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What are the requirements to build ADU in San Marcos?
In San Marcos, adding an ADU offers a great opportunity to expand your living area, support multigenerational living, or create a separate space for aging in-laws. To ensure your ADU project is successful, it's crucial to understand the local regulations that apply to your property and assess the financial viability of building an ADU in San Marcos City. This guide presents a thorough overview of San Marcos's ADU requirements and important financial factors to help you plan and execute your project efficiently.
ADU regulations for properties with a single-family home
How many ADUs can you build in San Marcos?
In San Marcos, single-family zoned properties can have up to one ADU, either attached or detached from the primary building.
How large can an attached ADU be in San Marcos?
Attached ADUs in San Marcos cannot be larger than 50 percent of the living area of the primary dwelling, with a minimum size of 800 square feet. For one-bedroom units, the limit is 850 square feet, and for those with more than one bedroom, it is 1,000 square feet.
How large can a detached ADU be in San Marcos?
For detached ADUs on lots smaller than one acre, the maximum gross floor area is 850 square feet, except for units with more than one bedroom, which can reach up to 1,000 square feet. On lots of one acre or larger, detached ADUs can have a maximum gross floor area of 1,000 square feet.
Can I build a 2-story ADU in San Marcos?
No, it is not allowed to build a 2-story ADU in San Marcos. The rules state that the ADU cannot be taller than one story, reaching up to 16 feet at the roof's peak.
Is there a minimum size for an ADU?
No, there isn't a minimum size requirement for ADUs in San Marcos.
Can I convert the existing space to an ADU?
No, the municipal code does not state a conversion of ADU within the single-family zone.
What is the maximum height for an ADU?
On a property with a single-family house in San Marcos, a detached ADU cannot be higher than one story, reaching up to 16 feet at the peak of the roof. Its overall height should match the requirements of the applicable zone where the ADU is located. If the ADU is built above a garage, the height restriction applies to the living space, not the garage itself.
ADU regulations for properties with a multi-family building
How many ADUs does San Marcos allow for multifamily properties?
For multifamily properties in San Marcos, up to two detached ADUs are allowed per lot zoned or developed for multifamily residential use.
How large can an attached ADU for a multifamily building be in San Marcos?
In San Marcos, attached ADUs for multifamily buildings cannot be larger than 50 percent of the living area of the proposed or existing primary dwelling, with a maximum square footage of at least 800 square feet. For one-bedroom units, the maximum limit is 850 square feet, and for those with more than one bedroom, it's 1,000 square feet.
How large can a detached ADU for a multifamily building be in San Marcos?
The size of a detached ADU for multifamily buildings depends on the size of the lot. For properties smaller than one acre, detached ADUs are permitted a maximum gross floor area of 850 square feet, except for units with more than one bedroom, which can have up to 1,000 square feet. On lots one acre or larger, detached ADUs can have a maximum gross floor area of 1,000 square feet.
Can I stack detached ADUs on top of each other?
San Marcos regulations do not explicitly address whether stacking detached ADUs is allowed.
Can I attach two ADUs to each other?
No, because the San Marcos municipal code does not specify this, and it would depend on the city's planning department.
Can I convert the existing space to an ADU?
Yes, it's allowed to convert parts of existing dwelling structures that are not currently used as livable space into attached ADUs on eligible properties.
What is the maximum height for an ADU on a property with a multi-family building
On a property with a multifamily building in San Marcos, the maximum height for a detached ADU is restricted to one story, with a peak roof height of up to 16 feet. The overall height should comply with the regulations of the zone where the ADU is located. If the ADU is constructed above a garage, the height limitation pertains to the living space, not the garage structure itself.
What ADU types are allowed to build in San Marcos?
Homeowners in San Marcos have various options for adding an ADU to their property:
Detached ADU: A separate structure from the main residence.
Attached ADU: A unit connected to the main house.
Converted ADU: Converting existing spaces (like garages or sheds) into livable areas, including essential features such as kitchens and bathrooms.
Converting existing structures like garages or sheds might offer more flexibility in zoning regulations, such as setbacks and height limits, making them suitable for smaller projects. However, renovation of older structures could uncover unforeseen issues, resulting in higher costs.
ADU setbacks from the property lines and other buildings
What are the required setbacks for an ADU in San Marcos?
For an ADU in San Marcos, the minimum setbacks are 4 feet for both the rear and side lot lines. However, the city has not specified setback regulations for corner or through lots.
What is the minimum distance the ADU must have from existing structures?
The ADU needs to be at least 10 feet away from any structure already on the property, measured from eave to eave.
Are setbacks required when converting existing structures into ADU?
No. If you're converting existing structures into an ADU in San Marcos, no setbacks are required.
Can I build an ADU in the front yard of my house in San Marcos?
You can place an ADU in the front yard only if no other area of the property can accommodate a unit of at least 800 square feet. It's essential to follow all zoning setback requirements.
Design requirements for ADU
How many bedrooms can an ADU have?
In San Marcos, an ADU should have at least one bedroom, as opposed to being a studio unit.
Does an ADU need to have a kitchen?
Yes, in San Marcos, an ADU needs to have a full kitchen, as opposed to an efficiency kitchen for JADUs.
Does an ADU require independent utility meters?
Maybe, because whether an ADU requires independent utility meters depends on the local agencies with jurisdiction over utilities. They will decide if a new or separate utility connection is needed between the newly constructed ADU and the utility. However, if the ADU is created within the proposed space of a single-family dwelling or existing space of a single-family dwelling or accessory structure, it typically wouldn't require a new or separate utility connection.
What is the minimum ceiling height?
The California Building Code specifies that the minimum ceiling height for an ADU in San Marcos is 7 feet.
Find out the maximum ADU size for your property here
The parking requirements for ADU
What is the parking requirement for an ADU in San Marcos?
There is a requirement for at least one on-site paved parking space in addition to the parking required for the primary dwelling unit. These additional parking spaces should have a minimum dimension of 9 feet by 18 feet.
Where can I have a parking space on my property?
Parking for an ADU can be either off-street in setback areas decided by the city or through tandem parking. But if the City finds it's not feasible due to site or safety conditions, they may need more specifics. If the ADU is built within an existing garage, carport, or covered parking area, there might not be a need to provide replacement parking spaces.
How to get permits for your ADU
How long does it take to get an ADU permit in San Marcos?
The permitting process usually takes about 3.5 to 4 months. Once the permit drawing set is finished, either you or your architect should submit it for a Plan Check. Scheduling a pre-plan check meeting with a city planner is advised to review the application beforehand.
After submission and full payment of fees, the city has 60 days to confirm whether the application is complete. If the city doesn't respond within this period, the permit is automatically granted. If corrections are requested, your designer should address them and resubmit the plans. The application should clearly show that all ADU requirements are met, and missing details alone cannot justify denial. The Plan Check fee for ADUs in San Marcos is estimated at $135.
Does San Marcos require in-person submission of plans for an ADU?
No, San Marcos doesn't require in-person submission of plans for an ADU. Instead, they ask for digital submission of plans and supporting documents in PDF format for all types of permits, including ADUs.
Does San Marcos require coastal development permits?
No, San Marcos does not require coastal development permits in any part of the city.
When do you need a licensed professional to design an ADU in San Marcos?
In San Marcos, whether you need a licensed professional to design your ADU mostly depends on how complicated the project is.
How Much Value Does a Mother-in-Law Suite Add to Your Home?
How much does it cost to build an ADU in San Marcos?
Building an ADU in San Marcos costs approximately $325 per square foot. Additional expenses such as permits, architect fees, and engineering costs should also be factored in. For example, the total expenditure for constructing a 900-square-foot ADU totals about $330,000, consisting of both soft and hard costs.
Is it profitable to build an ADU in San Marcos?
Determining the profitability of constructing an ADU in San Marcos hinges on construction expenses and the local real estate market conditions. A 900-square-foot ADU in San Marcos carries an estimated market value of roughly $540,000. Given a total project cost of approximately $330,000, this results in an approximate return on investment of 65%.
Profitability can also be assessed based on potential rental income or the advantages of accommodating family members on the same property.
Can you sell an ADU in San Marcos?
California law allows local governments to establish regulations for the sale of ADUs and primary residences as condominiums, provided they comply with existing development standards.
In San Marcos, local ordinances govern the sale of ADUs. An ADU can be sold if it was constructed by a certified nonprofit organization, if a valid tenancy-in-common agreement is in place, or if the city approves the separate sale of the ADU and the main residence as individual condominiums.
Are ADUs rent-controlled in San Marcos?
No, ADUs in San Marcos are not subject to rent control. Since they're considered new constructions, regulations like those outlined in AB 1482, which involve rent control, do not apply. This regulation only affects buildings that are at least 15 years old.
How do I get money to build an ADU in San Marcos?
In San Marcos, homeowners can get financial help from the California Housing Finance Agency (CalHFA) to build ADUs. Through the ADU Grant Program, eligible homeowners can receive grants of up to $40,000. This money, part of a state initiative to support ADU construction, doesn't have to be paid back, offering assistance without increasing homeowners' debt.