housing option designed to be created entirely within the existing walls of a single-family residence. JADUs are an excellent option for homeowners looking for a lower-cost conversion that provides high-yield rental potential or private living for family members.

• Maximum Size: A JADU cannot exceed 500 square feet.
• Location: It must be contained entirely within the existing primary residence or an attached garage.
• Independent Entrance: Like a full ADU, a JADU must have its own separate exterior entrance from the main home.
• Efficiency Kitchen: The unit must include a dedicated kitchen area with a sink and appliances, though it can be more compact than a full-sized kitchen.
• Shared or Private Bathroom: Unlike standard ADUs, a JADU is permitted to share a bathroom with the main residence, though many homeowners choose to install a private one to increase value and privacy.

• Cost-Effectiveness: Because JADUs utilize the existing structure of your home, they typically require significantly less construction and infrastructure work than a detached unit.
• Owner Occupancy: It is important to note that state law requires the owner to reside in either the JADU or the main home (this is a key difference from standard ADUs).
• Utility Efficiency: JADUs are not considered "new" residential utility connections, which often means lower impact fees and simplified plumbing and electrical requirements.
• "The ADU + JADU" Advantage: In many Southern California jurisdictions, homeowners are allowed to build both one detached ADU and one JADU on the same property, effectively turning a single-family home into a triplex for maximum rental income.

Converting a portion of your home into a legal JADU requires a precise understanding of fire separation, soundproofing, and building codes. At BMV Construction, we specialize in these complex interior conversions, ensuring that your new unit is not only beautiful and functional but fully compliant with all local safety standards.

Is a JADU right for your home? Contact us to find out how you can maximize your existing square footage.