A garage conversion in Ventura County typically costs $120,000 to $150,000 to create a legal ADU with a kitchen, bathroom, and separate entrance. California law makes them straightforward: no replacement parking, a 60-day approval requirement, and no impact fees under 750 square feet. Here’s what to know about converting a garage in Ventura County.
You’ve probably heard about the new laws and regulations in Ventura County and surrounding areas regarding accessory dwelling units and garage conversions. A garage conversion is the cheapest way to create a ‘second unit’ or ADU on your property because the basic garage shell already exists.
Most 2-car garages are approximately 300-450 square feet, which is big enough for a ‘studio’ unit and sometimes a small one-bedroom, both would include a kitchen and bathroom.
Before you begin, there’s a lot to know – everything from creating architectural plans, budgeting costs, and researching the rules & requirements, to picking a floor plan and hiring a Ventura County garage conversion contractor.
Here at GreatBuildz, a free service that personally matches homeowners in Los Angeles, Orange County, Ventura & San Diego with reliable garage conversion contractors, we talk to homeowners every day about Accessory Dwelling Units and garage conversion projects and costs – here are some key points you need to know.
Conejo Valley & Ventura County Garage Conversions – Process and Costs
Ventura County Garage Conversion Plans
The 1st Step is to Hire a Local Architect or Designer
Start by hiring a local Ventura County architect or design firm to create your garage conversion plans. Since this is a fairly simple project, you don’t need a high-end architect. Plan design costs should typically fall between $8,000–$12,000.
Because you’ll likely only be making small changes to the exterior, such as adding a front door and a few windows, your plans will remain relatively straightforward.
Minimal Structural Changes Needed
There shouldn’t be any major structural work involved, as the garage’s load-bearing exterior walls will stay in place. However, your architect will still need to consult a structural engineer to ensure any necessary structural components are properly included.
Focus on Interior Layout
Most of the design effort will go into the interior. In the example plan below, the layout features:
- A great room that combines the living area, kitchen, and dining space
- A small bedroom with two closets
- A basic full bathroom with a shower
As a guide:
- A small bedroom should be at least 10’x10’
- A full bathroom with a shower should be at least 5’x8’
Need help finding someone? A GreatBuildz team member can recommend a reliable and reasonably priced architect or plan designer.
Once you’re satisfied with the architect’s plan, he/she will submit the plans to the city building department for plan check. This process might take anywhere from 2 weeks to 3 months, depending on the city’s backlog.
During this time, you should start discussing your plans with a few garage conversion contractors and have them start bidding on the plans to provide you with cost estimates. Although you could, in theory, act as your own ‘general contractor’ and hire out sub-contractors to complete such a project, I don’t recommend it.
Although it might seem cheaper in price, the process will be much greater in time and headaches. Also, it’s not something you should do unless you know good subcontractors for ALL the trades involved (ie. plumber, electrician, drywall, tile, stucco, etc).
How To Find a Ventura County Garage Conversion Contractor
Below are a couple of suggestions for finding the right contractor for your garage conversion.
It’s best to search for only local (Ventura County or Conejo Valley), licensed General Contractors. No other types of contractors are qualified to do this sort of project, and using an unlicensed contractor or handyman is a big mistake. For any contractors you speak with, always make sure they have experience with garage conversions or ADUs. It is best to hire a contractor who’s built garage conversions or Accessory Dwelling Units in the past and knows the potential issues/pitfalls.
There are several other criteria you should consider before hiring a contractor. Check for a valid contractor’s license on the Contractors State License Board website and confirm it is active, there are no disciplinary issues, and it has Workers’ Compensation Insurance associated with it (assuming the GC has employees).
Make sure your garage conversion contractor is fully insured and get a copy of their insurance certificate (and ask them to make you ‘additional insured’). It’s important that you ask your contractor for at least three references…and call them. Check their reviews online on Google & other Social Media sites too.
(At GreatBuildz, we take contractor screening very 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. You can call our free, friendly service to be connected to several fully vetted, reliable Ventura County garage conversion contractors. For more info, visit www.GreatBuildz.com or call 818.317.3567 today)
Garage Conversion Requirements: It’s All In The Details
What Plans Include, and What They Don’t
Your architect or designer’s plans will give contractors most of what they need to bid on your garage conversion, but not everything. Many cities don’t require detailed plans for plumbing, electrical, or HVAC, so you’ll need to work directly with your contractor to fill in the gaps.
Key Decisions You’ll Need to Make
You’ll need to provide input on the following systems:
- Plumbing
- Where do you want the water heater?
- Will it be tankless or a traditional tank?
- HVAC (Heating & Cooling)
- Do you prefer a full-size system like in your home?
- Or a ductless mini-split unit, which is cheaper but serves a smaller area?
- Electrical
- How many outlets, lights, and switches do you need, and where?
- What size electrical panel will the ADU require?
Other Features to Consider
Your contractor will also need to know whether to include the following in the project:
- Roofing: Does the garage need to be re-roofed?
- Concrete work: Do you want a new footpath, driveway, or front stoop?
- Fencing and landscaping: Are any new features needed?
- Ceilings: Do you want flat or vaulted ceilings?
- Exterior painting: Will the outside of the garage be painted?
- Repairs: Is there any termite or water damage that needs to be fixed?
Interior Details
- Bathroom: Do you want a bathtub or just a shower?
- Kitchen: What will the cabinets look like? Are appliances included in the contractor’s bid?
Finish Materials
The more detailed you are about finish materials, the more accurate your contractor’s estimate will be. If you already know what you want, like tile, flooring, lighting, faucets, cabinets, doors, and windows, share that information upfront.
Otherwise, your contractor will likely include a material ‘allowance’ in their bid. Keep in mind that if you select items more expensive than the allowance, you’ll need to pay the difference. You can also choose to buy the materials yourselfif you prefer.
Garage Conversion Cost Saving Tips
There are a few easy ways to save costs on your garage conversion. One way is to make sure all the plumbing you need (your bathroom and kitchen) are located on one wall…to keep the plumbing pipes to a minimum. Another way is to limit the use of tile because it is expensive and time-consuming to install.
For example, in the bathroom, use a fiberglass one-piece shower tub and surround instead of shower tile. And you might consider using LVP (luxury vinyl plank) flooring throughout the unit including in the bathroom, so you don’t have to tile the bathroom floor.
Comparing Garage Conversion Contractor Bids
The next step is to compare the contractors’ bids.
Be careful not to just look at price estimates, but also carefully compare the scope of work and material that’s included. Bids can be very inconsistent among contractors. Let’s face it, when you meet with three different contractors, they may hear three different things (and maybe you even forgot to mention something in each case).
That’s why it’s important to carefully review and compare all bids to each other. In a perfect scenario, you’d create your own ‘master scope list’ of all the items that should be in the estimates that you can use to compare all bids against.
If any contractor’s bid is missing something or unclear, let them know so they can revise the bid so that all your estimates are ‘apples to apples.’ Depending on your specific situation, you can expect a Ventura County garage conversion to cost somewhere in the $90,000-$120,000 range (and similar for Conejo Valley).
For a few ways you can save on garage conversion costs, check out our Top 5 Cost-Saving Tips for ADUs. Also, involving your contractor in reviewing the plans while the architect is developing them is a good idea because he/she might have some cost-saving input.
A few more things to consider for a Ventura County Garage Conversion
Sewer line: your city will probably require you to run a new sewer line from your ADU to the existing sewer pipe in your front yard. You should have your contractor determine the location and depth of your existing lateral so that they know where they will need to connect your ADU sewer. Running your new sewer pipe through a dirt planter is much cheaper than running it under a concrete driveway or paved area; not to mention that a section of your driveway will need to be ripped up and patched.
DWP/Edison powerlines: If you have DWP or Edison power lines at the back or side of your property, and your garage is currently under the powerlines, you may be precluded from converting it to an ADU.
I strongly suggest inquiring with DWP or Edison first about the line over your garage; relocating it is a bit costly & time-consuming, but it’s usually possible. If your garage is very close to the power poles and powerlines, that could also be an issue. You should speak to your architect, contractor, or city building department about this and ask if you will need an ‘encroachment permit’ in your specific situation.
Sale/rental of your garage conversion ADU: You can rent your ADU to a tenant, even if you don’t live on the property (meaning you can rent both your main house and ADU). You cannot sell your ADU separately from your main house as they reside on one single legal parcel of land. Note: In 2025, there is new legislation that MAY allow the sale of an ADU separately from a main house – this is called ‘condo-ization’ under the new AB 1033 law in California. San Jose was the first city in California to integrate this regulation into their city regulations.
Building an addition to your Garage Conversion ADU: If you want to expand your garage before converting it to a living space, there are a few things to keep in mind.
Although you can convert your legally-built garage to an ADU regardless of its location (even if it’s within the 4-foot setback requirements), any addition you build must meet the latest city ADU rules. Specifically, that means any addition would have to be located at least 4 feet from your side and rear property lines (setback requirements). Usually, this will apply to a single-story addition to the garage and a second story built over the existing garage. In addition, once your garage conversion is over 500 square feet, it will have to meet additional city requirements like LID – “Low Impact Development” (ask your architect about this).
There are also new California state laws and regulations pertaining to Junior Accessory Dwelling Units (JADU). Most often, a JADU is a conversion of an existing attached garage into a separate living unit or a JADU is created by converting part of the existing house, such as a bedroom. It is limited to 500 square feet in size. It includes an efficiency kitchen, a separate entrance, and may share or have its own bathroom facilities. One distinctive feature of JADUs is the owner occupancy requirement: if the JADU shares a bathroom with the main house, the homeowner must live in either the main house or the JADU as their primary residence. Under AB 1154, a new law effective January 1, 2026, a JADU with its own bathroom is exempt from this requirement. Learn more about JADUs in my blog.
Frequently Asked Questions
How much does a garage conversion cost in Ventura County?
A garage conversion in Ventura County typically costs $120,000 to $150,000 to create a legal ADU with a kitchen, bathroom, and separate entrance. The garage’s condition, finishes, and how much plumbing and electrical work is needed determine the final price.
Do I need a permit for a garage conversion in Ventura County?
Yes. A legal conversion needs approved plans and a building permit. Under California ADU law, you are not required to replace the lost parking, and the city must approve or deny a complete application within 60 days.
Is a garage conversion worth it?
For many homeowners, yes. A converted garage ADU adds rental income or living space at a lower cost than a detached build, since the structure already exists. The main trade-off is losing garage parking and storage, so weigh how much you use the garage.
When it comes to planning and coordinating a garage conversion for your home, you shouldn’t have to go it alone – GreatBuildz can help simplify your renovation experience.
GreatBuildz is a free service that connects homeowners Los Angeles, Orange County, Ventura & San Diego with reliable, thoroughly screened garage conversion contractors and provides project support from start to finish. Call now (818.317.3567) to chat with our local team about your next renovation project or visit our website for more information: www.greatbuildz.com
Ventura County Garage Conversion & ADU resources:
- County of Ventura
https://vcrma.org/accessory-dwelling-unit-permits
- Thousand Oaks (Conejo Valley)
https://toaks.gov/index.php?section=adu
https://www.housable.com/city/thousand-oaks-ca-789967
- Simi Valley
https://www.housable.com/city/simi-valley-ca-789751
- Moorpark
https://www.housable.com/city/moorpark-ca-789342
- Camarillo
https://www.cityofcamarillo.org/Plan%20Review-ADU%20PACKET.pdf
https://www.housable.com/city/camarillo-ca-789760
- Oxnard
https://www.oxnard.org/city-department/community-development/adu-info/
https://www.housable.com/city/oxnard-ca-789295
- Ventura
https://www.housable.com/city/ventura-ca-789053
https://www.cityofventura.ca.gov/DocumentCenter/View/20385/11A
