Understanding Accessory Dwelling Units (ADUs) in Fairfax County, Virginia

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Understanding Accessory Dwelling Units (ADUs) in Fairfax County, Virginia

An Accessory Dwelling Unit (ADU), known in Fairfax County, Virginia, as an Accessory Living Unit (ALU), is a secondary dwelling situated on the same lot as a primary single-family detached home. These units are designed to provide independent living facilities, including areas for sleeping, cooking, and sanitation.

What is an Accessory Living Unit (ALU)?

ALUs offer a versatile housing solution, accommodating extended family members, providing rental income, or serving as private guest quarters. They can be integrated within the main residence or constructed as separate structures, depending on specific regulations and property characteristics.

When Can You Establish an ALU in Fairfax County?

In Fairfax County, the establishment of an ALU is subject to specific criteria:

  • Property Type: Only single-family detached homes are eligible to add an ALU.

  • Approval Process: Interior ALUs (within the main dwelling) that meet all applicable standards can be approved through an administrative permit. Detached ALUs require a special permit and are permissible only on lots of at least two acres.

Key Restrictions and Requirements

Size Limitations

  • Interior ALUs: Must not exceed 800 square feet or 40% of the principal dwelling's gross floor area, whichever is less.

  • Detached ALUs: Permitted only on lots of two acres or more, with a maximum size of 1,200 square feet.

Occupancy

  • Either the main dwelling or the ALU must be owner-occupied.

  • The ALU can house no more than two individuals and may contain up to two bedrooms.

Entrances and Access

  • New external entrances for ALUs must be located on the side or rear of the dwelling to maintain the neighborhood's aesthetic.

  • There must be direct interior access between the ALU and the main dwelling through a finished, temperature-controlled, and fully enclosed space.

Parking

  • Properties must provide one additional on-site parking space beyond what is required for the principal dwelling.

Setbacks and Placement

Setbacks refer to the minimum distance that a structure must be located from property lines. In Fairfax County, while specific setback requirements for ALUs can vary based on zoning districts and property specifics, detached ALUs generally must adhere to the same setback requirements as the principal dwelling. This ensures adequate space between neighboring properties and maintains community character. It’s essential to consult the Fairfax County Zoning Ordinance or contact local zoning officials to determine the exact setback requirements for your property.

Building an ALU: What's Involved?

Planning and Design

  • Assess your property's suitability, considering lot size, existing structures, and local zoning regulations.

  • Develop design plans that comply with county standards and meet your intended use.

Permitting

  • Submit an application through Fairfax County's Planning and Development Department. Interior ALUs may qualify for an administrative permit, while detached units typically require a special permit, involving a more extensive review process.

Construction

  • Hire licensed professionals to undertake the construction, ensuring adherence to approved plans and building codes.

  • Schedule necessary inspections at various stages of the build.

Cost Considerations

The cost of building an ALU in Northern Virginia varies based on factors such as size, design complexity, and construction materials. On average:

CONVERSION ADU - GARAGE OR BASEMENT

  • Interior Conversions (e.g., basement or attic): Approximately $275 to $325 per square foot.

  • Detached New Constructions: Approximately $325 to $400 per square foot.

These estimates encompass materials, labor, permits, and associated fees. For a comprehensive assessment tailored to your project, consulting with a local contractor is advisable.

Visual Aids

To better understand ALUs, consider the following visual resources:

Conclusion

As housing demands continue to rise, Accessory Living Units provide a flexible and cost-effective solution for homeowners in Fairfax County. Whether you're looking to accommodate family members, generate rental income, or simply maximize your property's potential, an ALU can be a valuable addition to your home. By following county regulations and working with experienced professionals, you can successfully navigate the process. If you're ready to take the next step or seek personalized guidance and construction services to help you build an ALU that fits your needs, consider reaching out to Home Perfection Contracting, your local experts in home additions and renovations in Northern Virginia. Contact us today to start your project! Contact us today to start your project!

References

For a visual overview of Fairfax County’s proposed ADU regulations, you may find this video informative.