Your Complete ADU Cost Breakdown Guide


If you’re considering building an accessory dwelling unit, commonly known as an ADU, it’s important to understand the costs involved. ADUs can be a valuable investment, adding value to your property and potentially generating rental income. However, the cost of building an ADU can vary depending on several key factors. In this guide, we will provide a complete breakdown of the costs associated with building an ADU, so you can budget effectively and make informed decisions throughout the process.

Here at GreatBuildz, a free service that connects homeowners in Los Angeles, Ventura, and Orange Counties with reliable ADU contractors, we speak to homeowners every day about planning for an ADU construction project – here are some considerations to get you started.

Garage Conversion ADU Office

Understanding ADU Costs

When it comes to understanding the costs of building an ADU, it’s essential to consider the various factors that impact the final cost. The size of the ADU, the type of construction, the materials used, and the level of finish all contribute to the overall cost of the project. Additionally, there are design costs, development costs, and general contractor fees to take into account. It’s also important to budget for permits, fees, and site preparation costs. Fortunately, there are financing options available, such as loans or grants, to help offset the cost of building an ADU.


Key Factors Influencing the Costs of an ADU

The type of ADU, whether it’s attached, detached, or a garage conversion, will impact the cost. Site conditions, site preparation, and excavation costs are also important factors to consider. The cost of construction materials, plumbing fixtures, appliances, flooring, cabinets, countertops, siding, and roofing materials will also impact the final project cost. Additionally, the level of finish will affect the total cost of your ADU project. It’s important to budget for local impact fees, property taxes, and utility hookups as well.


Garage Conversion ADU

Plans, Permits, and Fees for Building an ADU

Before construction can begin, you’ll need to obtain the necessary plans, and permits, and pay the associated fees. The cost of permits and fees can vary depending on the location and type of ADU being built. It’s important to research and budget for all permit and fee costs before starting your ADU project.

Estimating Permit and Fee Costs

When estimating permit and fee costs, it’s important to consider the specific requirements of your location. Permit costs can vary greatly, but the average cost of permits for an ADU project is around $5,000 to $10,000. These costs typically include plan review fees, building permit fees, and environmental assessments. Additional fees, such as water and sewer connection fees, impact fees, and fire safety fees, may also apply.

Architectural Plans and Their Costs

Architectural plans are the first step in your ADU project, as they determine the design and layout of your accessory dwelling unit. Hiring an architect is essential to ensure your project meets your needs, local building codes, and all safety regulations. Professional architectural plans provide the necessary documentation for obtaining permits and working with contractors. The cost of architectural plans for your ADU project will depend on the size, complexity, and level of finish you desire, ranging from $5,000 to $15,000 or more. Investing in quality architectural plans upfront can save you time, money, and headaches during construction.

Garage Conversion planning and discussion with expert

Stick-built ADUs vs Garage Conversion ADUs: A Cost Comparison

There are two primary types of ADUs: stick-built ADUs and garage conversion ADUs. Stick-built ADUs involve new construction, which may have higher costs due to site preparation and development costs. You can expect costs for stick-built ADUs to range from $350 to $550 per square foot, or more for two-story structures. While stick-built ADUs may have higher long-term value and resale potential, garage conversion ADUs may be more cost-effective, utilizing existing structures. For a standard detached 2-car garage conversion, costs can start around $110,000 and go up to $200,000 or more, depending on complexity and materials. The choice between stick-built and garage conversion ADUs will depend on your budget, goals, and property limitations.


Labor and Material Costs in ADU Construction

Labor costs play a significant role in the total cost of your ADU project, as do material costs. It’s crucial to research the available materials to ensure they align your budget with your project goals. By considering these factors, you can effectively plan for the cost of your ADU construction.

Calculating Labor Costs

Calculating the cost of labor for your ADU construction project requires considering several factors. The size and scope of the project, as well as the project’s location, will impact the cost of labor. Labor costs are typically based on hourly rates, although some construction companies may offer fixed fees. Skilled labor, such as plumbing or electrical work, may cost more than general labor. Additionally, site preparation and excavation costs impact the total labor costs of your project. It’s crucial to compare quotes from construction teams and contractors to ensure you budget effectively for the cost of labor.

ADU Design Ideas

Material Costs: A Detailed Overview

Material costs play a significant role in the total project cost of your ADU. Finish materials, plumbing fixtures, appliances, flooring, cabinets, countertops, siding, and roofing materials all impact the final cost of your project. When budgeting for materials, it’s important to consider the type and quality, as costs can vary significantly. Finishing materials, plumbing fixtures, appliances, flooring, cabinets, and countertops should be budgeted for separately, as they are usually chosen and provided by the homeowner, and therefore generally excluded from contractor bids. However, building materials, such as for the foundation, framing, roofing, plumbing, electrical work, drywall, and insulation are typically provided by the general contractor. Other material costs may include plumbing and electrical upgrades, HVAC systems, and windows/doors. Discussing material responsibilities with your contractor will ensure everyone is on the same page.


Breaking Down Finish Material Costs

When it comes to finish materials, several key components impact the total cost of your ADU project. Flooring, countertops, cabinets, plumbing fixtures, windows, doors, and exterior materials can constitute a significant portion of your overall costs. Considering the durability, maintenance needs, and aesthetic appeal of the materials available will help you budget effectively for your ADU project.

Flooring Options and Their Costs

Flooring costs can vary widely depending on the type of flooring you choose for your ADU project. Hardwood flooring, known for its durability and timeless appeal, can range from $5 to $25 per square foot, while laminate flooring, a budget-friendly option, costs around $2 to $8 per square foot. Tile flooring, which offers water resistance and versatility, can cost between $3 to $15 per square foot, depending on the type of tile and design. Vinyl flooring, the most affordable option, can range from $1 to $5 per square foot. It’s important to consider the cost, durability, and aesthetic appeal of the flooring materials when budgeting for your ADU project.

contractor installing flooring

Countertops and Cabinets: A Cost Analysis

Countertops and cabinets are two of the most significant expenses in an ADU project – the type of materials you choose for your countertops, such as quartz, granite, or laminate, will impact the overall cost. Quartz or granite countertops can range from $50 to $200 per square foot, while laminate countertops are a more affordable option, ranging from $10 to $40 per square foot. Custom cabinets, built to your specifications, can cost up to $1,000 per linear foot, while semi-custom cabinets start as low as $500 per linear foot. When budgeting for your project, consider the materials, design, and size of your countertops and cabinets, as these costs can vary significantly.

Kitchen and Bathroom Fixture Costs

Kitchen and bathroom fixtures are essential aspects of your ADU design and budget planning. Fixtures such as sinks, faucets, and toilets come in a wide range of styles and price points. The cost of fixtures can vary widely based on the material and quality, with options ranging from budget-friendly to high-end luxury. Upscale finishes, such as brushed nickel or matte black, can add a touch of luxury to your ADU design. To keep costs down, consider shopping for fixtures at home improvement stores or online retailers. When choosing fixtures, consider the durability, functionality, and aesthetic appeal, balancing cost and value.

Window and Door Costs

The cost of windows and doors for your ADU project will vary depending on the materials, size, and style you choose. Vinyl windows and doors are typically the most affordable option, although they may not have the same aesthetic appeal as wood or aluminum. Wood windows and doors, while more expensive, provide greater insulation and durability. When budgeting for your project, it’s important to consider the long-term energy benefits of investing in higher-quality windows and doors.

Brick Siding

Exterior Siding and Roofing Costs

The cost of exterior siding and roofing materials will impact the total project cost of your ADU construction. There are several options when it comes to siding, including vinyl, wood, and fiber cement, each with its pros and cons. Vinyl siding is the most affordable, while wood siding provides a classic, natural look, and fiber cement siding offers durability and low maintenance. The cost of roofing materials will also vary, with traditional asphalt shingles being the most affordable option, and metal roofing providing durability and eco-friendliness at a higher cost. It’s important to note that new build construction projects in California are also required to incorporate solar. Consult with a professional contractor to better understand your siding, roofing, and solar options.

ADU Budgeting Tips

Budgeting effectively for your ADU project is crucial to ensure the project stays within your financial means. To budget successfully, prioritize your budget based on the most important aspects of your ADU, such as the size, finishes, or energy efficiency. Explore financing options, such as home equity loans or grants, that can help cover the cost of your project. Set aside a 10-15% contingency budget for unexpected expenses that may arise during construction. Consult with contractors, architects, and other professionals who can provide a detailed breakdown of the costs involved, helping you budget effectively for your ADU project.

Can Building an ADU Increase Your Property’s Value?

Building an ADU can have a significant impact on the value of your property, making it an attractive investment opportunity. Adding an ADU can increase the resale value of your property, providing potential rental income or the option of multigenerational living. ADUs offer the flexibility of additional living space, appealing to homebuyers seeking the potential of rental income or a separate living unit. To understand the potential impact of an ADU on your property’s value, consult with real estate professionals or appraisers familiar with your specific market conditions. They can guide you in making informed decisions about your ADU project.


Your Complete ADU cost breakdown Guide

Get Started on Your ADU Project Today!

Building an ADU requires careful planning and budgeting. It’s important to consider factors such as permits, architectural plans, labor costs, and materials when estimating the overall cost. Stick-built ADUs and garage conversion ADUs have different cost implications, so it’s essential to weigh the pros and cons of each option. Additionally, don’t forget to factor in the costs of finish materials, including flooring, countertops, cabinets, and fixtures. By taking the time to plan and budget effectively, you can ensure that your ADU project stays within your financial means. Remember, building an ADU not only provides additional living space but can also increase your property’s value. So, if you’re considering an ADU, make sure to consult with professionals and experts to get a comprehensive cost breakdown and create a successful project.

When it comes to planning and coordinating an ADU construction project, you shouldn’t have to go it alone – GreatBuildz is a free service that connects homeowners in Los Angeles, Ventura, and Orange Counties with reliable, thoroughly screened ADU contractors and provides project support from start to finish.


Hi, we're Paul and Jon - Co-Founders of GreatBuildz. We believe everyone deserves to find a great contractor, have a stress-free renovation, and enjoy their beautiful new space. There are so many contractors out there and it's often hard to tell the good from the bad... until it's too late. We started our company to help simplify your contractor search and help you have a stress-free renovation experience. We're always available to help, no matter where you are in the process. Click here to learn more about our story.

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