The Truth About ADUs in San Diego (What the DSD Won't Tell You)

By Sean Canning

Hello, I'm Sean Canning, Principal Architect here at Ten Seventy Architecture. We've spent the last decade shaping San Diego's landscape with our modern + minimalist ADU and custom home designs. 

San Diego's Accessory Dwelling Unit regulations can be very difficult to understand. In this video, I do my best to explain the city's complicated ADU regulations to help you determine if your property qualifies for a detached or attached ADU or JADU.

I also explain all of the hidden fees the City of San Diego's Development Services Department will charge you as well as some specific tips + tricks to keep costs lower.  

If you've ever considered building a Companion Unit, Granny Flat, Guest House, Accessory Unit, ADU, Junior ADU, or even a new Dwelling Unit, this video will answer some of your questions.  

If you are interested in developing an additional unit on your property and looking for help, book a free ADU consultation with us. We'll help you map out a strategy for your project, answer any questions you have, and set you on a path for success.

And if you are looking for the fastest + most cost-effective way to build a high-end ADU in San Diego, definitely check our our new pre-designed ADU offering.

The Importance of Accessory Dwelling Units in San Diego

San Diego's housing crisis isn't a secret. Each year, we're falling behind by 12,000 homes, and the ripple effects are evident. 

To tackle this, California updated its ADU regulations in 2020, but it took San Diego nearly a year to follow suit. 

As I navigated these new regulations, I discovered a realm of possibilities, and challenges, that I am eager to share.

Can Your Property Accommodate an ADU or JADU?

Whether or not you can build an ADU or a Junior ADU (JADU) on your property is a question of zoning. Commercial zones, multi-unit residential zones, and single-unit residential zones - each comes with its own rulebook. Interestingly, a commercial lot can hold an ADU, but there's a catch – you need a pre-existing residential unit.

Dwelling Units, ADUs, and JADUs: What's the Difference?

In San Diego, if you own property in a single-unit residential zone (RS), you can build a dwelling unit, an ADU, a JADU, and guest quarters. 

If you own property in a multi-unit residential zone (RM), you can have multiple dwelling units, an ADU, and guest quarters, but no JADU. Commercial zones play by their own rules. They can have ADUs, but they demand a pre-existing mixed-use development or a residential unit.

Can I Rent Out My ADU or JADU?

Many clients ask me if they can rent out their ADUs or JADUs. The answer is, yes, but it's not a free-for-all. They are designated for long-term rentals only (30+ days). 

This may disappoint you if you were planning to list your ADU or JADU on Airbnb. 

Standard dwelling units, however, can be both short- and long-term rentals. And no, guest quarters cannot be legally rented.

Size Matters: Your ADU or JADU Dimensions

While the main dwelling unit's size depends on your Floor Area Ratio (FAR), a measure of the total square footage you can build on your lot, ADUs dance to a different tune. 

With an ADU, you're looking at anything from a cozy 150 square feet to a generous 1,200 square feet. JADUs, on the other hand, range from 150 to 500 square feet.

The Dance of Setbacks

Building regulations impose 'setbacks', which refer to the minimum distance your construction needs to be from the property line. For dwelling units, these include a front yard, a street side yard (applicable only if you're on a corner lot), an interior side yard, and a rear yard setback. 

The size of these setbacks is determined by the specific zone of your property.

Here's where it gets interesting: ADUs and JADUs do not require interior side yard or rear yard setbacks. 

This means we can theoretically construct an ADU or JADU right up against the side or rear of your property. However, in practice, it's wise to leave some room for construction work and drainage installation. This is a significant benefit for ADUs and JADUs.

Height and Angled Plane Restrictions

Height limits for dwelling units are determined by the base zone. For instance, in an RS-1-7 zone, the height limit could be 30 feet. 

However, there's also something called an 'angled plane' restriction, which dictates that the structure can only rise to 24 feet at the side yard setback, after which it must remain within an angled plane, encouraging pitched-roof designs.

ADUs and JADUs, however, do not have to comply with the angled plane regulation. Consequently, they can, in certain circumstances, be taller and closer to the side yard setback than the dwelling unit. This is a huge advantage.

The Sequence of Construction and Attachment Rules

To construct an ADU, JADU, or guest quarters, there must be a dwelling unit on your property. These can be constructed simultaneously, but the dwelling unit must be constructed first. 

The ADU can be attached or detached, but the JADU has to be attached - to either the dwelling unit or the ADU. Guest quarters, on the other hand, can be attached or detached.

The JADU is unique in that it can share a bathroom with the unit it's attached to, although this arrangement might not suit all situations due to possible tenant overlap. Also, please note that owner occupancy is required for JADUs.

Understanding the Fees

The permit process requires the payment of various fees for all units: plan check and inspection fees, school fees, sewer and water fees, and impact fees.

Plan check and inspection fees are consistent across all unit types. School fees, charged by the San Diego Unified School District, are based on square footage and can be avoided in certain situations, such as additions to your dwelling unit or constructing an ADU or JADU of 500 square feet or less.

Sewer and water fees are usually $7,200 per unit. However, ADUs and JADUs are currently charged only 50% of these fees, leading to a cost saving of $3,600 compared to dwelling units.

Impact fees vary from community to community and cover costs already paid for by your property taxes. Dwelling units are subject to these fees, while ADUs and JADUs are currently exempt. If we add up the savings on sewer and water fees and impact fees, ADUs and JADUs will incur around $17,000 less in fees compared to dwelling units.

The Potential of ADUs in RS and RM Zones

In an RS zone, a vacant lot could hold one dwelling unit, one JADU, one guest quarter, and one ADU, offering three rentable units. In RM zones, there is more opportunity, with multiple dwelling units, one guest quarter, and at least two ADUs possible.

Specifically in RM zones and if located within a transit priority area, you could add two more ADUs once the first dwelling unit and two ADUs are built. One of these ADUs would be a deed-restricted affordable unit, rented at an affordable housing rate for 15 years. Upon doing so, you would earn a bonus ADU that does not have to be deed-restricted. This process can continue until you've filled the lot or maxed out the floor area ratio (FAR). So, in some cases, you may be able to fit up to eight units on a 3,500 square foot RM zoned lot.

Parking Privileges and Conditions

Parking regulations often come up in conversations around Accessory Dwelling Units. As of the current rules, ADUs and JADUs no longer require dedicated parking spaces. Additionally, there are also provisions that modify parking conditions on the property when an ADU is built.

One intriguing adjustment is that the addition of an ADU permits parking in the front yard setback, which is typically the first 15 or 20 feet of the front yard area. While this isn't typically enforced, if you're applying for a permit and you depict parking in your front yard, the addition of an ADU grants you the right to park there. Without the ADU, parking in this area could actually result in a ticket.

Moreover, some lots in San Diego are disallowed from having tandem parking, but once an ADU is constructed, tandem parking is permitted, essentially expanding parking options for the property.

Exceeding the Floor Area Ratio (FAR)

An ADU can extend past the maximum FAR by up to 800 square feet. This means even if a property has reached its floor area limit and cannot construct additional square footage outside of the existing building envelope, an ADU can still be built. Practically, this signifies that in most cases, we can fit an ADU of up to about 800 square feet on RS or RM-zoned lots.

Size of the ADU Compared to the Dwelling Unit

Contrary to common misconceptions, an ADU can be larger than a dwelling unit. There might be scenarios where the dwelling unit is much smaller, and the ADU is significantly larger, possibly up to 1200 square feet.

Owner Occupancy Requirement for JADUs

While JADUs do mandate the owner to reside on the property, this may not necessarily alleviate the housing crisis. This requirement may have been incorporated to limit the illegal renting of JADUs.

Solar Panels Requirement

As per the 2019 building code, solar panels are mandated for new ADUs or any new dwelling units.

Estimated Costs and the Permit Process

The cost for an architect to design an ADU ranges from $10,000 to $20,000, with structural engineering costs between $2,500 to $7,500. The cost for an energy compliance report is around $300 to $500, and permit costs for most ADUs are about $10,000. Construction costs generally start from $225 per square foot. It's important to note that these costs are estimates and can vary based on various factors.

Despite the shift to a digital process that was intended to simplify things, the permit process in San Diego has only become more complicated and still takes about four months or more. The quality of service varies greatly within the development services department, and your experience can depend heavily on the employee you are paired with.

Unfortunately, San Diego is not fully in alignment with the state-mandated ADU regulations that require a review to be completed within 60 days for ADUs and JDUs.

Project Timelines

It typically takes around one to two months to design an ADU project, followed by about one month for engineering and energy compliance reports. 

The permitting process is often more than four months, and the construction phase can last from six to twelve months, depending on several factors, such as the efficiency of the general contractor and the availability of materials.

Loopholes and Cost-Saving Tips

Some cost-saving tips have been uncovered in the process of designing and permitting ADUs. For instance, conversions of inhabitable spaces like garages, mechanical rooms, storage rooms into ADUs are exempt from sewer, water fees, and school fees. 

This exemption can save around $5,000 in permit fees.

Moreover, such projects are not required to install solar panels, which can often cost upwards of $10,000. If an existing dwelling unit on a property does not have fire sprinklers, any ADU built will not be subject to installing them either, offering another opportunity for cost savings. 

However, if one dwelling unit on the property has fire sprinklers, then all ADUs or JADUs will also be required to have them.

Dealing with Water Meters

The water meter is an essential aspect of any property, and most existing water meters are three quarters of an inch. With this size, you can accommodate three to four total units before you need to upgrade your water meter. If you must upgrade your water meter, the cost can go up to around $10,000 because it involves securing a right of way permit, processing fees, and hiring a contractor with a Class A license.

To avoid this expense, one trick is to stay under 40 fixture units, which allows you to keep the three quarter inch water meter. To achieve this, eliminate unnecessary water fixtures, such as hose bibs, dishwashers, washer and dryers, and bathtubs, as they significantly contribute to the fixture unit count.

Valuation and Capital Improvement Exemptions for ADUs and JADUs

ADUs and JADUs are exempt from capital improvements based on valuation, meaning that the cost of these units should not increase the project's total value. This is important because the city often uses the cost of ADUs and JADUs to increase their valuation of your project, which could trigger upgrades you weren't planning for, like a sidewalk or driveway curb cut upgrade. Ensure you review city invoices diligently to avoid these unnecessary charges.

Occupancy Classifications and Fire Sprinkler Upgrades

The type of occupancy classification you fall under can also influence your project. A duplex or one unit falls under the R3 occupancy classification, whereas a triplex or more falls under the R2 classification. The latter may require mechanical and electrical engineering plan checks, incurring additional costs. However, converting an attached garage to an ADU in a duplex, even if it turns the property into a triplex, will not trigger a fire sprinkler upgrade.

Using Pre-Designed ADUs for Cost and Time Savings

Pre-designed ADUs are an excellent option to reduce design, engineering, permitting costs, and time. They're straightforward to build, and costs can start from around $125,000. They're also designed with solar orientation in mind, enhancing energy efficiency. For instance, the model being built currently at Ten Seventy Architecture is a 525-square-foot, two-story, one-bedroom unit that can fit on lots 25 feet wide or larger.

The first-floor layout includes a bedroom, bathroom, closet, and patio, providing convenience and accessibility. The second floor houses all living spaces, a small pantry, and additional storage. High ceilings also add value to the living space, providing a sense of openness and grandeur.

In Conclusion

Designing and constructing Accessory Dwelling Units and Junior Accessory Dwelling Units can be a complex process with various factors to consider. These include parking regulations, size restrictions, the permit process, project timelines, and more. By understanding these aspects thoroughly, you can maximize the potential of your property, navigate through the process more smoothly, and avoid unnecessary costs.

Remember that while there might be loopholes and cost-saving tips, the city's requirements are there to ensure safety and compliance with the broader community's standards. Always approach the process with diligence, ensuring to review every document thoroughly and communicate effectively with your design team, contractor, and the city's Development Services Department.

Thank you for joining us in this deep dive into the world of ADUs and JADUs in San Diego. We hope this information helps you make informed decisions about your property development endeavors. Remember, the truth about Accessory Dwelling units is often more complex than what's on the surface, but with the right knowledge and guidance, the rewards can be substantial.

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