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Building a garage conversion ADU in Los Angeles - Everything you need to know

California has seen a steady increase in garage ADU conversions over the last few years — a popular choice among LA homeowners since they can be less expensive and faster to build than new ADU construction projects.

June 30, 2023

Depending on where you live in Los Angeles, you'll need to follow multiple regulations when converting your garage into an ADU. Some of these regulations apply to all of Los Angeles, while others are specific to certain regions, such as:

In this article, we cover the must-knows of building a garage conversion ADU in Los Angeles, including the steps involved, the benefits, and the requirements. Keep reading to learn how to obtain the necessary permits for your project and the potential pricing differences you may encounter depending on your jurisdiction.Before we get into the specifics, here are some of the benefits of converting your garage into an ADU.What are the benefits of building a garage conversion ADU?Garage to ADU conversions are very popular in LA, and they have a few advantages over other ADU types:

  1. They can be less expensive
    • If your existing garage is in good condition and requires little to no fixing up, then a garage conversion ADU can be less expensive than new projects. Conversions that make use of existing structures in good condition can have lower construction costs — and construction work adds up to 90% of the total cost of your project.
  2. They save space
    • When you’re working with existing square footage and an existing building footprint, you often don’t have to worry too much about additional setback requirements. A garage conversion can also help you preserve space in your backyard.
  3. They can be more convenient
    • Conversion ADUs can require less work from the ground up, so the project timeline can be shorter than other ADU types if your garage is in optimal condition. Many cities also charge lower fees, and process permits much faster for conversion ADUs.
  4. They add value and bring income
    • ADUs increase property resale value and boost ROI. They can also be rented out for extra income. Long term-rentals are steady and require little maintenance.

ADUs can add value to your home both practically and financially, but before you get started, take a quick look at the steps involved in converting a garage.What are the steps to building an ADU Garage Conversion in Los Angeles?Like all construction projects, there are some moving parts to garage conversion, so here’s a quick breakdown of the process:

  1. Understand the project goals – what do you want out of your garage conversion? Establishing a desired end use for the garage – whether it’s space for a family to live, a place to rent, or something else – is important early on.
  2. Examine the specifics of the property, including zoning and lot size, to determine if your garage is eligible for conversion. An ADU specialist like Cottage will provide the best insights here.
  3. Assess your budget and costs involved with converting your garage.
  4. Draw up plans and submit them for approval to the local municipality. Cottage is a go-to resource here.
  5. After your plans are approved, a licensed general contractor will need to build it. Cottage works with a trusted network of contractor partners to build all of our ADUs.

Importantly, Cottage was founded to help homeowners conveniently navigate all of these steps. We can help you through all steps of the ADU journey – from feasibility, to design, permitting, and construction – so you can avoid common errors and get to your new ADU faster than going it alone.Also, this process is the same across LA, but before you go ahead with your garage ADU project, there are a few things to consider when assessing your eligibility for conversion, so let’s explore that next.How do you know if your garage is eligible for conversion?You are allowed to build an ADU on a legal single-family or multi-family property. Multi-family properties include duplexes, row houses, and townhouses. Note that ADUs aren’t allowed to be built if the property is located in a Very High Fire Hazard Severity Zone (VHFHSZ).Your garage should be permitted, not pose any health or safety risks, and be compliant with Building and Fire Codes. It’s generally best to have your garage assessed for usability to make sure it is structurally sound and can withstand conversion. It’s also a good idea to check for water damage and determine whether you’d need to fix up your roofing, foundation, and framing before converting.Once you’ve confirmed that your garage is eligible for conversion, you can start preparing to build your ADU.Your ADU may need to abide by certain regulations based on where you’re hoping to build, so keep reading for a comprehensive look at the rules for building in different parts of LA.What are the requirements for a garage conversion ADU in LA?Garage conversions are quite popular because they are sometimes easier to carry out than other ADU projects — conversion ADUs can have fewer requirements than new attached and detached ADUs, but this can vary depending on whether you’re building. The following regulations apply to all areas in Los Angeles:

  1. ADU size: In single-family and multi-family residences, attached garage conversion ADUs are not limited to maximum square footage, but detached garage conversion ADUs should be less than 1,200 sq. ft.
  2. Zoning: If your property is zoned for single-family or multi-family use, then you may be eligible to build an ADU on your lot. Only residentially zoned lots are eligible to build ADUs.
  3. Lot size: As long as an ADU fits on your lot, you can build one. Given that garage conversions make use of existing space and don’t add any square footage onto your property, they are always allowed.
  4. ADU height: Garage ADUs must be the same height as the original garage and don’t have additional height restrictions, but any new areas added to a single-family lot must be under 25 ft. New areas added to a multi-family lot must be between 16-18 ft.
  5. Number of units: You are allowed to add one ADU (either conversion, detached, or attached) and one Junior ADU (JADU) onto your lot, regardless of how much available space you have.
  6. Minimum size: Your garage ADU may be a minimum of 150 sq. ft. and no larger than half the size of your primary dwelling. Attached garage ADUs must also be the same size as the original garage, with the exception of a 150 sq. ft. expansion to accommodate ingress and egress.
  7. Access: Whether attached or detached, garage ADUs must have their own entrance. Attached garage ADUs may also have an internal entrance that connects to the primary residence.
  8. Setbacks: Conversion ADUs may abide by the same setback requirements of the original structure. Since conversion projects make use of the existing floor area, they don’t have any additional setback requirements.
    • Your garage ADU may sit on the property line, but you may not install windows on walls that are set back less than 4 ft. If you are expanding beyond the existing footprint, you’d need to maintain 4 ft. side and rear setbacks.
  9. Parking: If you are converting a garage, you must have at least one usable parking space for your property. This parking space may be located anywhere within setbacks and must measure at least 8.5 ft. x 18 ft.
    • When converting a garage to an ADU, you do not need to replace the lost parking space. You are also not required to create a parking space if your unit is within half a mile of public transport, one block from a car share, or located within a historic district.
  10. Energy: Conversion ADUs aren’t required to install solar power systems in accordance with the California Energy Code.
  11. Owner-occupancy: Owner occupancy is not a requirement for permitting an ADU from January 1, 2020 until January 1, 2025. If you’re converting your detached garage into a JADU, you’d need to occupy your primary residence if you’re planning to rent it out.

Some of the general requirements above vary among the City of LA, and the incorporated and unincorporated areas in the county.Additional requirements for The City of Los AngelesSome cities fall under the City of LA, so you can use the ZIMAS tool to find out the relevant details for your property, such as its exact jurisdiction. Apart from the general regulations, there are some fire-safety, interior environment, and utility requirements that are specific to the City of LA:

  1. Fire-safety: You are required to install a sprinkler system in your ADU if your property is located more than 1.5 miles from Los Angeles City Fire Department services.
  2. Interior environment: Each habitable room in the unit must be at least 70 square feet in area and 7 feet in height. These rooms must also have natural ventilation and lighting unless a mechanical ventilation system and artificial lighting are provided. The unit as a whole must have heating facilities capable of maintaining a room temperature of at least 68°F.

In addition, your garage conversion must have its own permanent provisions for cooking that are separate from the main residence, including a sink, cooktop, and refrigerator. It must also have its own separate bathroom with a toilet, sink, and bathtub or shower.

  1. ADU utilities: Aside from solar panels, receiving antennas, and exhaust vents, you may not install HVAC equipment on the roof of your house or garage. Equipment that is installed on the roof must be covered from view from any PROW in Hollywoodland.

When converting a garage, you may not be required to install a new or separate utility connection or pay a connection fee.The City of LA may not permit a garage conversion if your garage is under power lines. You may apply to relocate these power lines, but it may be costly and time-consuming.Overall, converting a garage to an ADU is a less time-consuming and expensive process, thanks in part to the fact that permitting conversion ADUs is a much quicker process than for new projects.Keep reading to know the requirements for garage ADUs in the incorporated areas of LA.Additional requirements for other 87 incorporated cities - Long Beach, Santa Clarita, Glendale, Pasadena, and moreWhile most incorporated cities follow the same structural regulations for size, height, setbacks, and more, some have their own unique requirements.

  • For example, in Santa Clarita, homeowners would need clearance from the City’s Urban Forestry Division if their property contains oak trees, so if you were planning on renovating your garage, you must get approval before any development can occur.
  • In Pasadena, garage conversions for historic properties must retain the original structure of their windows and doors. That said, exceptions are made if keeping existing windows and doors would prevent the creation of the ADU.

It’s best to look into area-specific laws and make sure you’re staying up to code. Read on for the regulatory differences applicable to the unincorporated areas of Los Angeles.Additional requirements for unincorporated communities - Altadena, Rowland Heights, Del Aire, and moreAside from the regulations we’ve mentioned above, some of the unincorporated cities in LA have specific requirements as well. For one, Altadena follows the state’s 4 ft. rule for setbacks but additionally requires that the ADU remain 6 ft. away from the existing main dwelling. However, exceptions are made if they are existing accessory structures and single-family homes that are converted into ADUs. In addition, the sizes of these units can be anywhere from 150 to 1,200 square feet.Here are a few other requirements that are common to many of LA’s unincorporated cities:

  1. Fire-safety: Your conversion ADU can abide by the same fire-safety requirements as your primary residence. This means that you wouldn’t need to install a sprinkler system if it wasn’t required of your main home.

If you’re converting a detached garage, you may need to install fire-rated exterior walls, depending on the distance between it and your primary residence.

  1. ADU utilities: Water heaters, solar, air conditioning compressors, and underground utilities may not be installed within 5 ft. from the property line without approval from the LA County Planning Department.

Your garage ADU needs its own insulation and an HVAC system that is separate from the primary residence.As it is its own structure, your garage ADU needs its own electrical permit. Load calculations must be performed to determine whether or not the existing electrical service is enough to support your ADU.Gas lines and water service must be installed no less than 18 inches below grade (ground level), and must have shut-off valves at all connection points. Gas lines may not run underneath any structures.Sewer lines must be installed at least 12 inches below grade and 24 inches outside of your foundation. According to Plumbing Code Requirements, it is recommended that you install 2-way cleanouts in certain locations and intervals. You’d need to submit a Backwater Valve Form before installing or modifying sewer lines.Garage ADUs less than 2 ft. from the property line may need a rain gutter system with downspouts for drainage purposes. You must divert any runoff away from Public Right of Way (PROW) and neighboring properties.In addition to these regulations, ADUs also need to obtain permits from the relevant authorities.How do you permit a garage conversion ADU in Los Angeles?If you are located in an unincorporated area, you’d need to reach out to Regional Planning to ensure you are abiding by the relevant regulations. The process is mostly similar when permitting an ADU in the City of Los Angeles, except you’d be speaking with your local authorities instead. As a general rule though, these are just some of the minimum submittal requirements for permitting an ADU in Los Angeles County:

  • Site plan
  • Floor plan
  • Roof plan
  • Foundation plan
  • CF1R certificate of compliance for Building Energy Efficiency

The first step to permitting an ADU in LA is to submit a Base Application to Regional Planning and pay the application fee. This process should take approximately 60 days.Demolition work needs prior approval from the Los Angeles County Environmental Programs Division (EPD) and Southern California Air Quality Management Division (SCAQMD).Permitting fees count as soft costs, and are just a fraction of your total project expenses. Here’s a quick breakdown of how much it might cost you to convert a garage.How much does a garage conversion ADU in Los Angeles cost?The cost of converting a garage into an ADU may vary depending on the location of the property, the complexity of the project, and the state of the original garage. If the garage is older, a conversion may cost more due to the additional work needed to bring it up to code.While some locations in Los Angeles require building permits for garage conversions, others don’t. These permits typically cost around $8000 for a 1,200 sq. ft. unit, but could also range from $1,000 to $20,000, depending on your location, the size of your property, and your design costs.All things considered, your garage conversion ADU project may cost a few hundred thousand dollars, but this is a worthwhile investment. If your garage isn’t seeing much use and you’d like to maximize your living area, a garage conversion is a great solution and can help boost your property value!How can Cottage help with your garage conversion?We’ve got several floor plans for you to choose from, but there are a few in particular that are popular among our customers for garage conversions:

  1. Greentree
  • 0 bedroom, 1 bathroom
  • Floor area: 240 sq. ft.
  1. Madison
  • 1 bedroom, 1 bathroom
  • Floor area: 364 sq. ft.
  1. Nelson
  • 1 bedroom, 1 bathroom
  • Floor area: 450 sq. ft.

Our team at Cottage specializes in ADUs and is backed by a network of trusted contractors and experts. We are committed to delivering a customized, budget-optimized ADU that fits your vision and property needs.

Interested in pursuing a garage conversion? Reach out to us to explore your options.


How much do ADU permits cost in Los Angeles?

The cost of permitting depends on your exact location and the scope of your project, but you can expect to pay around 10% of your total project expense in soft costs. This would work out to a few thousand dollars.

Does converting a garage to an ADU add value?

Yes! Detached and attached ADUs can add value to your property, but garage ADUs are a great space-saving way to make the most of your home and earn additional income as well.

How long does garage conversion take?

A garage conversion can be faster or slower than building from the ground up, depending on the scope of your project and the amount of overhaul needed to bring your garage up to code.

What should you consider before converting a garage?

The most important thing to consider is the stability of your existing garage — if there are structural issues, you may need to demolish and rebuild or reinforce certain elements before converting.

Is converting a garage better than adding a new ADU?

Garage conversion comes with its benefits — if your garage is in good condition, it can be cheaper, faster, and easier than building a new detached or attached ADU. But new ADU projects may increase your property value by more and can bring in more rental income.