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Guide to San Diego’s Pre-Approved ADU Plans

Jul 14, 2024 | 0 comments

You may have heard that several jurisdictions in San Diego County are making pre-approved floor plans for accessory dwelling units (also known as ADUs, guest houses, second units, casitas, granny flats) available to the public. Read on to decide if permit-ready plans are the right choice for your ADU project.

What are the “pre-approved” or “permit-ready” ADU building plans?

San Diego County, Encinitas, Del Mar and Carlsbad have produced several granny flat plans to make it easier for homeowners to begin the process of adding an ADU to their property. Encinitas ADU plans are part of what is called the Permit-Ready Accessory Dwelling Unit (PRADU) Program.

Some of the San Diego County ADU plans and PRADU plans have been reviewed by building departments previously, though there is not a clear definition of “permit ready.” In our experience, many pre-approved plans are typically not the final choice for people we speak with about their ADU projects. This is due to design constraints and minimal – if any – real cost savings on the overall project.

Can I submit pre-approved plans as-is?

No; all of the pre-approved plans are only about 80% complete and will always require property-specific modification and documentation. In addition to the building plans, your project will still require Title 24 energy calculations, truss calculations, storm water plan, and a site plan (also called a plot plan).

The site plan must show the property layout with the footprints of all existing and proposed structures, electrical services, fences, walls, gates, setbacks, parcel area, easements, driveways, slopes, drainage for storm water and other features. When applicable, grading plans, septic design and other plans and calculations must be created and also submitted with the pre-approved plans in order to obtain a building permit.

Additionally, most homeowners would need to make at least some amendments to the ADU floor plan. For example, a door or window may need to be moved due to site layout or constraints. ANY change means you will still need to pay for plans to be drawn up, plus then the plan is no longer “pre-approved.” Unfortunately it’s not as simple as just “editing” the San Diego county ADU plans. A new set would need to be drawn up, meaning these changes could increase the plan cost by $2-4K.

Does using pre-approved ADU save money?

It’s probably not cheaper overall to use a pre-approved plan. Keep in mind that 90-95% of the costs of your ADU project are in construction. It’s important to note that many standard ADU plans were designed by architects and not designed primarily for building cost efficiency. Most pre-designed plans put out before 2024 were not evaluated by a builder or value-engineered (e.g. designed to require less material and to be labor-intensive). As a result, the few thousand dollars you may save on plans could quickly evaporate in significantly higher build costs.

For instance, most pre-approved San Diego ADU plans aren’t designed with trusses (much more efficient to build), “wet” walls may not be combined (which results in more expensive plumbing costs), and foundations may be over-engineered and complex (with unnecessary bearing walls and interior footings). The standard plans from jurisdictions have also not used standard sized windows and doors, or optimized around standard size shower & tub inserts. This means you’re losing cost savings, and in some cases, facing supply chain issues for more custom sizes.

However, SnapADU’s pre-approved plans designed for the City of Chula Vista and the City of San Marcos address many of these concerns. We use truss roofs, avoid costly interior footings, and allow several modifications to the plans, such as changes to door and window placements, bath and kitchen layouts, and include Title 24 calculations. These designs are intended to save time and money while still requiring site-specific adjustments.

Is using ADU pre-approved plans faster?

Maybe. Pre-approved plans are sometimes put into an expedited queue, though in most instances the pre-approval queue is just as long as the standard queue. Also, if for any reason the pre-approved plan has a deviation (e.g. because you wanted to move a window or a door), the plan will end up in the standard queue.

Our experience is that the overall approval times are comparable with any other ADU plan. Approval times are often comparable to custom plans because much of the review process involves property-specific specs, not the floor plan itself.

Also, it can save time if you select any build-ready plan, since there will be less time dedicated to creating the floorplan, elevations, and construction details from scratch. Even with custom floor plans, we recommend that clients pick a plan that is closest to what they envision and make modifications from there to expedite the design process, saving both time and money.

What is AB 1332 and why does it matter?

AB 1332 is a legislative bill in California passed in October 2023 that mandates several key requirements for local agencies regarding Accessory Dwelling Unit plans. By 2025, the bill requires local agencies to:

  • Accept ADU Plan Submissions for Pre-Approval: Local agencies must accept pre-approved ADU plans from any source, without restricting who may submit them.
  • Post All Pre-Approved Plans Online: All pre-approved plans must be made publicly available on the city’s website.
  • Accept Other ADU Plans: Agencies must accept ADU plans that have been developed and approved by other localities within the state.
  • Approve or Deny Applications Quickly: Applications for ADU permits using pre-approved plans must be approved or denied within 30 days.

This bill aims to streamline the ADU approval process, reduce bureaucratic delays, and promote the construction of more ADUs to address housing shortages.

However, we do not know many specifics yet of how cities will handle this new state requirement. As with many changes to state law, expect inconsistency in local application in the initial months. Read about how we advocate for homeowners in these scenarios.

Are SnapADU Plans Pre-Approved?

SnapADU offers pre-approved ADU plans specifically designed to meet the standards and requirements of certain California cities. These plans are crafted with cost-efficiency and building efficiency in mind, ensuring that they are both practical and compliant with local regulations.

SnapADU Chosen by City of Chula Vista and City of San Marcos

SnapADU was selected by both the City of Chula Vista and the City of San Marcos to design their pre-approved ADU plans. The selection process was a competitive bid with over two dozen applicants. This achievement highlights SnapADU’s expertise and reputation in the ADU industry, showcasing our ability to deliver high-quality, efficient, and compliant ADU designs.

Process with the Cities

The process with the cities of Chula Vista and San Marcos is currently in progress. We are working closely with these municipalities to finalize the pre-approved plans and ensure they meet all necessary criteria. Once this process is completed, we will share detailed information on how these pre-approved plans can be utilized for ADU projects. Stay tuned for more updates on this exciting development.

Has SnapADU built any of the standard ADU plans?

Yes, we have built several of the San Diego County ADU plans and PRADU standard plans – you can check out our ADU projects here. We are happy to deliver what our clients want built. In many cases though, we find that the San Diego County Standard Plans and Encinitas PRADU plans may not end up providing the best overall value for the client.

Often we’ll end up producing semi-custom plans for clients by starting with a plan that most closely represents what they are looking for, then tweaking the layout. Many clients feel any additional design cost is worth it to design something that will be exactly fit to their needs and will best utilize the available space for the ADU.

Do I need an architect if I use a pre-approved plan?

While you are not required to have to have an architect design & stamp your ADU plans, you will need to have a drafter produce the site plan, title 24 calculations, and any required structural calculations. This is assuming no changes to the floor plans themselves as discussed above. We also highly recommend that you perform a Feasibility Study to understand the full scope that will be required for your building project. It’s important to understand utilities in particular, as well as sitework costs like grading & foundation. Read more about the many costs of ADU projects you don’t want to forget to budget for.

What are different types of ADU plans?

When designing a detached accessory dwelling unit, there are a number of different ways you can go about design and construction. ADU plans can be broken up into several different categories, each with its own pros, cons, and costs.

Pre-approved ADU plans

Certain jurisdictions have put together predesigned ADUs that are about 80% of a complete set of plans, as described above. These attempt to streamline the ADU process for homeowners by offering a design off-the-shelf. While pre-approved plans are appealing in concept, these plans typically don’t offer a savings of time or money as compared with other options, plus leave homeowners stuck unable to make changes.

SnapADU build-ready ADU plans

SnapADU offers a set of build-ready plans that we have designed to be cost-efficient for homeowners, while also including all the most-requested features in ADUs. Our design team has created these plans specifically to ensure their building efficiency, using “value engineering” to shave off what we’ve found to be unnecessary costs in features that don’t affect the livability or stability of the unit (e.g. using truss systems, using standard size doors & windows, combining wet walls). Check out 1 bedroom, 2 bedroom, 3 bedroom, 4 bedroom, and two story plans.

Semi-custom ADU plans

You can modify any of the SnapADU standard plans to ensure you are happy with the design you have chosen. Modifying will potentially add on an extra cost to your ADU, depending on the type of changes you are looking to make. Modifications are categorized by difficulty and into different types, all of which you can find in our design policy. Modifications are evaluated on a case-by-case basis to ensure these changes are feasible options for your ADU.

Full custom ADU plans

This will be the most time-intensive and expensive option, as custom ADU plans are highly technical and involve designing an ADU from scratch. While this offers a lot of freedom in regard to your ADU design, it’s important to keep in mind that certain decisions can add a lot of build cost. Your designer should be able to guide you on these choices and implications. For example, a custom sized shower will likely require full custom tiling, as opposed to an off-the-shelf shower insert and finishes. This adds up quickly, which is worth noting before entertaining the idea of a custom ADU.

Why are custom ADU plans more expensive than standard plans?

There are several reasons that choosing a full custom ADU plan is more expensive vs choosing or modifying an off-the-shelf plan.

Design time & cost. Starting on a custom design will entail many more hours of a draftsman’s time to produce. If you go full custom with architecture firms, expect to pay $15K+ for plans.

Custom sizes & elements. Custom ADUs that utilize many sizes of windows and doors will have higher material and labor costs, as well as more uncertainty on lead times for materials, which can cause delays. Conversely, in semi-custom plans, we use sizes that we know are typically available to reduce costs and potential delays if we, for instance, have a window broken in transit. Standard size materials are simply cheaper to acquire, but don’t affect the livability (think about the difference in a 48” window vs a 52” window).

Management time. Highly custom designs and material selections take more manual intervention in our processes. We’ve tried to automate as much of the ADU design/build process as we can so that we can offer a high quality product at a compelling price. Once we start deviating from this norm, our team must get involved in more one-off tasks, such as sourcing material or verifying that unique setups will work. This simply takes time and therefore has a cost.

To keep costs down, consider using a standard or semi-custom plan. We understand that full-custom is the only option for some situations, for instance on a challenging lot where the space & grading constraints necessitate it. We are happy to advise on what is possible on your lot.

We’d love to take a look at your property and help advise if you are looking at San Diego ADU plans. Fill out a property assessment to get started.

Free ADU Plans in San Diego: What You Need to Know

If you’re searching for free ADU plans in San Diego, you’re in luck. Several local jurisdictions, including San Diego County, Encinitas, Carlsbad, Chula Vista, San Marcos and others, are offering pre-approved ADU plans to the public at no cost. These free plans are part of an effort to make it easier and more affordable for homeowners to add accessory dwelling units to their properties.

Benefits of Free ADU Plans

  1. Simplified Planning: Free ADU plans provide a clear starting point, simplifying the design and planning stages of your project.
  2. Streamlined Approval Process: These pre-approved plans have already been reviewed by local building departments, which can expedite the permitting process and reduce wait times in some cases.
  3. Cost Savings: You may save a few thousand dollars on floor plans if you can use pre-approved plans exactly as-is. Keep in mind you will still need to have the plans plotted on your own property-specific site plan, along with other requirements.

Customization Options

While free ADU plans offer a great starting point, they may still require customization to meet your specific needs and comply with site-specific requirements. SnapADU can help you modify these plans to better fit your property and preferences, ensuring your ADU project is both functional and compliant with all local regulations.

SnapADU’s Pre-Approved Plans

In addition to the free plans provided by local jurisdictions, SnapADU offers build-ready ADU plans designed for cost efficiency and ease of construction. Our plans are tailored to address common concerns such as construction efficiency, material availability, and regulatory compliance, ensuring a smoother build process.

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