ADU Builders San Marcos
The San Marcos ADU Guide
San Marcos, CA, USA
You’ve found the ultimate resource for building an accessory dwelling unit in San Marcos, California. Whether you’re a homeowner looking to maximize flexibility for family or an investor planning to add units, our comprehensive guide is here to assist you every step of the way. Read on for more on what you can build in San Marcos, rent rates, and to see completed & active projects we are building. You can also access detailed ADU cost & floor plan information, plus check out homeowner stories.

San Marcos ADU QUICK FACTS
What you can build
Maximum size: 1,000 square feet
Side/rear setbacks: 4 feet
Two story: Yes, above garage
Permitting timeline
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Standard Timeline: 5-7 months
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Coastal: N/A
Our ADU experience in San Marcos
SnapADU is proud to have been selected by the City of San Marcos to design their pre-approved ADU plans through a competitive bid process with over two dozen applicants. This recognition highlights our expertise in delivering high-quality, efficient, and fully compliant ADU designs as well as our experience in the city. Read more about pre-approved ADU plans.
One unusual requirement in San Marcos is that ADUs generally cannot be in the front yard (though SB-897 passed Aug 2022 will limit city’s ability to enforce this). They also require a soils report for ADUs >500 sqft. San Marcos allows for digital submissions. Turnaround times at the city are moderate.
Additionally, we have seen San Marcos projects require interaction with the Community Facilities Districts (CFD), which are commonly referred to as Mello-Roos Districts, to finance local public facilities and services. This can add months to the processing time.
What is the CFD process in San Marcos for ADUs?
A CFD is a “community facility district” that residents of the city previously voted on to create the ability for the City to collect “developer impact fees” to cover the cost associated with providing services to the residents. These fees go towards building roads, fire stations, and other public services. Every new development project in San Marcos is subject to the CFD Charge, including ADUs. California state ADU laws do not prohibit the City from assessing CFD charges.
Owners can satisfy the CFD requirement in one of two ways:
1) Vote to annex into the district, which creates a annual assessment with your property taxes (usually $1K-$2K); or
2) Pay a one -time In-Lieu Fee (typically $100K-$200K)
Only the property owners of a property/development vote on this annexation – no neighbors or 3rd parties. The City Council certifies CFD votes 4 times per year. This means that typically 3-4 months will be added to the permitting process.
San Marcos ADU Regulations & Permitting Requirements
Want to learn more about what kind of ADU you can build in San Marcos? Check out our in-depth resource guide San Marcos Regulations & Permitting Requirements outlining the ADU building code requirements. We also include what we have learned about how the city will interpret code based on actually designing & building in the city. You can also set up a consult if you want our advice on what you can build.How much will an ADU rent for in San Marcos?
Below are median rental prices by zip code and bedroom count. Be sure to run comps for your specific area or check with a realtor.
RENT RATES IN SAN MARCOS
Zip | City | Neighborhood | 1BR | 2BR | 3BR |
92069 | San Marcos | San Marcos | 2175 | 2750 | 3575 |
92078 | San Marcos | San Marcos | 2425 | 3425 | 3725 |
Source: Rentometer March 2024
Zip Codes: 92069, 92078
Neighborhoods: Richmar, College Area, University Commons, Twin Oaks Valley, San Elijo Hills, Village O
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San Marcos ADU Builders

Full Accountability. ADU Expertise. Proven Results.
As experienced ADU builders, we will anticipate the pitfalls that less seasoned or less integrated teams will miss. And the volume of ADU jobs we handle means we have gained an incredible amount of expertise that we are excited to bring to your project.
We’re 100% focused on being the best ADU builders in San Marcos.
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Generate rental income
Many homeowners add ADUs to create a new stream of rental income.
Learn More -
Bring aging parents closer
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House younger family members
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ADU Builders San Marcos
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ADU Builders San Marcos
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ADU Builders San Marcos
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We were looking at ways to invest our money. My wife and I thought, why don't we build an ADU for rental income? Also, someday we can move into it. So it has multiple purposes.
Paul & Myra Winter
Homeowners, Oceanside -
When we bought our house, Kristen was pregnant and we wanted Grandma to be around to help with the baby. And then ultimately, we wanted to be around for Mom when she gets older.
The Heards
Homeowners, Oceanside -
We decided to build an ADU because our family's property is a big lot. That's hard to find these days, especially with the cost of housing. Plus we are closer to my mom.
Marina & Will
ADU Residents, San Marcos