ADU Calculator

How Much To Build An ADU

Plan Your ADU Constuction Budget

What does it cost to build an ADU?

Our ADU Cost Calculator is designed to provide you with a detailed estimate of the costs involved in building an Accessory Dwelling Unit (ADU). Simply input your project details, and our calculator will break down the estimated expenses, helping you to plan your budget effectively. Whether you’re looking to add a detached unit or convert existing space, understanding the financial commitment is crucial.


Planning an Accessory Dwelling Unit (ADU) in California can be a wise investment. Our California ADU Calculator simplifies the budgeting process, helping you estimate the cost of building an ADU based on your specific needs and location. For initial budgeting, expect the price per square foot for constructing a detached ADU to range between $395 and $600 or more. This estimate is applicable for units sized from 400 to 1200 square feet. Notably, about 80-85% of your investment will go towards vertical construction costs, covering the building structure and standard finishes.

ADU Vertical Cost Calculator

Vertical build cost would cover the construction of the dwelling excluding any site work and external utilities, making it a crucial figure for budgeting the main part of the project. Use our ADU Calculator to get a reliable estimate of the primary costs involved in building an ADU.

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What Is The Total Cost to build an ADU?

When estimating the total cost to build an ADU, take into account all associated expenses. Design costs are typically around $10,000, while permitting fees can vary widely based on the municipality, ranging from $2000 to $5000 per. Sitework usually comes in at about $25,000. Depending on your property’s specific requirements, you might also need to allocate an additional $30,000 to $50,000 or more. These costs are customized to the unique needs of your site to ensure that your new ADU complies with all local regulations and integrates seamlessly with your existing structures..


The cost to build a detached ADU is primarily influenced by the unit’s size, site conditions such as grading and utility locations, and local permitting requirements, which may include fees for building plan checks and schools. Vertical build costs are affected by the chosen finishes; our pricing includes a standard level of finish, complete with appliances and fixtures

ADU Feasibility & Site Assessment $2995+

We prioritize early completion of tasks that many contractors typically handle later in the process. Our goal is to evaluate the feasibility and all associated costs of building an ADU on your property. Initially, we develop a site plan, survey existing utilities, assess electrical panel capacities, and prepare a feasibility report with your chosen ADU floor plan placed on your property. 


This early work enables us to provide a preliminary budget for your project before advancing to the construction document stage. Everything done in this phase is a step towards producing the comprehensive set of ADU plans required for city approval.

ADU Construction Design And Drawings: $7500+

Despite using standard ADU designs, each ADU must be customized and to your property specifics to enable us to prepare and submit construction documents (CDs) and a complete application package, including all necessary forms, to the city. 


This detailed package encompasses all essential architectural design, structural engineering, title 24 compliance, building code consultations with the city, permit expediting, and any requisite revisions. We manage everything required to secure ADU permits. The cost for one-story plans start at $7,500, with additional stories or units necessitating extra requirements and increased costs for the CDs.

Additonal Design Work For Complex Projects: $2500+

(Only in specific situations) In the event you may require more complex structural designs and floor plans etc, that are specifically tailored to your unique needs. If you are considering constructing multiple ADUs, need to incorporate a septic system, or have to address unique foundation challenges, expect the design phase to typically extend by an additional 3-4 weeks. 

This additional time is crucial for ensuring thorough customization and necessary modifications to the plans. Such detailed attention during the design process guarantees that your customized ADU plans align precisely with your specific property requirements and preferences.

Property Reports: TBD

(Only in certain circumstances) Depending on your local jurisdiction and the specific location on your property where you plan to situate the ADU, your project might necessitate extra property reports to ensure accurate planning for the Accessory Dwelling Unit. Examples of these additional reports could include a comprehensive survey, detailed title report, thorough soils analysis, and precise grading plans. 


During our initial discovery phase with you, we will evaluate the necessity for each of these reports. This evaluation is a critical part of our process as we prepare a detailed proposal for your project, ensuring that all potential requirements and obstacles are identified and addressed upfront to streamline the planning and building of your ADU.

Permitting & Fees: $5000+

While numerous fees associated with ADU construction have been waived, there are still several fees that you will need to consider. A general guideline is to anticipate around $10 per square foot in ADU permit fees, though this amount can vary widely depending on the city and the specific size of the unit. 


For ADUs under 750 square feet, no impact fees are required, which can significantly reduce overall costs. However, for ADUs exceeding 750 square feet, impact fees generally become applicable and are often calculated based on the proportion of the ADU’s size relative to the primary residence. In addition to these, sewer and utlilty fees must also be factored into the budget, ensuring all necessary utilities are properly integrated with your new ADU.

Site Conditions: $9000+

Each jurisdiction requires preliminary and ongoing steps to establish site protection Best Management Practices (BMPs), position temporary facilities such as toilets and dumpsters, and stake building corners. 


According to regulations, it is also necessary to conduct soil compaction testing and perform Home Energy Rating System (HERS) testing to meet energy efficiency standards. Additionally, we include a final cleaning of the ADU and entire consruction site to ensure that the Accessory Dwelling Unit is pristine and ready for move-in. This approach ensures compliance with all local regulations and prepares the site adequately for the construction and completion phases, providing a seamless transition to your new ADU.

Site Work $25000+

For a level lot with proper access for construction machinery, preparing a suitable foundation pad for an ADU typically costs approximately $25,000.


This estimated cost includes crucial activities such as trenching to lay the necessary utility lines that will service the ADU, as well as connecting these utilities. Additionally, the sitework encompasses finish grading, a vital step that helps establish effective drainage away from the structure, thereby mitigating potential issues related to water infiltration.

The extent of preparation required can vary based on the specific characteristics of the lot and the stipulations set by local building codes. 


In some cases, more comprehensive sitework might be necessary to comply with all regulatory requirements and to ensure that the construction phase proceeds without any complications. Factors such as soil stability, slope of the land, and existing underground infrastructure can all influence the scope and cost of the preliminary work needed to secure a stable and compliant build environment for your ADU.

Vertical Construction: TBD

The cost of vertical building construction for an ADU typically ranges from $200,000 to over $400,000. This pricing includes the complete construction of the ADU starting from the ground up, initiated with a slab-on-grade poured foundation that establishes a robust base for the entire structure. This foundational step is crucial as it ensures the stability and durability of the ADU. 


Following the foundation, the construction involves the erection of the building’s framework, which forms the core structure. Additionally, the price encompasses the installation of standard finishing materials that are essential for both the interior and exterior completion of the ADU, giving it a functional and aesthetic appeal.


For potential builders looking to understand what these costs entail in more detail, our ADU Calculator is a valuable tool. It offers a range of examples of vertical build construction costs. This resource aims to ensure full transparency and assists in helping you grasp the scope of your investment, outlining every aspect that is included in the ADU construction pricing.

Material Upgrades: TBD

Standard finish materials are included in the vertical build calculator guideline. These basic finishes comprise essential elements such as electrical and plumbing fixtures, cabinets, quartz countertops, selected from our standard packages, which are carefully chosen to ensure both functionality and aesthetic appeal right from the start. 


For those desiring a more customized or upscale finish, our extensive design catalog offers a range of optional upgrades to enhance the interiors of your ADU. You can select from premium options like sophisticated tiled showers, expansive kitchen islands, and high-end appliances. 


These enhancements allow you to personalize your living space further, increasing both its value and comfort. Opting for such upgrades not only tailors your ADU to better reflect your personal taste and lifestyle but also adds a touch of luxury and exclusivity, making your new space uniquely yours. This approach ensures that each ADU we build can be as basic or as luxurious as the homeowner desires, providing flexibility and choice in the customization process.

ADU Costs: Higher Price Per Square Foot Explained

We understand that it might seem surprising at first to see the cost per square foot for Accessory Dwelling Units (ADUs) higher compared to Single Family Residences (SFRs). It’s important to recognize that while ADUs are generally smaller, they encompass nearly all the same fixed costs as any residential building, which spreads less across their compact size, hence the higher per square foot cost.

However, building an ADU offers a valuable opportunity. These structures are an excellent way to add a significant asset to your property, provide housing for family members or generate rental income. The investment in an ADU not only enhances the functionality and value of your property but also offers long-term benefits that outweigh the initial costs.

How much does an ADU cost

Boost Your Home's Value

Adding a custom ADU to your property can significantly enhance its value, making it a smart investment for homeowners. An ADU not only provides additional living space that can be used for family, guests, or as a rental unit for extra income, but it also increases the overall square footage of your property, thereby boosting its market value. This added value comes from the flexibility and functionality that an ADU offers, making your home more attractive. to potential buyers. With the growing demand for affordable housing and multi-generational living solutions, an ADU can make your property stand out in the real estate market, providing a high return on investment. 

With a Custom ADU

Why We Build ADU's Better

We are dedicated to surpassing the standard approaches often taken in the construction of Accessory Dwelling Units. Unlike other contractors who might defer critical tasks to later stages, we adopt a proactive approach right from the outset. This methodology not only streamlines the building process but also ensures that every aspect of the construction is thoroughly planned and executed with the highest standards in mind.


We front-load crucial tasks such as feasibility assessments, site preparations, and detailed planning to mitigate any unforeseen issues well before they can become problematic. This preemptive strategy allows us to maintain tight control over the construction timeline and budget, ensuring that each ADU we build meets our rigorous quality standards without compromising on the bespoke needs of our clients.


Our commitment to excellence is reflected in the superior quality of our workmanship, the durability of the materials we choose, and the innovative designs we implement. Each ADU we construct is not just a building; it’s a carefully crafted space tailored to enhance functionality and aesthetics, providing lasting value to homeowners.


By choosing us for your ADU project, you’re opting for a partner who prioritizes precision, transparency, and customer satisfaction from the ground up. We build ADUs better because we believe in the potential they have to transform properties and lives through thoughtful and efficient design and construction

Get Started in 10 Minutes!

Ready to explore building an ADU with us? 

It only takes a 10 minute introduction call to see if we’re the perfect fit for your custom ADU project! 


  • Reach out with a quick initial call with our expert team. In this brief conversation, we’ll discuss your needs, share a bit about our process, and determine if we’re the right match. 
  • No pressure, just a friendly chat to see if we’re the right fit for your Accessory Dwelling Unit (ADU) project.

Whats Next:

  • Initial Call: A 10-minute chat to discuss your goals and basic details. No sales pressure, friendly conversation.
  • Detailed Follow-Up: If we’re a good fit, we’ll schedule a 30-minute call to dive deeper into your project specifics.
  • Site Visit: Finally, we’ll arrange a site visit to assess your property and provide a detailed proposal.

Start with Your Vision

Your vision is all that it takes to get started on building your custom Accessory Dwelling Unit. We make the design an constructionprocess streamlined and hassle free, taking care of the finer details so you don’t have to. 

End with Your Perfect ADU

How Much Does It Cost To Build An ADU

Are You Ready For A Great ADU Buiding Experience?

We’re here to make your dream ADU a reality. With our dedication to quality, innovation, and client satisfaction, we ensure a seamless and enjoyable experience from start to finish. Let’s build your perfect ADU together – get in touch with us today!