In California, single-family properties are allowed one detached ADU, one conversion ADU, and one JADU. Multifamily properties are allowed two detached ADUs, plus the conversion of non-habitable space into ADUs up to 25% of the existing unit count.
Placement options include:
Each ADU building project is unique. The cost will depend on a range of factors:
On average, the material and labor costs (hard costs) to build an ADU are $290-$300 per square foot for a single-story detached or attached ADU, while garage conversions are lower, typically $215-$225 per square foot. Second-story additions are typically the most expensive options, averaging between $325-$350 per square foot.
Fees may be waived depending on the area. An ADU Geeks Feasibility Study will show the estimated permitting fees
Generally, stick-built ADUs have a 10-year warranty.
You’ll most likely be able to build an ADU, but it depends on your state and local laws and regulations. You may even be able to build multiple!
The budget for soft costs (design fees, permit fees, etc.) typically ranges from $22k-$30k for a single ADU, and hard costs (construction expenses) are typically around $225-$350+ per square foot.
From our experience, the average permit fee for ADUs in California is $1400. Permit review fees can vary from $1500-$4500 and beyond, depending on your location and other factors.
Generally, stick-built ADUs have a 10-year warranty.
Focus on the ADU's ultimate purpose rather than maximizing size. A studio ADU is usually less than 300 square feet, a one-bedroom ADU between 400-600 square feet, and larger than 600 square feet typically accommodate 2 or more bedrooms.
Options to finance an ADU include a cash-out refinance, home equity line of credit, renovation loans, or personal loans.
ADU floorplans for California typically cost $13k+.
Generally, stick-built ADUs have a 10-year warranty.
The California ADU size limit is generally up to 1200 square feet. Local municipalities may allow for larger units.
Lenders typically consider your credit score, cash assets, income, and the property’s value.
ADU Geeks typically does not submit outside plans. During permit review, there are almost always minor to major revisions that have to be made, and we cannot edit someone else’s plans.
Generally, stick-built ADUs have a 10-year warranty.
On a residential single-family property in California, you can typically have one ADU, one junior ADU, and one conversion ADU. Local laws may affect this limit. Book a free consultation with ADU Geeks to learn more.
Yes, lending caps depend on the loan type and your location.
Yes, through vetted General Contractors who are experienced in residential construction.
A Junior Accessory Dwelling Unit, also known as a JADU, is an ADU that converts a space in an existing house to a separate dwelling. JADUs have their own set of rules, just like ADUs, and are typically limited to a maximum of 500 square feet. Additionally, the owner of the property is required to sign an owner-occupancy agreement in most jurisdictions.
Our team of experts can help you plan for all the normal costs of building an ADU, including design fees, permit fees, cost of construction, type of financing, and the timing of the financing becoming available during your ADU project
Yes, as an "owner builder," though you must carry the necessary insurance and workers' compensation.
Stick-built ADUs are constructed onsite with materials brought to the site.
We have lending partners that we can connect our clients with that may be able to help you finance your ADU.
Yes, although the General Contractor cannot warranty work they didn't perform.
Prefab ADUs are built offsite and shipped to the property, offering a cleaner and faster construction process.
The addition of an ADU typically increases a California home's property value by $200,000 to $500,000, depending on factors such as size, location, and type.
Typically 9-16 weeks, not including design and permitting time.
Stick-built ADUs offer flexibility in design and usually have higher resale value but are more costly and take longer to build. Prefab ADUs are more affordable and quicker to build but offer limited customization and typically have a lower resale value.
The California Housing Finance Agency offers ADU grants to individuals who are considered low-income based on your county. Find your county’s limit on the CalHFA website.
Generally, stick-built ADUs have a 10-year warranty.
Building an ADU will be assessed for property taxes but won't trigger a reassessment of your main house's value.
Property taxes are approximately 1% of the ADU's assessed value. For an ADU valued at $120,000, the yearly property taxes would be $1,200.
Yes, building an ADU is tax deductible in California! If you choose to rent out your ADU, any income you make is taxable.
You can depreciate the cost of the ADU over 27.5 years if rented out. A certified cost segregation study can accelerate depreciation by categorizing expenses into different useful-life categories.
Consider the local rental market and amenities offered by your ADU. Rental income potential varies widely depending on location and property features. Our feasibility study can help you determine local rental averages.
We can perform the cost segregation study, leveraging our expertise in taxation to help you maximize your depreciation
The options for your ADU building will depend on the limitations of your property and the unique ordinances for your local jurisdiction. Even if you choose pre-approved ADU plans for San Diego, you’ll still need to do more than choosing a plan to obtain the right permits and customize the plans to your property.
Generally speaking, there are four options for an ADU building. First, there is the classic detached accessory dwelling unit, which can go up to 1,200 square feet. Second, there’s the attached ADU, which can measure to 50% the size of your existing home’s square footage. Third, there’s the garage-converted ADU, which can be a faster value-add for your home. Lastly, you can add or convert a second story or basement into an ADU.
We highly recommend doing a feasibility study with us before jumping into an ADU project.