Accessory Dwelling Unit (ADU)
As a result of State ADU laws, which is codified in Government Code §§ 65852.2 and 65852.22, local agencies are required to comply with state regulations for ADU’s regarding size, quantity, setbacks, parking, and permit processing.
What is an Accessory Dwelling Unit (ADU)?
An Accessory Dwelling Unit or ADU means an attached or a detached residential dwelling unit that provides completely independent living facilities for one or more persons and is located on a lot with proposed or existing primary residence. It shall include permanent provisions for living, sleeping, eating, cooking, and sanitation on the same parcel as the single-family or multi-family dwelling is or will be situated. These are also commonly known as in-law units or granny units or second units.
Where can I build an ADU?
The adoption of an accessory dwelling unit ordinance allows ADU’s in areas zoned to allow residential development consistent with the goals and policies of the Foster City general plan.
What are my options for ADU's if I own a single-family home?
Option #1 | Option #2 | Option #3 | Option #4 | Option #5 |
1 JADU | 1 ADU (Conversion, Attached, or Detached) |
1 JADU AND 1 Conversion ADU AND 1 New Constructed ADU (Attached or Detached up to 800 square feet) |
1 JADU AND 1 Newly Constructed ADU (Attached or Detached) |
1 JADU AND 1 Conversion ADU |
Junior Accessory Dwelling Unit or JADU is a unit of no more than five hundred (500) square feet in size and contained entirely within a single-family residence, maintains a separate exterior entrance from the main entrance to the single-family residence, maintains an interior connection to the main living area of the single-family residence. A JADU may include separate sanitation facilities or shares sanitation facilities with the existing structure. JADU Requirements (FCMC Section 17.78.060.B):
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Attached ADU is an ADU that is constructed as a physical expansion (i.e., addition) of an existing single-family residence and shares at least one (1) wall with the single-family residence. Attached ADU Requirements (FCMC Section 17.78.060.C)
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Detached ADU is an ADU that is constructed as a separate structure from the primary dwelling unit and does not share any walls with the primary dwelling unit or an existing attached accessory structure. Detached ADU Requirements (FCMC Section 17.78.060.D)
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Conversion ADU is an ADU that is created within existing space, including a portion of a primary dwelling unit or existing non-habitable space in an existing primary or accessory structure. Conversion ADU Requirements (FCMC Section 17.78.060.E)
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What are my options for ADU's in a multi-family building?
Two types of ADU's are allowed in a multi-family structure; these are Conversion ADU's and Detached ADU's.
Conversion Multi-Family ADU Requirements (FCMC Section 17.78.070.A)
Detached Multi-Family ADU Requirements (FCMC Section 17.78.070.B)
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What are the steps to obtaining permits for an ADU?
1. Fill out Building Application and ADU Neighbor Notification Form.
2. Prepare your submittal.
3. Submit online through eTRAKiT Web Portal or in-person (in-person submittal requires four (4) sets of plans).
4. Pay Fees and obtain a Business License (if needed) through eTRAKiT Web Portal.
5. Record a Declaration of Restrictions at the County Recorder’s Office.
6. Permit is issued. Begin construction.
7. Schedule for a building inspection through eTRAKiT Web Portal.
8. Receive a Certificate of Occupancy.
Building Division offers "Express Plan Check" for ADUs and JADUs. Check this PDF for additional Information.
What are the parking requirements?
Shall not exceed 1 parking space permit unit or bedroom whichever is less.
Parking exceptions are allowed if one of the following conditions are met:
- ADU located within ½ mile of public transit,
- With approved car share with issued Foster City Business License,
- Proposed ADU is a studio only (no additional bedrooms),
- ADU is located in a architecturally and historically significant area, or
- When ADU is part of the proposed or existing primary residence or accessory structure. (FCMC Section 17.78.080).
What if my ADU application is rejected?
If the City disapproves an application for an ADU or JADU, the building division shall return in writing, a full set of comments to the applicant with a list of items that are defective or deficient and a description of how the application can be remedied by the applicant. (Section 17.78.090.B)
Are there any rebates that can help me with my ADU?
Here are some rebates that you can apply for:
- Solar Rebate Program - The Residential Solar PV (solar photovoltaic technology) Incentive Program provides a one-time, $1,000 incentive to residents who choose to install Solar PV on their homes (LINK).
Resources & Helpful Links:
- Foster City Accessory Dwelling Unit Ordinance
- HCD ADU Website
- HCD ADU Handbook
- Home Sharing Your ADU
- Apply For Your ADU Permit Online Via e-Trakit
- Foster City Permit Guide
- Foster City Building Permits
- Foster City Building Permit Forms & Handouts
- Foster City ADU Neighbor Notification Form