Attached vs. Detached ADU
Understanding the differences between attached and detached ADUs
Accessory Dwelling Units (ADUs) are a fantastic way to add extra living space, enhance property value, and offer flexible solutions for homeowners in Los Angeles. Whether you are looking to generate rental income, create a space for family members, or diversify your property, choosing the right type of ADU is crucial for meeting your goals. ADUs can be broadly categorized based on their connection to the main residence and the method of construction—whether you’re building from scratch or converting an existing structure. Below, we explore the different types of ADUs in detail, including their advantages, disadvantages, and what factors to consider in making the best choice for your property.
Types of ADUs
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Attached ADUs: An attached ADU is connected directly to the primary residence, sharing at least one common wall. It can be an addition to the existing home or involve converting existing spaces like basements or garages into a functional living area. These units are ideal for homeowners with space constraints but still want to expand their living quarters.
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Detached ADUs: Unlike attached ADUs, detached ADUs are completely separate from the main residence. They are standalone units that offer greater independence for occupants. Detached ADUs provide more design flexibility, enabling homeowners to tailor the unit to their specific needs without being constrained by the layout of the main home.
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Conversion ADUs: Conversion ADUs involve transforming existing structures—either attached or detached—into fully functional living spaces. Garages, basements, attics, or even sheds can be converted into ADUs, making this a cost-effective option for homeowners who want to maximize the use of space they already have.
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New Construction ADUs: These ADUs are built entirely from scratch, either attached to the primary residence or as a separate detached unit. New construction ADUs offer the highest level of design flexibility, allowing homeowners to create a custom space tailored to their exact specifications. Whether you’re adding on to your existing home or building an entirely new structure, new construction ADUs provide a blank canvas for creating your dream space.
Choosing the right type of ADU will greatly impact its design, functionality, privacy, cost, and the value it adds to your property. Understanding these distinctions is key to making the right decision for your needs and lifestyle.
Attached ADU: Maximize Space by Connecting to the Main Residence
Attached ADUs are connected to the main home, making them a part of the existing structure. Whether by adding space vertically—like building above a garage—or horizontally by extending the home, attached ADUs expand the footprint of the primary residence without creating a fully independent structure.
Pros of Attached ADUs
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Ideal for Small Lots: If your lot is small or space is limited, an attached ADU can make the most of the available land. This is especially helpful in densely populated urban areas where lot space is at a premium.
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Cost-Effective: Since attached ADUs can share utilities like water, electricity, and HVAC with the main home, they are often cheaper to build. Converting existing space, such as a garage or basement, can also reduce construction costs.
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Easier Permitting: Because attached ADUs often involve less new construction, they may face fewer regulatory hurdles, particularly in areas with strict zoning or construction laws.
Cons of Attached ADUs:
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Unpredictable Costs: Sharing a wall with the main home means less privacy for both the primary residents and the ADU occupants. This setup may not be ideal for renters or family members seeking independence.
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Higher Costs for Structural Modifications: Building above a garage or expanding a home can require additional structural reinforcements, raising costs.
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Design Limitations: Attached ADUs typically need to match the main home’s design, limiting creativity and customization. Some cities also cap the size of attached ADUs at 50% of the main house’s square footage, with state law guaranteeing a minimum of 850 sq. ft. for one-bedroom ADUs and 1,000 sq. ft. for two-bedroom ADUs.
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Reduced Privacy: Sharing a wall with the main home can reduce privacy for both the ADU occupants and the primary residents.
Detached ADUs: Independent Living Space with Maximum Flexibility
Detached ADUs are fully independent structures separate from the main home. These units function like mini homes, complete with their own utilities, entrances, and often their own distinct design. Detached ADUs are perfect for homeowners looking for privacy, rental opportunities, or guest accommodations without affecting the primary residence.
Pros of Detached ADUs:
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More Privacy: Detached ADUs offer complete separation from the main house, making them ideal for long-term renters or family members who want more independence. This physical separation reduces noise transfer and creates distinct living spaces.
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Design Flexibility: Detached units offer greater freedom in design and layout, as they don’t need to blend with the main home. You can opt for different architectural styles and layouts to suit your personal taste or the needs of potential tenants.
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Predictable Costs: Since a detached ADU is a standalone structure, there are fewer surprises during construction. This makes budgeting and planning more straightforward.
Cons of Detached ADUs:
Requires More Space: Detached ADUs take up more room, so they’re not feasible for smaller lots. You’ll also need to meet setback requirements, which can further reduce available space.
Higher Construction Costs: Detached units often require separate utility hookups and may have stricter permitting requirements, increasing costs. In some cases, solar installation is required, adding another layer of expense.
More Complex Permitting: Detached ADUs face additional scrutiny in some jurisdictions, making the permitting process more time-consuming.
Conversion ADUs: A Smart Way to Repurpose Existing Structures
Conversion ADUs involve transforming an existing space—such as a garage, attic, or basement—into a livable ADU. This is one of the most cost-effective ways to create an ADU, as the structure already exists and the primary focus is on interior changes.
Pros of Conversion ADUs:
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Cost Savings: Since you’re repurposing existing space, conversion ADUs are often less expensive than building from scratch.
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Preserves Outdoor Space: By utilizing existing structures, conversion ADUs help maintain outdoor areas that would otherwise be taken up by new construction.
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Less Disruptive: Conversion projects are typically faster and cause less disruption to the main residence compared to new construction.
Cons of Conversion ADUs:
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Limited Space: Depending on the size of the structure you’re converting, space may be limited, impacting the functionality of the ADU.
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Potential Challenges: Converting older structures can present challenges, such as outdated electrical systems or the need for new plumbing, which can add to the cost and complexity of the project.
Choosing Between Attached and Detached ADUs: Key Considerations
When deciding whether an attached or detached ADU is the best fit for your property, several factors come into play:
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Available Space: Detached ADUs require more land, making them better suited for larger lots. Attached ADUs are ideal for smaller lots where space is limited.
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Budget: Detached ADUs are typically more expensive to build, but they offer more flexibility and privacy, which can lead to a better return on investment. Attached ADUs are generally more affordable but come with constraints related to design and privacy.
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Privacy Requirements: Detached ADUs provide a higher degree of privacy, which may be more appealing if you’re renting out the unit or housing family members who prefer their own space.
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Long-Term Goals: If you’re considering selling the property in the future, a detached ADU may add more value to the property, as it’s often viewed as a completely separate living unit.
By carefully considering your goals, budget, and property layout, you can determine which type of ADU will best meet your needs. If you have any questions or need assistance planning your ADU project, the team at Alto ADU is here to help guide you through the process, from design to construction and beyond.