Find a Garage Conversion Contractor in Orange County

You’ve probably heard about the new laws and regulations in Orange County regarding Accessory Dwelling Units and garage conversions.  A garage conversion is the most cost-effective way to create a ‘second home’ or Accessory Dwelling Unit (ADU) on your property because the basic garage structure already exists.

Most 2-car garages are usually 300-450 square feet, which is large enough for a ‘studio’ unit or small one-bedroom with both a kitchen and bathroom. Before you start, there’s a lot to know – everything from developing plans, evaluating costs, and considering various requirements, to picking a floor plan and hiring the right garage conversion contractor.

Here at GreatBuildz, a free service that personally matches homeowners in Los Angeles, Orange County, Ventura & San Diego with reliable general contractors, we talk to homeowners every day about ADU and garage conversion projects and costs – here are some key points to know.

Garage Conversion Plans

The first phase is to hire a small architecture or design firm to draw the plans with your guidance.  This is a reasonably straightforward design project, so you don’t need an expensive architecture firm – an experienced draftsperson is suitable for a project like this.

Garage conversion plan costs should range between $5,000-$12,000. You’re likely to be doing very little alteration of the exterior of the garage; just adding a front door and windows, so that makes the design reasonably basic. In addition, there shouldn’t be extensive structural changes as the exterior, load-bearing walls are in place.

But, be aware that the architect/designer will still need to involve a structural engineer in the design to add any structural elements necessary. Most of the design work involves the interior layout. As you can see in the plan below, this design has a ‘great room’ that included a living area, kitchen, and dining area.

This left enough room for a small bedroom with a closet and a basic full bathroom. A small bedroom would ideally be a minimum of 10’x10’ and a full bathroom is a minimum of 5’x8’. (A GreatBuildz staff can recommend a reasonably priced plan designer if you need one)  

Garage Conversion floor plan great room

Once you’re happy with your plans, the architect/designer will submit the plans to the city building department for a plan check. This approval might take anywhere from 2 weeks to 2 months, depending on the city’s backlog.  During that time, you can start discussing your plans with several garage conversion contractors and have them provide you with cost estimates.

Although you can act as your own ‘general contractor’ and hire sub-contractors to complete such a project, I highly recommend against it.  It is likely to be cheaper in price, but much, much greater in time and headaches.  Also, it’s not something you should consider unless you know of good subcontractors for all the trades involved (ie. plumber, electrician, drywall, tile, stucco, etc).  

How To Find A Garage Conversion Contractor

Garage Conversion Contractor Presentation

Let me give a couple of suggestions for finding the right garage conversion contractor for your needs.  It’s best to search for only local, licensed General Contractors.  No other contractors are qualified or equipped to do this sort of project, and using an unlicensed contractor or handyman would be a mistake.

For any garage conversion contractor you contact, always confirm they have experience with 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 use in selecting a garage conversion contractor, including:

  • 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 that it has Workers Compensation insurance associated with it (assuming the GC has employees). 
  • Make sure your garage conversion contractor is insured and get a copy of their insurance certificate.
  • Ask your garage conversion contractor for at least three references you can call.
  • Read their reviews online on Google & other Social Media sites.  

Related: Garage Conversion and ADU Insurance Info for 2021

(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, trustworthy contractors who are experienced with garage conversions and ADUs. For more info, visit or call 818.317.3567 today)

Garage Conversion Requirements: It’s All In The Details

Your architect/designer’s plans will give all potential contractors a majority of the information they need to bid on the job, but it won’t include 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. For HVAC, do you want a full-size HVAC system in your home or do you want a small ‘ductless’ unit that is cheaper but serves a smaller area? For electrical, how many outlets, lights, & switches do you need and where do you want them? Also, you’ll need to discuss with your garage conversion contractor what kind of electrical panel you’ll need for the ADU.

Garage Conversion Contractor Planning

In addition to these ‘major’ decisions, you’ll also need to decide if you need other items included in your garage conversion – so there are many more questions to ask yourself…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 in the yard? 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 that needs to be repaired? Do you want a bathtub or just a shower? What will your kitchen design look like? Are any appliances included in the bid?

And finally, the more detail you can give on your desired finish materials, the more accurate your contractor’s price can be unless you will be buying all of these yourself.

Can you 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 pay the difference if you choose materials that are more expensive than the allowance in the bid.  

Garage Conversion Cost-Saving Tips

There are several simple ways to save money on your garage conversion. To reduce the number of plumbing lines, ensure that all of your plumbing fixtures (bathroom and kitchen) are positioned on one wall. Because tile is expensive and time-consuming to install, another strategy is to limit its use. Use a fiberglass one-piece shower tub and surround combo instead of shower tile in the bathroom, for instance. Finally, consider installing LVP (luxury vinyl plank) flooring throughout the unit, including the bathroom, so that you do not need to tile the floor.

Comparing Garage Conversion Contractor Bids

Garage Conversion Contractor Handshake

The next step is to compare your contractors’ bids. Be careful not to just look at the price, but also carefully compare the scope of work that’s included. Bids can be very inconsistent among each garage conversion contractor. Let’s face it, when you meet with three different people, they may hear three different things (and maybe you even forgot to mention something in each case). But, that’s why it’s important to carefully review and compare all bids for consistency.

In a perfect world, you’d create your own ‘master list’ of all the items that should be in the estimates that you can use to compare all bids against.  If any potential garage conversion contractor bid is missing something or is unclear, make sure to 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 an Orange County garage conversion cost to be in the $60,000-$120,000 range. There are several ways you can save on garage conversion costs: check out our Top 5 Cost-Saving Tips for ADUs.

Related: 10 Best Tips for Finding an ADU Contractor in LA

A few more things to consider for an ADU Garage Conversion

Garage Conversion Contractor Bids

Sewer line: The city will most likely require you to run a new sewer line from your ADU to the existing sewer lateral in your front yard.  I strongly suggest you 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 line through a dirt area is much cheaper than running it under a concrete driveway; not to mention that a section of your driveway wouldn’t need to be ripped up and patched.

DWP/Edison powerlines: If you have DWP or Edison power lines at the back of your property, and your garage is currently under the powerlines, you may not be allowed to convert it to an ADU. I suggest inquiring with DWP or Edison first about relocating the line over your garage; it’s 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 preclude you from converting it to an ADU. You should speak to your architect, contractor, or city building department about this.

Sale/rental of your garage conversion ADU: You can rent your ADU to a tenant, even if you don’t live on the property (You can rent out both your main house and ADU).  You cannot sell your ADU separately from your main house.

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 garage to an ADU regardless of its location (even if it’s within the 4-foot setback requirements), any addition you want to 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). This applies to a single-story addition to the garage or a second-story built over the 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 more about this).


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 in 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:


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Garage Conversion Guidelines For Every City in Orange County

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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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