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How much does it cost to build a DADU?

Avio Homes

Cost to build DADU in Washinton State

Cost to build a DADU:

In the ever-evolving landscape of real estate, the concept of backyard homes, also known as Detached Accessory Dwelling Units (DADUs), has gained significant traction. These versatile structures offer homeowners in Washington State, particularly in cities like Seattle, Tacoma, and Olympia, an opportunity to maximize space, enhance property value, and even generate additional income streams. However, before diving into the exciting realm of backyard homes, it’s crucial to understand the costs involved. In this comprehensive guide, we’ll explore the intricacies of building a DADU in Washington State, shedding light on the expenses and considerations involved.

Understanding DADUs: A Brief Overview

Detached Accessory Dwelling Units (DADUs) are secondary living units built on the same lot as a primary residence. These standalone structures provide homeowners with the flexibility to accommodate multigenerational living arrangements, create rental opportunities, or simply expand their living space. DADUs come in various forms, including backyard cottages, granny flats, or garage conversions, and are subject to specific regulations outlined by local authorities.

The Benefits of Building a DADU

Before delving into the costs, let’s highlight the myriad benefits of investing in a DADU:

  1. Increased Property Value: Adding a DADU can significantly enhance the value of your property, making it a lucrative long-term investment.
  2. Rental Income Potential: Renting out the DADU provides homeowners with a steady source of passive income, helping offset mortgage payments and other expenses.
  3. Flexibility and Versatility: DADUs offer versatile living spaces that can be customized to suit various needs, from guest accommodations to home offices or studios.
  4. Multigenerational Living: With aging populations and changing family dynamics, DADUs offer a viable solution for accommodating elderly parents or adult children while maintaining privacy and independence.
  5. Environmental Sustainability: Building smaller, more energy-efficient structures aligns with sustainable living practices, reducing carbon footprints and promoting eco-friendly lifestyles.

Factors Influencing DADU Costs

Several factors influence the cost of building a DADU in Washington State, including:

  1. Size and Design: The size and complexity of the DADU design directly impact construction costs. Larger, more intricate structures will naturally require a higher investment.
  2. Site Preparation: Site preparation, including excavation, grading, and utility connections, can add significant expenses to the overall project cost.
  3. Materials and Finishes: The choice of materials and finishes, such as flooring, cabinetry, and fixtures, can vary widely in cost and quality, affecting the final price tag.
  4. Permitting and Regulatory Fees: Obtaining the necessary permits and complying with local building codes and regulations entail additional expenses that should be factored into the budget.
  5. Labor Costs: Labor costs, including contractor fees and subcontractor wages, play a crucial role in determining the overall cost of construction.

Cost Breakdown by City

Let’s explore the estimated costs of building a DADU in key cities across Washington State:

1. Seattle

As one of the most populous cities in Washington State, Seattle offers abundant opportunities for DADU development. However, the cost of construction in Seattle tends to be higher compared to other areas due to factors such as land prices and labor demand.

  • Estimated Cost: The average cost of building a DADU in Seattle ranges from $150,000 to $250,000, depending on various factors such as size, design, and location.

2. Tacoma

Situated south of Seattle, Tacoma presents a more affordable alternative for DADU construction while still offering proximity to urban amenities and employment opportunities.

  • Estimated Cost: Building a DADU in Tacoma typically costs between $120,000 and $200,000, making it a relatively cost-effective option for homeowners.

3. Olympia

As the capital of Washington State, Olympia boasts a vibrant community and a diverse housing market. Building a DADU in Olympia offers homeowners the chance to enjoy the city’s cultural attractions and natural beauty.

  • Estimated Cost: The average cost of constructing a DADU in Olympia ranges from $130,000 to $220,000, depending on factors such as size and design preferences.

Avio Homes: Your Partner in DADU Construction

At Avio Homes, we specialize in designing and building custom DADUs tailored to your unique needs and preferences. With years of experience in the construction industry and a commitment to quality craftsmanship, we’re dedicated to bringing your vision to life while adhering to budgetary constraints and timelines. Whether you’re envisioning a cozy backyard cottage or a sleek modern studio, our team of professionals is here to guide you through every step of the process, from initial consultation to final inspection.


Building a DADU in Washington State offers homeowners a myriad of benefits, from increased property value to rental income potential and versatile living arrangements. While the cost of construction may vary depending on factors such as city location, size, and design preferences, investing in a DADU can yield significant returns in the long run. By partnering with a reputable construction company like Avio Homes, you can embark on your DADU journey with confidence, knowing that your project is in capable hands. Unlock the potential of your property and create your dream backyard home today!

Contact Us today for a free, no-risk, no-obligation assessment to see if an ADU or DADU is right for your property!

About Avio Homes

At Avio Homes, we specialize in building backyard homes, tiny homes, and DADU's. We have over 110 years of combined experience in the home-building industry.