If you’re a homeowner in Mill Valley, California, considering the addition of an Accessory Dwelling Unit (ADU) to your property, it’s essential to familiarize yourself with the local regulations to ensure a smooth and compliant building process. ADUs, often referred to as granny flats or in-law units, offer a practical solution to housing shortages and can provide additional income or space for family members.
Understanding ADUs in Mill Valley
An ADU is a secondary housing unit on a single-family residential lot. These units can be detached, attached, or converted from existing spaces like garages or basements. Mill Valley also permits Junior Accessory Dwelling Units (JADUs), which are smaller units within the primary residence, typically not exceeding 500 square feet.
Key Regulations for ADUs in Mill Valley
- Size Limits:
- Detached ADUs: Can be up to 1,200 square feet.
- Attached ADUs: Cannot exceed 50% of the existing residence’s floor area, with a maximum of 1,000 square feet. However, an ADU of up to 800 square feet is always allowed, regardless of other standards.
- JADUs: Limited to 500 square feet.
- Setbacks:
- Side and Rear: A minimum setback of 4 feet is required.
- Front: Must comply with the primary structure’s setback requirements.
- Conversions: No additional setbacks are required when converting existing legal structures into an ADU.
- Height Restrictions:
- Detached ADUs: Limited to 16 feet in height.
- ADUs Above a Detached Garage: The combined height of the ADU and the garage shall not exceed 25 feet.
- Parking Requirements:
- One off-street parking space is required for each ADU, except when:
- The ADU is located within one-half mile walking distance of public transit.
- The ADU is entirely within a proposed or existing primary dwelling or other existing structure.
- The ADU is located within a historic district.
- On-street parking permits are required but not offered to the occupant of the ADU.
- There is a City-approved and dedicated parking space for a car share vehicle located within one block of the ADU.
- One off-street parking space is required for each ADU, except when:
- Owner Occupancy:
- There is no owner occupancy requirement for ADUs. However, JADUs require the property owner to reside on the property.
- Design Standards:
- ADUs must maintain the architectural style of the primary residence, ensuring consistency in design and materials.
Permitting Process for Mill Valley ADUs
Mill Valley offers a streamlined, ministerial approval process for ADUs up to 800 square feet, provided they meet specific criteria. This means that if your ADU project complies with the established standards, it can be approved without discretionary review, expediting the permitting process.
Benefits of Building an ADU in Mill Valley
- Rental Income: Generate additional income by renting out the unit.
- Housing Flexibility: Provide living space for family members or guests.
- Property Value: Increase the overall value of your property with additional living space.
Next Steps: Mill Valley ADU Laws
If you’re considering building an ADU in Mill Valley:
- Consult the Mill Valley Planning Department: They can provide detailed information and guidance specific to your property.
- Review Local Ordinances: Familiarize yourself with Mill Valley’s municipal code regarding ADUs to ensure compliance.
- Engage Professionals: Consider hiring architects or contractors experienced in ADU construction to assist with design and permitting.
By understanding and adhering to Mill Valley’s ADU regulations, you can successfully add a valuable and functional space to your property.