What You Need To Know About Ventura County Garage Conversions In 2024

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.

Ventura County ADU

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 first step is to hire a local Ventura County architecture or design firm to draw the plans with your input. This is a reasonably simple design project, so you don’t need an expensive architect. Garage conversion plan costs should range between $8,000-$12,000. You’re likely to be doing very little alteration of the garage exterior: just adding a front door and windows, and this makes your plans reasonably basic.

There shouldn’t be major structural work as the exterior, load-bearing walls are staying in place. But, the architect will still need to involve a structural engineer to add any structural elements that are required.

The majority of the design work involves the interior layout. In the plan image below, this design has a ‘great room’ that includes a living area, kitchen, and eating area. The remainder of the garage became a small bedroom with two closets and a basic full bathroom. A small bedroom would generally be a minimum of 10’x10’ and a full bathroom with a shower is a minimum of 5’x8’. (A GreatBuildz staff can recommend a reasonably priced architect or plan designer if you need one)  

Ventura County Garage Conversion Floor Plan

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

Ventura County Garage Conversion Contractor Worksite

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

Ventura County Garage Conversion Project Planning

Your architect/designer’s plans provide all potential contractors with most of the information they need to bid on the job, but it doesn’t have everything.  Many cities don’t require your plans to include details about electrical, plumbing, HVAC, etc., so you’ll need to provide your garage conversion contractor with details of what you want.

For plumbing, you’ll need to decide where you want your water heater and if it’s a tank or tankless. With HVAC, do you want a full-size HVAC system like in your home or do you want a small ‘ductless’ unit that is cheaper, but serves a small area? For electrical, you’ll need to decide how many outlets, lights, & switches you’ll need and where you’ll you want them. Also, you’ll need to discuss with your garage conversion contractor the size of the electrical panel you’ll need for the ADU.

In addition to these significant decisions, you’ll also have to let them know if you need other items included in your project.

Do you need the garage to be re-roofed? Do you need any concrete work like a footpath, driveway, front stoop, etc?

Do you need any new fencing or landscape work? Do you want flat or vaulted ceilings?

Will you be painting the exterior of the garage conversion? Is there any termite or water damage in the existing garage wood that needs to be replaced? Do you want a bathtub or just a shower? What will your kitchen cabinets look like? Are appliances included in the bid?

Finally, the more detail you can provide about your desired finish materials, the more accurate your contractor’s estimate can be, unless you plan on buying all of the materials yourself. Ideally, you will pick out your tile, flooring, kitchen cabinets, lights, faucets, doors, windows, etc. in advance. If not, your garage conversion contractor will likely give you a material ‘allowance’ for each material in their bid; in which case you would have to pay the difference if you choose materials that are more expensive than the allowance.  

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

Ventura County Garage Conversion Contractor Comparing 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

Ventura County Garage Conversion Survey

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 2024, 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, meaning the homeowner must live in either the main house or the JADU as their primary residence. Learn more about JADUs in my blog.

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




  • Simi Valley


  • Moorpark



  • Camarillo



  • Oxnard



  • Ventura  



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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