What to Look for in an ADU Estimate

Have you been considering adding an ADU to your property but are unsure about what to look for in an estimate? You’re not alone. An accurate ADU estimate is crucial when planning a project like this. In this blog post, we will provide you with all the information you need about ADU estimates, including what’s included and what’s not, the key components of an estimate, and how to compare different estimates and expected costs in Southern California. We will also shed light on some common mistakes that people make while getting ADU estimates. With our help, you’ll be able to make informed decisions when selecting the right contractor for your project and have confidence in the success of your ADU.

Here at GreatBuildz, we speak with clients every day about their ADU projects. GreatBuildz is a free service that connects homeowners with reliable, pre-screened home contractors in Los Angeles, Ventura, and Orange Counties, then provides ongoing project support to ensure a stress-free experience.

Understanding ADU Estimates: An Overview

Properly understanding ADU estimates is crucial for homeowners as it allows for better planning and budgeting. These estimates can cover various components such as design, materials, and construction costs. Homeowners should consider getting multiple estimates to compare prices and make informed decisions. It’s important to note that the total cost of an ADU depends on factors like the size of the ADU, the type of construction (stick-built or garage conversion), and the specific requirements of the project.

ADUs are considered a good investment as they can provide additional income through renting and can increase the value of single-family homes. By understanding the various costs associated with building an ADU, homeowners can make well-informed decisions when it comes to their property.

What is an ADU?

An ADU, or accessory dwelling unit, is a secondary living space built on the same property as the main home and can be used for rental income or to accommodate family members. They can be either attached or detached from the main house and can provide affordable housing options while increasing property value.

The Importance of an Accurate ADU Estimate

Proper budgeting is crucial for any ADU project, and an accurate estimate plays a vital role in achieving this. It helps homeowners avoid unexpected costs and financial issues during construction. By providing transparency, a detailed estimate allows homeowners to make informed decisions. Additionally, an accurate estimate sets realistic budget expectations for the ADU project. In some cases, homeowners may even be able to secure financing for their ADU construction using the estimate. Ensuring an accurate ADU estimate is essential for a successful and well-planned project.

Accessory Dwelling Unit

What’s Included and What’s Not in an ADU Estimate?

An ADU estimate should include all the costs associated with constructing an ADU, such as design, construction, labor, and building materials. However, it may not cover additional expenses like fixtures, finishes, and appliances. Make sure you and your contractor agree on what will be included.

The Inclusions

When working with a design/build team, both architectural expenses and construction costs are typically included in the ADU estimate. Construction costs encompass materials like lumber, drywall, and other building materials. The estimate may also take into account essential components such as foundation, framing, roofing, and insulation. Plumbing, wiring, and HVAC systems may be part of the estimate as well. Additionally, allowances for flooring, doors, and windows are sometimes factored in. A good estimate provides homeowners with a comprehensive understanding of what to expect in terms of inclusions and exclusions.

The Exclusions

When it comes to an ADU estimate, there are certain exclusions you need to be aware of. These may include permits, landscaping, and site preparation, such as soil reports or grading. It’s also important to understand that there may be additional costs that can arise during construction due to unforeseen circumstances such as mold discovery or the need to upgrade electrical panels. Additionally, make sure to clarify whether appliances, fixtures, and finishes are included in the estimate or not. Hidden costs can have a significant impact on your overall budget, so it’s crucial to be on the same page as your contractor.

Key Components of an ADU Estimate

Design and architectural expenses, construction costs (including labor and materials), as well as plumbing, wiring, and HVAC systems, are all factors to consider in your ADU estimate. Understanding these components will help you determine the total cost of building an ADU.




Architectural Plans for ADU

Design and Architectural Expenses

Design and architectural expenses involve creating detailed plans and blueprints for the ADU, ensuring that it meets all building codes and regulations. The cost of these services can vary depending on the size and complexity of the ADU design but can range anywhere from $3k-15k. Design professionals may alternatively charge a fixed cost or a percentage of the overall project total. To ensure a well-designed ADU, it is advisable to hire experienced professionals who specialize in ADU design.

Permit Fees

The cost of permit fees can vary depending on your location and local building regulations. Different jurisdictions may have specific requirements and fees for ADU construction, including Title 24 requirements. It’s important to factor in these costs when estimating the total cost of building your ADU. Taking care of the permit fees upfront will help ensure a smooth and hassle-free construction process. Consulting with local general contractors who are familiar with the permit process can help you navigate through the necessary paperwork and requirements.

Construction Costs

Construction costs for an ADU will generally cover the labor, materials, and equipment needed to build the structure. Working with reputable contractors is crucial to ensure quality workmanship within budget. It’s important to consider the size and complexity of the ADU, as well as the square footage when estimating construction costs. A detached ADU or a prefab option may have different cost considerations compared to a stick-built ADU. By understanding the total cost of building an ADU, homeowners can make informed decisions and determine if it’s a good investment.

Material Costs

Material costs for your ADU can include appliances, fixtures, and interior finishes. The type and quality of materials chosen can vary widely and therefore have a significant impact on the overall cost of the ADU. Homeowners can save money by selecting cost-effective yet durable materials. Researching different suppliers and comparing prices can also help reduce material costs. Because of the wide range of available finish materials, contractors may exclude these items from their estimates, allowing you the freedom to choose them according to your own budget and preferences.

How to Compare Different ADU Estimates?

When comparing ADU estimates, it’s important to consider a few key factors. Look for estimates that provide a detailed breakdown of costs, preferably itemizing the costs for each phase of construction (framing, plumbing, electrical, drywall, etc.). You should ensure that each contractor is bidding the exact same scope of work to avoid confusion. And remember, the lowest bid isn’t always the best or most inclusive option.

Comparing Apples to Apples

Having architectural plans for your ADU in place before getting estimates can help ensure all your contractors are bidding on the same project specifications. Additionally, comparing the inclusion of finishes and fixtures is crucial – some estimates may include allowances for items like cabinets or countertops, or windows and doors, while others may not. To make a fair comparison, it’s also necessary to check that all estimates include the same items and/or materials.

If there is any vague or unclear language in an estimate, it’s best to ask questions upfront to avoid potential disagreements later. Remember, comparing estimates apples to apples will help ensure you are able to make the most informed decision for your project.

ADU estimate Detached Garage for ADU Conversion

Watch Out for Hidden Costs

It’s also important to be mindful of potential hidden costs that may arise. These can include utility connections or any site preparation that may be deemed necessary and not included in the estimate. If you are planning a garage conversion ADU, you may also want to check for any foundation, structural, or roofing work that is not accounted for – often the estimate reflects the ‘best case scenario’ for these items, but there might be more work needed than anticipated once construction begins, especially if you have an older home.

Additionally, unexpected plumbing or electrical expenses, such as trenching or upgrading panels, should be factored in as well. Changes or upgrades, like custom cabinets or high-end doors, may increase the overall cost as well. If you are unsure about any of these items, you should discuss them with your contractor in further detail.

Common mistakes to avoid when getting an ADU estimate

When reviewing your ADU estimates, it’s important to avoid being lured in by estimates that are significantly lower than others. These estimates may not include all the necessary costs, so it’s you’re right to be wary of them – if it sounds too good to be true, it probably is. Additionally, it’s crucial to consider the reputation and experience of the contractors you are getting estimates from – make sure to thoroughly research and vet all candidates before making a decision.

Don’t overlook the importance of a detailed contract – it’s essential to have a contract that clearly outlines all terms and conditions of the payment schedule to avoid any misunderstandings later on. Lastly, don’t rush into a decision without proper research -take your time to explore different options and consider all factors when planning your ADU.

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Expected ADU Costs in Southern California

Location can of course have a significant impact on the overall cost of your ADU. In major cities like Los Angeles, expect higher costs due to factors such as high demand, strict building codes, and material and labor availability. Don’t forget to factor in the additional costs of permits and fees, which can vary depending on the specific city or municipality. Finally, keep in mind that the size and design preferences of your ADU will also impact the cost, so, carefully consider your budget and prioritize your needs while keeping these factors in mind.

Average Cost of ADUs in Southern California

When it comes to ADUs in Southern Californian, factors such as location, size, materials, and design all play a role in determining the total cost. Depending on the complexity of the project, ADUs in this area can range from $120,000 to $350,000. It’s important to note that Los Angeles ADU costs may be higher than the national average, so it’s crucial to consider location when researching. Keeping these factors in mind as you explore building an ADU will help you plan financially and avoid sticker shock.

Factors Affecting the ADU Costs

Factors that can affect the cost of an ADU in Southern California will include the type of ADU, such as a garage conversion, prefab, or stick-built. Costs for converting a detached garage may be higher than an attached garage due to additional plumbing and sewer requirements. Upgrades to older homes, such as plumbing or septic systems, HVAC, wiring, foundation, or roofing, can also increase costs. The level of finish and interior fixtures chosen will also greatly impact the overall cost. And of course, property value and location can also affect the cost of an ADU project.

How Do Design Preferences Influence the Cost of an ADU?

Design preferences can play a significant role in the cost of an ADU. Factors such as layout, materials, finishes, and architectural features can impact the overall budget. Higher-end choices and customization may increase costs. Communicating your budget and preferences clearly with your design team can help ensure you balance design preferences with budget considerations.

Loft Bed in ADU

Ready to start getting estimates on your ADU project?

When reviewing ADU estimates, it’s crucial to consider all the factors that go into the final cost, from design to permits to finishes. Remember to compare estimates based on similar criteria and watch out for any hidden costs. Additionally, be mindful of design preferences and how they can influence the overall cost of your ADU project. If you’re ready to start your ADU project, reach out to our experts for a personalized estimate and guidance.

Here at GreatBuildz, a free service that connects homeowners in Los Angeles, Ventura, and Orange Counties with reliable general contractors, we help people every day to better understand the ADU costs, scope, and details for their prospective projects.


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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