What are the requirements to build ADU in Marin?
Constructing an ADU in Marin allows you to expand your living space and enhance property value and potential resale value. To ensure a successful project, it's crucial to comprehend Marin's local regulations and carefully assess the financial aspects of construction. This guide offers detailed insights into Marin's ADU regulations and important financial considerations, helping you plan and execute your project efficiently.
Number of ADUs on a property
How many ADUs can you build in Marin?
In Marin, you can build up to 1 ADU, provided that one unit is accommodated within an existing or proposed single-family residence or outbuilding, while the other is housed in a newly constructed outbuilding.
How many ADUs does Marin allow for multifamily properties?
In Marin, within a multi-family building, you can build 1 ADU, limited to 25% of the legal units for buildings with 5 or more units, along with the allowance for up to 2 detached ADUs.
Setbacks for an ADU
What are the setbacks required for an ADU in Marin?
ADUs should follow the setback regulations in Marin, including a front yard setback of at least 25 feet, and rear and side setbacks of four feet. However, specific guidelines for corner or through lots have not been outlined by the city.
What is the minimum distance the ADU must be from existing structures?
The minimum distance an ADU should be from existing structures in Marin is 5 feet.
Are setbacks required if converting existing structures into ADU?
In Marin, setbacks are not specifically mentioned when converting existing structures into ADUs.
Find out FREE if the zoning designation for your property allows you to build an ADU
The size of ADU for properties with a single-family home
How big can an attached ADU be in Marin?
In Marin, an attached ADU within an addition to an existing single-family residence can't go beyond 50% of the existing residence's floor area. Exceptions apply: a one-bedroom unit can be up to 850 square feet, and a two or more-bedroom unit can be up to 1,000 square feet, even if it surpasses the maximum floor area ratio standard.
How big can a detached ADU be in Marin?
A detached ADU in Marin can be up to 850 square feet for a one-bedroom unit and up to 1,000 square feet for a two or more-bedroom unit. These sizes are allowed even if they surpass the maximum floor area ratio standard.
Is there a minimum size of an ADU?
Yes, in Marin, the minimum size requirement for an ADU is equivalent to that of an efficiency unit, which typically has a minimum floor area of 150 square feet.
Can you convert existing space to an ADU?
Yes, converting existing space within a single-family dwelling into an ADU is allowed in Marin.
The size of ADU for properties with a multi-family home
How big can an attached ADU for a multifamily building be in Marin?
In Marin, the size of an attached ADU for a multifamily building is regulated. Typically, it can't be larger than 50% of the existing residence's floor area. However, there are exceptions: a one-bedroom unit can reach up to 850 square feet, and a two or more-bedroom unit can be up to 1,000 square feet, even if it surpasses the maximum floor area ratio standard.
How big can a detached ADU for a multifamily building be in Marin?
In Marin, a detached ADU for a multifamily building can have a maximum size of 850 square feet for a one-bedroom unit and up to 1,000 square feet for a two or more-bedroom unit. These dimensions are allowed even if they surpass the maximum floor area ratio standard.
Can you stack detached ADUs on top of each other?
At present, in Marin, there are no specific rules regarding the stacking of detached ADUs on top of each other.
Can you attach two ADUs to each other?
No, it's not allowed to attach two ADUs together in Marin. While the area allows for up to two different ADUs on a property with an existing multifamily building, regulations prohibit their attachment.
Can you convert existing space to an ADU?
Yes, it's allowed in Marin to convert existing space within a multifamily dwelling into an ADU.
The height for ADU
What is the max height for an ADU on a property with a single family house?
The maximum height for an ADU on a property with a single-family house in Marin is 16 feet.
What is the max height for an ADU on a property with a multifamily building?
The height limit for an ADU on a property with a multifamily building in Marin is also 16 feet, just like regulations for single-family properties.
Can you build a 2-story ADU in Marin?
No, constructing a two-story ADU is not allowed in Marin due to the maximum height restriction of 16 feet.
The parking requirements for ADU
What is the parking requirement for an ADU in Marin?
Marin County does not have specific requirements for parking associated with ADUs.
Where can a parking space be located?
Marin County regulations do not specify the location for parking spaces associated with ADUs.
Design requirements for ADU
How many bedrooms can an ADU have in Marin?
ADUs in Marin should have at least 1 bedroom, setting them apart from studio units.
Does an ADU need a kitchen in Marin?
Yes, ADUs in Marin should include a kitchen for cooking purposes.
Does an ADU require independent utility meters?
Marin does not provide specific guidelines regarding the need for separate utility meters for ADUs. For further clarification, it is suggested to consult the relevant authorities.
What is the minimum ceiling height?
In Marin, the minimum ceiling height for habitable spaces, including ADUs, is typically 7 feet, as outlined by the California Building Code.
Get the size of the ADU possible to build on your property after applying all these regulations
Permits for ADU
How long does it take to get an ADU permit in Marin?
In Marin, it usually takes about 60 days to secure an ADU permit, as the plans should undergo thorough review before the permit is issued.
When do you need a licensed professional to design an ADU in Marin?
Engaging a licensed expert, like an architect or engineer, is recommended when planning an ADU in Marin, particularly for unconventional construction approaches.
Does Marin require in-person submission of plans for an ADU?
Marin requires in-person submission of plans for ADUs and does not offer electronic submission options.
Does Marin require coastal development permits?
Yes, Marin County requires coastal development permits, though there are exceptions. These exceptions cover tasks like installing, testing, or replacing utility connections between existing service facilities and approved developments.
Economics of ADU
How much does it cost to build an ADU in Marin?
Building an ADU in Marin typically costs around $380 per square foot, which includes expenses for permits, architectural design, and engineering services. For instance, constructing a 900-square-foot ADU would generally amount to about $390,000, covering both soft and hard costs.
Is it profitable to build an ADU in Marin?
To evaluate the financial viability of constructing an ADU in Marin, it's essential to compare construction costs with local real estate market values. For example, a 900-square-foot ADU could potentially be valued at around $500,000. With construction costs estimated at $390,000, this suggests a potential return on investment of approximately 26%.
Additionally, profitability considerations may include potential rental income or the advantages of housing family members on the same property.
Can you sell an ADU in Marin?
Statewide regulations like AB 1033 allow for the possibility of selling an ADU or converting it into a condominium, which may involve creating a Homeowner Association (HOA) to oversee the transactions.
Are ADUs rent controlled in Marin?
No, ADUs in Marin County are not covered by rent control regulations. Landlords can increase rents annually for ADUs following provisions like AB 1482, which mainly apply to properties 15 years or older.
How to get money to build an ADU in Marin?
To finance ADU construction in Marin County, you can use the CalHFA’s ADU Grant Program, which provides grants of up to $40,000. These funds can be used for expenses such as architectural designs, permits, and site preparation, helping to support the development of ADUs as an affordable housing solution.