ADU/DADU

ADU vs. DADU: Which One Is Right for Your Property?

For homeowners looking to maximize their property’s potential, Accessory Dwelling Units (ADUs) and Detached Accessory Dwelling Units (DADUs)

James Carter
30 Jan 2026
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5 min read
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For homeowners looking to maximize their property’s potential, Accessory Dwelling Units (ADUs) and Detached Accessory Dwelling Units (DADUs) offer versatile solutions. Whether for additional rental income, guest accommodations, or a dedicated workspace, selecting the right option depends on various factors, including zoning regulations, cost, and intended use.

Understanding the Differences

- ADU (Attached Accessory Dwelling Unit): Integrated into the main residence, such as a basement apartment or home addition.
- DADU (Detached Accessory Dwelling Unit):
A standalone structure, like a backyard cottage, with independent utilities and a private entrance

Zoning and Permitting Requirements

Zoning regulations for ADUs and DADUs vary across King, Snohomish, and Pierce Counties. Most single-family lots can accommodate one or both, subject to size and setback restrictions. In Seattle, units can be up to 1,000 square feet, with no owner-occupancy requirement and flexible parking policies. Permitting timelines generally range from 4 to 12 weeks.

Cost and Project Timeline

- ADUs: Typically range from $200,000 to $300,000
- DADUs:
Generally cost between $250,000 and $350,000+
- Construction Duration:
Approximately 4 to 6 months after permit approval

Determining the Right Choice

- Rental Income: DADUs provide privacy, making them ideal for long-term tenants.
- Guest Accommodations:
ADUs offer convenience while keeping guests close to the main home.
- Home Office or Studio:
A DADU ensures a quiet, separate workspace.
- Multigenerational Living:
ADUs allow family members to reside nearby while maintaining independence.

Why Choose NBE LLC?

At NBE LLC, we specialize in navigating the permitting process, ensuring high-quality construction, and delivering seamless project management. Our expertise helps homeowners maximize their investment while creating functional and aesthetically pleasing living spaces. Contact us today to discuss your ADU or DADU project.