Building an ADU (Accessory Dwelling Unit) can be an excellent investment, whether you want a rental income or provide a cozy space to additional family members. But, it is important to understand the costs of building this secondary unit.
Are you curious about how much it costs to build an ADU in California? You have landed at the right place where we will demystify the expenses associated with ADU construction, breaking down the key factors affecting your budget.
In this blog, you can learn about the cost of everything right from permits and construction materials to labor and hidden expenses you might not have considered.
The Rise of ADUs in California
The demand for housing is increasing, and people are looking for more flexible living options. ADUs are a practical and cost-effective solution to meet this demand. They are becoming a popular option in the US, due to lesser restrictions and waiver of additional fees to make these housing units affordable for homeowners.
In California, the number of ADU permit applications is increasing every year. The demand for ADUs is the highest in South California and is also fast rising in Los Angeles.
How Much Does an ADU Cost in California?
ADUs are versatile living spaces that can make your house even better. Making an ADU can cost about $200,000 to $400,000, depending on factors like ADU type, location, size, and other details.
Before starting, let’s look closely at the soft costs (costs excluding labor and material) and hard costs (costs related to labor and material) of building an ADU.
What Are the Soft Costs Involved in an ADU?
Soft costs must be accounted for when building an ADU. In California, soft costs usually comprise 10-15% of the ADU’s total cost. It is prudent to include the soft costs in your budget planning, as you will be well-prepared for the ADU project and avoid unexpected expenses. Let’s take a look at the sample breakdown of the soft costs:
Average architectural cost: $20,000-$30,000
Average consultation cost: $8,000-$12,000
Average permit costs:
- Building permit fee: $2,000-$10,000
- City fee: $3,000-$11,000
Please note these costs can vary depending on the scope of the project, its location, and other factors.
1. Architectural Design Cost
The initial stage of building an ADU involves designing and creating the blueprints. Usually, the architectural expenses vary between 10-15% of the total project cost. So, if your ADU is expected to cost $200,000, an architect’s fee would set you back by $20,000-$30,000.
2. Consulting Cost
When planning an ADU project, you will need some basic consultants. These include a structural engineer who calculates the frame & structure, an energy consultant who checks how energy-efficient your ADU will be according to Title 24 rules, and a surveyor who determines the exact property lines and other measurements. The consultation may vary depending on the project.
The average cost of these consulting services in California is between $8,000 and $12,000. If any project needs additional support, the consultation cost may rise.
3. Permit Cost
Before you can start building your ADU, you will need permission from your local planning department. These permissions are called permits, and their costs vary depending on your location. Building permits range from $2,000 to $10,000, whereas city fees can range from $3,000 to $11,000. This amount can change depending on the size and value of your ADU.
Every city has its own set of rules and requirements, so it is important to contact your local authorities to know which permits you need and how much they cost.
What Are the Hard Costs?
Hard costs are the costs of the labor and materials needed to build the physical structure of your ADUs. It includes the foundation, frame, roof, electrical & plumbing systems, insulation, windows, doors, flooring, and finishes.
The hard costs can vary depending on the size, design, quality, and complexity of your ADU. On average, hard costs make up 85-90% of the total cost of building an ADU in California.
1. Site Preparation Cost
Preparing your site is crucial to ensure your ADU stands strong and has all the needed connections. Sometimes, you might need to level the ground, and its cost depends on the condition of your property. Factors like rocks, pipes, or wires under the ground can make site preparation expensive.
After the site is all set, you can create a strong base for your ADU. A sample of site preparation costs for building an ADU can include approximately $50-$200 per cubic yard for excavation, $4,200-$13,200 for concrete foundations, $4-$8 per square foot for a concrete slab, and $3,200-$9,000 for retaining walls.
2. Construction Cost
The biggest expense in building an ADU is the construction work. This cost can vary depending on the complexity and how uniquely designed your ADU is. Usually, creating a 400-600 sq. ft. ADU might set you back around $200,000-$300,000. But, with specific requirements and finishes, the construction cost can increase.
3. Utilities & Interior Cost
Your ADU’s electrical, plumbing, and HVAC systems must follow the building rules. To make the inside of your ADU look nice, you have to spend around $10-$60 for every square foot. If you want to add more stuff, the cost will increase even more. These costs depend on your location and some other factors.
Factors Affecting the Cost of Building an ADU
It is important to know all the possible expenses to ensure you stay within your budget. When you collaborate with an expert team like BFPM, who are open about their costs, rest assured you will not encounter any hidden costs. Consider these important factors at the time of estimating the cost of building an ADU:
1. Size
The construction cost of an ADU can vary based on how big it is. The newly constructed ADUs are around 600-1200 square feet in size. In California, according to rules, ADUs can’t be smaller than 150 sq. ft. or bigger than 1,200 sq. ft.
| ADU Size (sq. ft.) | Average Min Price | Average Max Price |
| 400 sq. ft. | $60,000 | $120,000 |
| 600 sq. ft. | $90,000 | $180,000 |
| 750 sq. ft. | $112,500 | $225,000 |
| 1,000 sq. ft. | $150,000 | $300,000 |
| 1,250 sq. ft. | $180,000 | $360,000 |
In terms of space, detached ADUs need more rooms and their own space rules. On the other hand, conversion ADUs use existing spaces and don’t need an extra room.
2. Location
The price for each square foot of an ADU varies from place to place. It depends on how much the houses cost in your area and other factors. However, since more people are looking for affordable houses, rules, and help is available to make building and renting ADUs easier.
3. Amenities
Adding amenities can make your ADU more useful, attractive, and valuable. When it comes to amenities, you need to think about the use of your ADU. For instance, if it is for an elderly member, you can add things to make it easier for them to get around. You can use design tricks like big windows and skylights to give a bigger look.
Don’t worry if you are on a tight budget. You can choose the right company to help you get the most out of your ADU.
How Can You Cut ADU Costs With BFPM?
While choosing an ADU company, think about each stage of the ADU process, from creating a floor plan and imagining your ADU to building. It is best to rely on an expert team like BFPM that can support you at every stage and ensure the result is cost-effective and matches your requirements.
BFPM can help you cut ADU costs in several ways. We have relationships with various vendors, which can help you negotiate lower prices for your ADU construction. We are already in ADU construction projects from start to finish, so you can trust us for the overall cost of your ADU.
Our property managers are always available to assist you with expert advice and guidance on ADU projects or any other real estate project. Feel free to contact us for any real-estate query.
Trevor Henson
Trevor Henson is an experienced entrepreneur (10+ highly-successful start-ups) and property investor with a demonstrated history of building and leading teams in investment property management environments, maximizing returns for property owners, and optimizing properties through construction management and re-positioning. He…Learn more about how we can help. Customized solutions for large portfolios!