Accessory Dwelling Unit Guide for Ventura County – Essential New Regulations For 2024

[Updated January 2024]

An ADU, otherwise known as an accessory dwelling unit or additional dwelling unit, is a second structure on a residential lot in addition to the main house. And these guys are having a moment. Thanks to recent relaxed regulations by both cities and the state, the allure of ADUs has skyrocketed, making it a hot topic among homeowners. The once stringent rules have given way to a surge in interest, with homeowners exploring the possibilities of building ADUs in their backyards or transforming garages into stylish living spaces. It’s a housing revolution, bringing flexibility and creativity to home design, and homeowners are seizing the opportunity to enhance their properties with these versatile, additional living spaces.

Ventura County Accessory Dwelling Unit

Here at GreatBuildz, a free service that connects homeowners in Los Angeles, Orange County, Ventura & San Diego with reliable ADU contractors, we get inquiries every day about accessory dwelling unit projects – here are some key points you need to know.

To help you learn more about ADUs and decide whether or not to build one, this blog posts discuss the rules and guidelines that have recently changed to make accessory dwelling units much more viable for many homeowners. We’ll start with state guidelines before drilling down into specific rules for Ventura County. Let’s go!  

Ventura County ADU and Garage Conversion Guide – Key Takeaways

  • Recent changes allow larger ADUs applicable to all single-family properties without a minimum lot size. Multi-family properties, including duplexes and apartments, are also eligible. Setbacks from property lines are reduced, and impact fees may be waived in some cases. Rental to tenants no longer requires owner-occupancy, and HOA/CC&Rs cannot restrict ADU construction.
  • The revised guidelines allow for zero parking in many cases, especially near transit options, offering flexibility in ADU design and construction.
  • Many ADU projects no longer require discretionary approval, streamlining the process. Submitting plans to the building department and undergoing the plan check process is sufficient in numerous cases.
  • AB 1033 permits the separate sale of ADUs from the primary residence, though practical challenges may limit its impact. AB 976 eliminates the deadline for owner-occupancy restrictions, fostering greater flexibility in ADU rentals. AB 434 mandates cities to develop pre-approved ADU plans by 2025, aiming to expedite planning and construction.
  • Homeowners can choose between garage conversions and new builds, each with varying costs. Garage conversions range from $90,000 to $120,000, while new ADUs can cost $100,000 to $400,000. Financing options include personal savings, home equity loans, construction loans, or home renovation loans from companies like RenoFi, Lightstream, or SoFi.
  • The ADU construction process involves meeting with contractors, developing architectural plans, obtaining necessary approvals, selecting a contractor, and beginning construction. Garage conversions typically take 3-6 months, while new builds may take 6-9 months.
  • Prioritize local, licensed general contractors with ADU experience. Verify their license and insurance, check references, and review online feedback. Look for contractors with a solid track record and excellent references, as well as a valid and current contractor’s license.

California State Accessory Dwelling Unit Changes

Changes recently made in California to ADU regulations include:

  • Increase in maximum accessory dwelling unit size allowed
  • Allowed on all single-family properties, with no minimum lot size requirement
  • Allowed on multi-family properties, including duplex, triplex, fourplex, and apartments
  • A greater variety of types of accessory dwelling units allowed
  • Reduced setbacks from rear/side property lines
  • Impact fees (sewer fees, school fees, etc) are being waived in some cases
  • Allows accessory dwelling units to be rented to a tenant without owner-occupancy requirements (in most cases)
  • HOA/CC&Rs cannot restrict building accessory dwelling units
  • Parking –The guideline now allows zero parking in many cases for the accessory dwelling unit, as long as it’s near transit.
  • City approvals: Accessory dwelling units now, in many cases, don’t require any ‘discretionary’ approval, meaning that you don’t need approvals from the city planning department, neighbors, planning boards, etc, as long as you meet the established guidelines. So, getting the right to build an accessory dwelling unit is just a matter of submitting plans to the building department and going through the plan check process to obtain a building permit. But, start by speaking with the staff at your Planning Department to confirm there are no constraints to building an ADU in your city.

Ventura County ADU Guidelines

Each city in Ventura County is enacting its own guidelines that generally follow the lead of the state rules but may have its own specific differences. Below are resources on Ventura County and various city’s accessory dwelling unit guidelines:

County of Ventura Accessory Dwelling Unit Guidelines

Thousand Oaks ADU Regulations

Simi Valley Accessory Dwelling Unit Guidelines

Moorpark Accessory Dwelling Unit Process and Submittal Checklist

Camarillo ADU and Garage Conversion Rules

Oxnard ADU Regulations

Ventura City ADU Laws

New ADU Laws for 2024

AB 1033

The October 2023 passage of AB 1033 has generated a great deal of interest in the news media. This law permits the sale of an ADU separately from the primary residence on the property, which was never permitted in the past. However, there are a few significant obstacles worth mentioning that will likely limit the actual impact of this law in practice.

First, the law states that a municipality or city may adopt an ordinance allowing the individual sale of ADUs, but it does not mandate that they do so. So, presumably, there will be cities that adopt such an ordinance, but there will also be cities that do not want this law in their jurisdiction.

In addition, the procedure of selling an ADU separately from the primary residence is not simple. It necessitates converting the property into a condominium, which is the legal process of dividing ownership between the units (in this instance, the primary residence and the ADU). This method is comparable to that used by condo building developers to divide ownership and sell individual units.

The procedure is not straightforward and requires a great deal of skill, money, and time. Initially, you retain an attorney to draft the various condominium documents (Bylaws, CC&Rs, Declarations, etc.) and a surveyor to construct a condo plat map that outlines the ownership boundaries. ( The next step is to submit these to the California Department of Real Estate and await approval. After approval, you will be required to record these documents with the County Recorder.

You may now sell this ADU “condo” on your property, but bear in mind that you have now created a HOA (homeowners association) between your two properties, which must manage the common property. You have also significantly decreased the value of your remaining property by converting it from a single-family residence to a condominium.

Lastly, bear in mind that if you have a mortgage on your property, you will need approval from your lender to sell off a portion of their loan security (i.e., the ADU and a portion of the property). It is unlikely that they will make this experience seamless.

[Read AD 1033]

AB 976

Prior to the implementation of this law, California cities and municipalities were prohibited from imposing “owner occupancy” restrictions on all ADUs permitted between January 1, 2020 and January 1, 2025. This permitted property owners to rent out their ADUs. When this deadline expires in 2025, however, cities could theoretically reinstate owner-occupancy restrictions on ADUs, thereby reducing the supply of rental housing.

AB 976 eliminates the deadline restriction by prohibiting cities from imposing any owner-occupancy restrictions on ADUs in the future. It maintains, however, the local government’s ability to restrict rentals of less than 30 days.

[Read AB 976]

AB 434

AB 434 mandates that by January 1, 2025, all California cities and municipalities must develop a pre-approved ADU plan program. It requires these cities to accept plans for submission in order for them to be “pre-approved” for future use by other owners/applicants. It also stipulates that these plans must be published on the city’s website. They may also post and “pre-approve” approved plans from other cities or regions of the state.

Although the law is silent on the matter, it is assumed that architects will have their designed plans “pre-approved” and published on the city’s website. Since the architect owns the plans and has the rights to their design, anyone who wishes to use them will likely be required to pay a fee.

In addition, even pre-approved plans are not 100 percent comprehensive, as each property is somewhat unique and the plans may need to be slightly modified or supplemented to accommodate each circumstance. In addition, the new law permits the city to continue charging the same fee for the ‘plan check’ procedure with pre-approved plans as with other sets of plans.

The law aims to further expedite the planning and construction of ADUs in California. Due to the uniqueness of many property situations, not all property owners will be able to use pre-approved plans. However, in many cases, a homeowner who wishes to construct an ADU may locate a suitable plan on the city’s website for pre-approved ADU plans, thereby saving ‘some’ time and money.

[Read AB 434]

What kind of accessory dwelling units are there?

The two primary options are either building a new, free-standing unit in the backyard or converting an existing garage to an accessory dwelling unit. A garage conversion is the most cost-effective option because the basic structure already exists. The downside is the limitation in size – most 2-car garages are only 300-400 square feet. This is still enough space for a ‘studio’ unit or a small 1-bedroom, with both a kitchen and a bathroom.

A newly built accessory dwelling unit can take many forms. It can be attached to the existing family home, attached to a garage in the back of your property, or detached completely. It can be one or two stories, with a maximum height of 25 feet.

In most cases, it must be in the backyard and not in front of your main house. A new detached accessory unit can be a maximum of 1,200 square feet, while an addition attached to an existing home is limited to the lesser of either 1,200 square feet or 50% of the size of the current home. A 400-600sf accessory dwelling unit is ideal for a one-bedroom plan and a 600-1200sf structure is enough to be one or two stories, with up to three bedrooms and two or three baths.

Why build an ADU on your property?

Many homeowners are excited about the modified guidelines and are now exploring the possibility of building an ADU or ‘granny flat’ on their property, but why? It comes down to two things: their ability to add living space to their property in a simplified manner and the tremendous variety of potential uses of an accessory dwelling unit.

Adding space to an existing house in the past meant building an ‘addition’ or second story, which was challenging. Not only was it often costly, time-consuming, and usually required considerable changes to the existing layout of the home, but it also meant living through the dust and mess of construction in your home. A second-story addition is an even more significant project, which will invariably require the home occupants to move out during construction.

An accessory dwelling unit solves many of these problems and allows for a lot of flexibility. Some homeowners are building them as extra space (an office or guest house), a music or yoga studio, a mancave or she-shed, or a dwelling for their retired parents or grown children. Beyond that, it’s also possible for homeowners to use them as rental units for additional income. I’ve also heard from several retired homeowners planning to build an accessory dwelling unit so they can move into it (as a way to downsize) and rent their primary home as a source of retirement income. That’s an impressive idea.

Ventura County Accessory Dwelling Unit Floor Plan

Future resale value

Considering the impact of ADUs on future resale value is a crucial aspect for homeowners embarking on such projects. ADUs, when strategically designed and well-executed, have the potential to enhance property value and market appeal. The additional living space and versatility they offer cater to diverse buyer preferences, making the property more attractive.

Buyers increasingly appreciate the flexibility provided by ADUs, whether for accommodating extended family, generating rental income, or having a dedicated home office or studio. As the demand for multi-generational living and income-generating opportunities rises, homes with ADUs become sought after in the real estate market.

To maximize future resale value, homeowners should ensure the ADU aligns with local building codes and zoning regulations. Quality construction and thoughtful design that integrates seamlessly with the existing property can positively influence appraisal values. Highlighting the ADU’s energy-efficient features or smart home technology during resale can also add appeal.

Moreover, emphasizing the potential for rental income or a separate living space can attract a broader range of buyers. As real estate trends evolve, the flexibility and functionality offered by well-planned ADUs position properties for increased market competitiveness and potential profit upon resale. Homeowners should consider these factors when investing in ADUs to ensure a wise and lucrative enhancement to their property.

How much does an accessory dwelling unit cost?

An accessory dwelling unit will vary in cost depending on the options and size you choose. As I discussed, the most cost-effective option is to convert an existing detached garage to an accessory dwelling unit.

Since the major components already exist in a garage, this build-out requires items such as constructing the fourth wall (where the garage door is currently), adding interior walls, a kitchen, bathroom, flooring, etc; adding doors and windows, plumbing, electrical, HVAC, insulation, and a new sewer line that connects to the sewer lateral on the property.

The construction cost for an ADU garage conversion usually ranges $90,000-$120,000 depending on location and the homeowner’s requirements. Costs will go up if the garage has a lot of deferred maintenance, such as a cracked floor or leaky roof. Costs to construct a brand new ADU will vary considerably based on size, the number of stories, location, access, etc., but will generally range from $100,000 to $400,000. A good rule of thumb is to assume $300-$400 per square foot – the bigger the space, the lower the cost per square foot. If you’re considering ‘building up’ with a 2-story (or second-story) accessory dwelling unit, costs will go up as well. Check out our ADU scope checklist to determine what items need to be included in your ADU project budget,

See More: 5 Best ADU Cost-Saving Tips

How do I pay for an accessory dwelling unit?

There are multiple ways to finance an accessory dwelling unit project. Obviously, homeowners can pay for it from their own savings. Or they can finance this project by taking out a home equity line of credit, getting a construction loan from their bank, or using a home renovation loan that offers a quick processing timeline but does come with a higher interest rate from a company like RenoFi, Lightstream, or SoFi.

What is the process of building an accessory dwelling unit?

This process begins with the homeowner meeting one or more experienced ADU contractors, who will come to the home to discuss the project and provide some guidance about the constraints, size, design, estimated costs, etc. Once the owner and contractor decide on the basic parameters, either one can bring in an architect or a plan designer to start the architectural plans. Garage conversion or ADU plans should cost between $7000 – $20,000 depending on complexity.

Local building codes continue to change over the years, so make sure your architect or designer has experience with ADUs in your specific city or area. Ask them if there are any newer building requirements in your area, such as solar panels, fire sprinklers, or other energy-efficient guidelines.

Once the plans are complete and approved by the owner, contractors can prepare a detailed estimate/bid. Next, the owner will choose their desired contractor and sign an agreement for the work. Either the architect or contractor can submit the plan set to the building department for plan check and coordinate the process until a building permit is issued. Finally, construction can start.

How long does it take to build an ADU?

The timing depends on whether you are doing a garage conversion versus a new construction project. For a garage conversion, expect the entire process to take 3-6 months, which includes the timing to design the plans, the turnaround time for the city to do the plan check, and finally, the construction process – which often takes about 2-3 months. A new ADU will take longer for the construction process, so you can expect the whole process to take 6-9 months, with the construction phase taking 3-6 months.

Finding the right team – How do I hire a good ADU contractor?

When looking to build an ADU or even starting to research the idea, I suggest looking for only local, licensed general contractors. No other contractors are qualified to do this sort of major construction, and using an unlicensed contractor or handyman would be a big risk. Any qualified contractor should have both General Liability and Workers’ Compensation insurance as well as a bond.

Any contractors you speak with, always confirm they have experience with ADU projects. It is best to hire a contractor who’s built additions and garage conversions and knows the potential problems and solutions. There are several other criteria you should use in choosing a contractor, not including their price.

Watch More: GreatBuildz Co-Founder Paul Dashevsky discusses what to look for in a good general contractor

Ventura County Accessory Dwelling Unit

What to look for in a reliable contractor

Here are some things to search for when choosing an ADU contractor.

    • Valid and current contractor’s license: It’s extremely important to check a license on the Contractors State License Board website to verify it’s active, there are no disciplinary issues, and it has Workers’ Compensation insurance associated with it (assuming the GC has employees).
    • Insurance: Always get a copy of the Contractor’s insurance certificate and make sure that it isn’t expired. It could be a good idea to call the insurance broker, just to be sure. There have been cases where uninsured contractors have ‘Photoshopped’ their insurance papers to trick homeowners, so you can never be too careful. All quality, reputable ADU contractors will carry both Liability and Workers’ Compensation Insurance. Hiring a contractor with sufficient insurance will alleviate the financial stress of any potential issues that arise during the project. Pro-tip: Contact your own homeowner’s insurance agent before you start your project to confirm if your existing coverage is sufficient during and after the ADU’s construction. If you plan to rent the ADU to tenants, you may need a supplemental ‘landlord policy’.
    • Excellent references: Ask all contractors for at least three references you can call. It’s important to call and ask these people about their experience and satisfaction with the quality of the contractor’s work if you can even get some pictures of the work, even better.
    • Glowing online reviews: It’s a good idea to do a Google/Yelp/Social Media search of the contractor to check for any major red flags. Read all the reviews you can find about their business, and don’t be afraid to address what you found with the contractor if anything is surprising. Bear in mind that just because they have hundreds of positive reviews, it may not necessarily mean they are the best, as there are more and more fake reviews out there. Additionally, some of the best contractors work primarily off personal referrals and thus haven’t had much of a need to develop a website or bolster their online presence.

I’ve written a detailed article specifically on the topic of hiring an ADU contractor. If you’re currently in the process, take a look at it here: 

At GreatBuildz, we take contractor screening seriously. We take all the steps above, in addition to running a background/financial check and requiring contractors to sign our 20-point Code of Conduct. Feel free to call our free service and our friendly staff will match you with several fully vetted, honest contractors in Los Angeles, Orange County, Ventura & San Diego who are experienced with ADUs. For more info, visit or call 818.317.3567 today.

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