Legalize an Unpermitted Orange County Garage Conversion/ADU

It should come as no surprise that there are many unpermitted Orange County garage conversions. Residents have been utilizing their additional garage space without the proper permissions for quite some time due to the high cost of housing. When discussing garage conversions in Orange County, there are numerous things to understand. 

Some homeowners have converted their garages into workout or music studios. Other individuals have created an office, man cave, recreation room, or she-shed, some without a restroom. Obviously, some people have converted their garage into a full Accessory Dwelling Unit with a bathroom, kitchen, etc. These are either family homes or rental properties. Check out our blog for additional information about Garage Conversions.

Here at GreatBuildz, a free service that connects homeowners in Los Angeles, Orange County, Ventura or San Diego with reliable general contractors, we get inquiries every day about unpermitted Orange County garage conversions and how to legalize them – here are some tips to get you started.

What You Need to Know About Your Unpermitted Orange County Garage Conversion

Many of these unlawful garage conversions have been built in Orange County and the surrounding areas without the required permits, and now a significant number of these homeowners are considering legalizing their units. Now that new ADU rules have gone into effect on January 1, 2020, the state and cities are urging people to legalize their unpermitted garage conversions in Orange County, and some have given a grace period to do so without incurring fines or other penalties.

People are beginning to recognize that it is more cost-effective to legalize their unpermitted garage space than to continue “hiding” it. Unlike unpermitted space, a legal ADU can be rented to a tenant without trouble and clearly increases the property’s value at the time of sale.

Unpermitted garage conversion orange county

There is positive news regarding the legalization of unpermitted garage conversions in Orange County. In most instances, the garage is “eligible” for conversion into an ADU. Assuming your garage was approved/permitted when it was constructed, you should be able to convert it into an ADU (for a detached garage) and Junior ADU or JADU (for a smaller ADU) (for an attached garage).

Even if your garage does not meet the current property line setback regulations, it should be grandfathered in.

There will be a few exceptions, such as a hillside or high-fire zones, therefore it is essential to confirm that your property qualifies by contacting a skilled architect or the city’s building or planning department. When turning your garage into an ADU, you should not be required to add additional parking on your property, thanks to the newest ADU regulations. Even if your city requires parking, you should be able to fulfill that requirement just by having a driveway.

Let’s talk about the measures necessary to legalize your unpermitted garage. As mentioned previously, the first step is to validate that your garage is eligible. After confirming this, the next step is to hire an architect/designer to draft the blueprints and meet with at least one ADU contractor to discuss rough costs and scope.

Develop a Set of Plans

Unpermitted adu planning

The city mandates you to create a set of garage conversion blueprints in Orange County. These designs illustrate that your garage conversion conforms to current construction requirements and regulations. Therefore, the plans will incorporate structural and framing details, windows and walls, energy efficiency (title 24), and additional notes.

An architect will measure your area and design these blueprints with the assistance of a structural engineer, if necessary. This is the full plan set that will be presented to the city’s building department for a permit. These plans will likely cost between $4,000 and $12,000. ADU Contractors can also assist in this design process.

Consult With an ADU Contractor Regarding Your Orange County Garage Conversion

meeting with ADU contractor

Additionally, you should meet with an ADU contractor. The ADU contractor can examine your garage and provide you with information regarding the associated expenses, the construction procedures, and the potential “unknowns.” Depending on how properly or poorly your unpermitted garage conversion was constructed, there may be a significant variation in legalization expenses.

For example, do the walls contain insulation? Is the current sewer line sufficient? Are the foundation footings sufficiently deep? Will structural or framing modifications be necessary?

A competent general contractor can assess the possibility and cost of these unknowns based on what they see. It is vital to know this so that you can properly budget to legalize your ADU and avoid being surprised once you design plans and obtain a permit.

Submit Your Plans

Once you have a rough cost estimate and a complete set of blueprints, the following step is to submit them to the city’s building department. In fewer than sixty days, you should acquire a building permit (or corrections to make to your plans).

While your designs are undergoing plan review, you can give them and any additional scope of work to multiple garage conversion contractors so they can offer you precise cost quotes.

After selecting and signing a contract with your preferred garage conversion contractor, you are ready to begin building.

Commence Construction on Your Orange County Garage Conversion

ADU construction

Your ADU builder will request a preliminary city inspection at the onset of construction. The city inspector will want to see how your unpermitted garage conversion compares to your plans (and the current building code).  You may need the contractor to remove sections of drywall so that the inspector can “see inside” the walls.

He or she will inspect the framing, electrical, plumbing, insulation, etc. for suitability. He may also request to see the foundation footing depth. Based on what he or she observes, the inspector will offer a list of “corrections” that your contractor must implement before proceeding. As noted above, these “unknowns” may be minor or significant, depending on the quality of the original build.

Depending on the current state and quality of the ADU, expenses can vary dramatically. To give you an idea, a brand-new garage conversion in Orange County costs between $90,000 and $120,000. This figure covers adding a kitchen, bathroom, appliances, walls, windows, flooring, HVAC, plumbing, electricity, structural framework, etc. to a standard garage.

Presumably, when legalizing a garage conversion, a portion of this work has already been completed. Depending on the scope of the required work, the construction expenses to legalize your old garage conversion will likely range between $30,000 and $80,000.

How to Locate the Best ADU Contractor for Your Orange County Garage Conversion

adu contractor

It is advisable to seek out local, licensed General Contractors. No other professionals are qualified or equipped to perform this type of construction, and it would be a mistake to hire an unlicensed contractor or handyman. Verify that any contractors you approach have experience with illegal or unpermitted ADUs.

You’ll want to employ a contractor who has completed a similar project in the past and is fully aware of the potential issues/pitfalls.

There are various additional items that should be considered when selecting an ADU contractor:

  • Verify on the Contractors State License Board website that a contractor’s license is active, has no disciplinary actions, and has Workers’ Compensation insurance (assuming the GC has employees).
  • Verify if they have insurance and obtain a copy of their insurance certificate.
  • Request at least three references from your contractor.
  • Read their internet reviews on Google and other contractor review websites.

Check out my blog for more information on how to discover and evaluate an ADU contractor: 10 Guidelines for Employing an ADU Contractor

Compare the Bids of Your Contractors

evaluating contrator bids

The following stage is to compare contractor proposals. Not only should you compare prices, but also the extent of the scope. Contractors can submit bids that vary widely. When you meet with three distinct builders, it is likely that they will hear three different things. Therefore, it is essential to examine and compare all proposals for consistency.

Why Legalize an Unpermitted ADU?

It’s clear that legalizing an unpermitted ADU requires a reasonable amount of time, work, and money. However, many homeowners may find the investment worthwhile. Once you legalize an unpermitted ADU, it significantly increases the value of your home because it becomes a recognized part of your property.

In addition, after legalizing an unpermitted ADU, you may legally rent it to a tenant and collect rent. Remember to call your insurance agent and inform them that your new legal ADU must be added to your homeowners’ property coverage.

If you want to learn more about the costs or process of legalizing an unpermitted Orange County garage conversion or ADU project, or if you’re ready to take the next step and talk to a local contractor or designer/architect about your specific project, feel free to call one of our friendly GreatBuildz staff at 818.317.3567 or submit your project at


Check out the GreatBuildz Guide Blog for more construction tips and advice for any type of home remodeling project!

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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