TL;DR: What Homeowners Should Know About Unpermitted ADUs
An unpermitted ADU in San Diego may be eligible for legalization, especially if it was built before January 1, 2020, but it still needs to be evaluated for safety, code concerns, structure, utilities, and habitability.
The process may involve permit records, plans, inspections, corrections, and possibly selective opening of walls or ceilings so hidden work can be reviewed. Garage conversions, detached units, and converted bonus spaces each have different concerns.
Before assuming the ADU must be removed, start with an evaluation. We can help review the structure, identify likely concerns, and discuss what may be needed before you apply for an ADU permit or retroactive permit.
Finding out that an ADU may not be permitted can feel overwhelming.
Maybe you bought the property with a converted garage, detached unit, or backyard living space already in place. Maybe a prior owner built it years ago. Maybe your family has been using the space for guests, relatives, or rental income, and now you are wondering whether it was ever legally approved.
The first thing we want you to know is this: you are not the only homeowner facing this question.
San Diego has many properties with older garage conversions, detached living areas, bonus rooms, and informal rental spaces. Some were built before ADU rules became more common. Some were built with partial permits. Some were never reviewed at all.
The good news is that California and the City of San Diego do have pathways that may help certain homeowners legalize unpermitted ADUs or JADUs. The City of San Diego’s Information Bulletin 242: How to Obtain a Permit to Legalize Unpermitted Accessory Dwelling Units and Junior Accessory Dwelling Units explains that its streamlined legalization program applies to certain ADUs and JADUs constructed without a building permit before January 1, 2020.
The City’s 2026 Regulatory Updates also notes that AB 2533 limits a city’s ability to deny a permit for an unpermitted ADU or JADU constructed before January 1, 2020 solely because it violates building standards or ADU/JADU regulations, unless correction is necessary because the structure would otherwise be substandard.
California HCD’s Accessory Dwelling Unit Handbook, updated March 2026, similarly explains that local agencies generally may not deny permits for qualifying unpermitted ADUs or JADUs built before January 1, 2020 solely because they violate building standards, State ADU Law, or local ADU/JADU rules, while health and safety issues remain central to review.
That does not mean every unpermitted ADU is automatically approved. It means there may be a path forward once the structure is evaluated properly.
This article is not legal advice. It is homeowner guidance from our perspective as a San Diego general contractor helping families understand construction, permitting, and correction considerations before making decisions.
Jump to find the answers to your questions:
Can we legalize an unpermitted ADU in San Diego?
In many cases, yes, an unpermitted ADU may be eligible for legalization in San Diego. The correct answer depends on when it was built, how it was built, where it sits on the property, and whether it can meet required health and safety standards.
We know homeowners often hear the phrase “unpermitted ADU” and immediately assume the worst. They imagine demolition, fines, or losing a space they rely on. Sometimes serious corrections are required, but many situations begin with evaluation rather than removal.
An ADU is not just an extra room. It is a dwelling unit. That means it must be safe for someone to live in. The review may include structure, electrical systems, plumbing, fire safety, ventilation, insulation, ceiling height, windows, exits, and sanitation. If the space includes a kitchen, bathroom, sleeping area, and separate living function, it may be treated very differently than a storage room or guest room.
The City of San Diego’s ADU guidance explains requirements for obtaining building permits for ADUs and JADUs, and notes that general regulations are found in the San Diego Municipal Code. It also notes that some rules differ in the Coastal Overlay Zone, which matters for many San Diego properties.
When we evaluate an unpermitted ADU, we are looking for practical construction concerns first. Is the structure sound? Is there safe electrical service? Was plumbing installed properly? Is there adequate ventilation? Does the space appear to have been built as habitable living area? Are there obvious fire or safety concerns?
From there, the next step may involve drawings, engineering, permit applications, or coordination with the City. If the ADU was built before certain state-law cutoff dates, there may be additional protections or pathways available, but those do not eliminate the need to address health and safety issues.
Our role is to help you understand the construction side of the problem before you make assumptions. If the ADU can be legalized, the work usually begins by understanding what exists now and what may need to be corrected.
What if the ADU was built before January 1, 2020?
If the ADU or JADU was built before January 1, 2020, the build date may matter because California has updated rules for legalizing certain unpermitted accessory dwelling units.
The California Department of Housing and Community Development’s Accessory Dwelling Unit Handbook, updated March 2026, explains that a local agency generally may not deny a permit for an unpermitted ADU or JADU constructed before January 1, 2020 solely because it violates building standards, State ADU Law, or a local ADU ordinance. However, the agency may still require corrections or deny the permit if needed to address health and safety concerns or substandard building conditions.
This guidance is based on California’s AB 2533 bill text, which added protections for homeowners seeking permits for certain previously unpermitted ADUs and JADUs constructed before January 1, 2020.
For San Diego homeowners, the City of San Diego’s Information Bulletin 242: How to Obtain a Permit to Legalize Unpermitted Accessory Dwelling Units and Junior Accessory Dwelling Units, explains that its streamlined legalization program applies only to qualifying ADUs and JADUs within the City of San Diego that were constructed without a building permit before January 1, 2020. The City’s 2026 Regulatory Updates page also summarizes AB 2533 and notes that these permit protections still allow the City to require corrections when needed to address substandard conditions.
For homeowners, this does not mean, “Everything is fine.” It means, “Do not assume denial is automatic.”
You may still need to show when the ADU was built. That can involve old listing photos, appraisal records, utility history, lease records, family photos, contractor invoices, satellite imagery, or other documentation that helps establish the timeline. You may also need plans showing the existing layout and construction.
The ADU will still need to be reviewed for safety. If electrical work is unsafe, plumbing is improperly installed, ventilation is missing, or the structure has serious defects, corrections may be required. The point of the law is not to approve unsafe housing. It is to help homeowners bring older unpermitted units into a safer and more formal status when possible.
This is where preparation matters. Before you begin the formal process, it helps to know whether the ADU appears structurally sound, whether utilities are properly connected, whether ceiling heights and exits are reasonable, and whether there are obvious safety concerns.
If you are not sure when the ADU was built, start gathering records now. The date may become an important part of the conversation.
Can the city make us remove an unpermitted ADU?
Sometimes removal can be required, but it is not always the first outcome.
Whether an unpermitted ADU can remain depends on the facts. If the unit can be documented, inspected, corrected, and brought into an acceptable safety condition, legalization may be possible. If the structure creates serious health or safety concerns, violates conditions that cannot be corrected, or cannot be made habitable, removal or major reconstruction may be required.
The biggest mistake is assuming the answer before the ADU is evaluated.
For example, a converted garage may have issues with insulation, fire separation, ceiling height, foundations, windows, or safe exits. Some of those issues may be correctable. Others may be expensive enough that a larger rebuild or redesign makes more sense.
A detached backyard unit may raise different concerns. It may need review for structural framing, utility connections, drainage, setbacks, fire access, or whether it was built on a proper foundation. A converted bonus room may need review for whether it truly qualifies as a dwelling unit or whether it is better addressed as part of a remodel.
There are also cases where homeowners discover that the unit is not only unpermitted but poorly built. In those situations, the question becomes less about saving the existing work and more about protecting the property.
We try to help homeowners look at this practically. If the ADU is valuable to your family or property plan, it is worth understanding whether correction is possible. If correction costs approach the cost of rebuilding properly, it may be wiser to consider a more complete solution.
The city’s role is to protect safety and enforce applicable rules. Our role is to help you understand what the structure may need from a construction standpoint so you can respond with a plan instead of panic.
What inspections are needed to permit an existing ADU?
The inspections needed to permit an existing ADU depend on what was built, what is visible, and what the City needs to verify.
Because the ADU was already constructed, inspectors may not be able to see framing, plumbing, electrical, insulation, waterproofing, or fire-rated assemblies. That means selective opening may be required. This could involve removing portions of drywall, exposing framing connections, opening access to plumbing lines, or verifying electrical work.
Common review areas may include structural framing, foundation support, electrical service, plumbing, mechanical ventilation, smoke and carbon monoxide alarms, insulation, windows, exits, fire separation, kitchen facilities, bathroom safety, and general habitability.
If the ADU includes a kitchen, the electrical load may need review. If it includes a bathroom, plumbing and ventilation become important. If it was converted from a garage, the floor, walls, fire separation, and original garage door opening may all matter. If it is detached, the foundation and utility connections may be central concerns.
This is one reason we recommend evaluation before filing blindly. If you know likely concerns ahead of time, you can prepare better for inspection and budgeting.
A San Diego general contractor can help identify which parts of the ADU may need exposure and where correction work may be likely. An engineer may be needed if structural systems are unclear. Plans may need to be prepared to document existing conditions and proposed corrections.
Inspections should not be viewed as punishment. They are part of confirming whether the ADU is safe to occupy. If the work was done well, the process may be more straightforward. If it was not, inspection helps identify what must be corrected before the space is relied upon.
How do we start the ADU legalization process?
The best first step is to gather information before committing to a path.
Start by documenting what you have. Take photos of the ADU, note how it is used, identify whether it has a kitchen, bathroom, separate entrance, heating, cooling, and utility connections. Gather any old records, photos, leases, invoices, appraisals, inspection reports, or listing materials that may show when the ADU existed.
Next, search permit history for the property. Confirm whether there are any prior permits related to the structure, garage conversion, electrical work, plumbing, or addition. If the property is in the City of San Diego, use City records. If it is outside city limits, county records may apply.
Then schedule a professional evaluation. We can walk the property, review visible conditions, identify likely construction concerns, and help determine whether you may need plans, engineering, selective opening, or correction work before moving forward.
From there, the process may involve preparing drawings, coordinating with design professionals, submitting permit applications, responding to city comments, completing correction work, and scheduling inspections.
This is also the moment to think strategically. If the ADU needs corrections, do you want to simply legalize what exists, or do you want to improve layout, finishes, safety, and function while the work is open? Sometimes combining legalization with thoughtful remodeling prevents paying twice for demolition, repairs, and finish work.
At Home Experts Construction, we help homeowners begin this process with practical construction guidance. We are not here to promise approval before the ADU has been reviewed. We are here to help you understand what exists, what concerns may be present, and what the next responsible step may be.
Final Thoughts
An unpermitted ADU in San Diego can feel stressful, but it may not be the dead end homeowners fear. Depending on when it was built, how it was constructed, and whether health and safety concerns can be addressed, there may be a path toward legalization.
The important thing is to start carefully.
Do not assume the ADU must be removed.
Do not assume it can stay exactly as it is.
Do not rely on online advice without evaluating your property.
Start with records, documentation, and a professional assessment.
If you have an unpermitted ADU, garage conversion, detached unit, or converted living space in San Diego, contact Home Experts Construction. We can evaluate the structure, discuss likely permitting concerns, and help you understand what it may take to move forward responsibly.
