A Junior Accessory Dwelling Unit (JADU):
Is a residential unit with a maximum of 500 square feet of interior livable space, located entirely within an existing single-family home. It must include an efficiency kitchen, which consists of appliances, a food preparation counter, and storage cabinets proportional in size to the JADU. A JADU may have its own sanitation facilities or share them with the main residence. The unit must be contained within the walls of the primary residence but does not need an interior connection to it. If the JADU lacks a separate bathroom, it must have an interior entrance to the main living area. Local agencies cannot require parking as a condition for permitting a JADU, even if the unit is created from an attached garage. A deed restriction may be applied to prevent the sale of the JADU separately from the primary residence and to regulate its size and features in accordance with state law. Additionally, local agencies may establish rental requirements, such as a minimum stay of 30 days for JADU rentals.
Is a residential unit with a maximum of 500 square feet of interior livable space, located entirely within an existing single-family home. It must include an efficiency kitchen, which consists of appliances, a food preparation counter, and storage cabinets proportional in size to the JADU. A JADU may have its own sanitation facilities or share them with the main residence. The unit must be contained within the walls of the primary residence but does not need an interior connection to it. If the JADU lacks a separate bathroom, it must have an interior entrance to the main living area. Local agencies cannot require parking as a condition for permitting a JADU, even if the unit is created from an attached garage. A deed restriction may be applied to prevent the sale of the JADU separately from the primary residence and to regulate its size and features in accordance with state law. Additionally, local agencies may establish rental requirements, such as a minimum stay of 30 days for JADU rentals.
An Accessory Dwelling Unit (ADU):
Is a self-contained residential unit located on the same lot as a primary residence. It includes independent living facilities such as a bathroom, kitchen, and laundry hookups for one or more occupants. Similar to a Junior Accessory Dwelling Unit (JADU), the kitchen within an ADU should be proportionate in size to the overall unit and typically includes a fixed appliance, such as a range. ADUs may be situated as detached structures, attached to the primary residence, or incorporated within the primary dwelling itself. This includes attached garages, storage areas, or similar spaces, as well as accessory structures. Detached ADUs, including detached garages, are permitted on the same lot as the primary residence.
ADUs up to 749 square feet are exempt from impact fees imposed by local agencies, special districts, and water districts. According to California Government Code, municipalities cannot restrict the interior livable space of an ADU to less than 850 square feet, or 1,000 square feet if the unit contains more than one bedroom. In jurisdictions without a compliant ADU ordinance, the maximum size for a new detached ADU is 1,200 square feet of interior living space, and attached ADUs may be up to 50% of the floor area of the primary residence, with a minimum of 800 square feet. Local agencies may adopt less restrictive ordinances allowing ADUs to exceed 1,200 square feet. While no deed restrictions are permitted on ADUs, similar to JADUs, state regulations allow local agencies to require a minimum rental period of 30 days for ADU rentals.
Is a self-contained residential unit located on the same lot as a primary residence. It includes independent living facilities such as a bathroom, kitchen, and laundry hookups for one or more occupants. Similar to a Junior Accessory Dwelling Unit (JADU), the kitchen within an ADU should be proportionate in size to the overall unit and typically includes a fixed appliance, such as a range. ADUs may be situated as detached structures, attached to the primary residence, or incorporated within the primary dwelling itself. This includes attached garages, storage areas, or similar spaces, as well as accessory structures. Detached ADUs, including detached garages, are permitted on the same lot as the primary residence.
ADUs up to 749 square feet are exempt from impact fees imposed by local agencies, special districts, and water districts. According to California Government Code, municipalities cannot restrict the interior livable space of an ADU to less than 850 square feet, or 1,000 square feet if the unit contains more than one bedroom. In jurisdictions without a compliant ADU ordinance, the maximum size for a new detached ADU is 1,200 square feet of interior living space, and attached ADUs may be up to 50% of the floor area of the primary residence, with a minimum of 800 square feet. Local agencies may adopt less restrictive ordinances allowing ADUs to exceed 1,200 square feet. While no deed restrictions are permitted on ADUs, similar to JADUs, state regulations allow local agencies to require a minimum rental period of 30 days for ADU rentals.
Types of ADU's:
Single-Family Detached ADU:
One detached new construction ADU that does not exceed four-foot side and rear yard setbacks is permitted on lots with an existing or proposed single-family dwelling. A Local agency may not impose a height limit less than the following:
Single-Family Converted ADU or JADU:
One ADU per lot is permitted within the converted space of a proposed or existing single-family dwelling or accessory structure. This type of ADU must have exterior access and setbacks for fire and safety but is not subject to a four-foot side and rear yard setback.
ADUs converted from accessory structures are eligible for a 150 square-foot expansion to accommodate ingress and egress. For example, if a second story from a single-family dwelling is converted into an ADU, a stairwell of not more than 150 square feet could be added, among other types of ingress and egress configurations that comply with the local building standards. In addition, one JADU per lot is permitted within the proposed or existing space of a single-family dwelling or accessory structure and must have exterior access, side and rear setbacks for fire and safety. For the purposes of constructing a JADU, attached garages are part of a single-family dwelling. A Local agency may not impose a height limit less than the following:
Single-Family Detached ADU:
One detached new construction ADU that does not exceed four-foot side and rear yard setbacks is permitted on lots with an existing or proposed single-family dwelling. A Local agency may not impose a height limit less than the following:
- 16 feet on a lot with a proposed or existing single-family or multifamily dwelling unit.
- 18 feet on a lot with an existing or proposed single-family or multifamily dwelling, including an additional 2 feet to accommodate roof pitch that aligns with the primary dwelling, when the lot is a half-mile from a major transit stop or high-quality transit corridor.
- If a detached two-story ADU can be built according to the height allowances required under State ADU Law while remaining compliant with the building code, a local agency cannot deny an ADU application to create a two-story ADU, irrespective of the underlying zoning that might restrict a primary dwelling to one story.
Single-Family Converted ADU or JADU:
One ADU per lot is permitted within the converted space of a proposed or existing single-family dwelling or accessory structure. This type of ADU must have exterior access and setbacks for fire and safety but is not subject to a four-foot side and rear yard setback.
ADUs converted from accessory structures are eligible for a 150 square-foot expansion to accommodate ingress and egress. For example, if a second story from a single-family dwelling is converted into an ADU, a stairwell of not more than 150 square feet could be added, among other types of ingress and egress configurations that comply with the local building standards. In addition, one JADU per lot is permitted within the proposed or existing space of a single-family dwelling or accessory structure and must have exterior access, side and rear setbacks for fire and safety. For the purposes of constructing a JADU, attached garages are part of a single-family dwelling. A Local agency may not impose a height limit less than the following:
- 25 feet or the height limitation that applies to the primary dwelling in the local zoning ordinance, whichever is lower. There is no limit on the number of stories contained in State ADU Law. A local agency must allow at least two stories, if this can be accommodated under the applicable height limit while complying with all applicable building standards, and an attached ADU may be built to the height of the zoning for the primary dwelling or up to 25 feet, whichever is lower.
Impact Fees:
Any Impact fees charged for the construction of an ADU or JADU must be determined in accordance with the Mitigation Fee Act and include any monetary exaction other than a tax or special assessment that is charged by a local agency in connection with the approval of an ADU or JADU for the purpose of defraying all or a portion of the cost of public facilities relating to the ADU or JADU. Local agencies, special districts, or water providers shall not categorize ADUs or JADUs as new residential uses for the purpose of calculating connection fees or capacity charges for utilities such as water and sewer services unless the unit is being constructed concurrently with a new primary single-family residence. In such cases, connection and capacity charges will be proportional to the additional burden imposed by the ADU or JADU, based on its square footage or drainage fixture units relative to the primary residence.
Any Impact fees charged for the construction of an ADU or JADU must be determined in accordance with the Mitigation Fee Act and include any monetary exaction other than a tax or special assessment that is charged by a local agency in connection with the approval of an ADU or JADU for the purpose of defraying all or a portion of the cost of public facilities relating to the ADU or JADU. Local agencies, special districts, or water providers shall not categorize ADUs or JADUs as new residential uses for the purpose of calculating connection fees or capacity charges for utilities such as water and sewer services unless the unit is being constructed concurrently with a new primary single-family residence. In such cases, connection and capacity charges will be proportional to the additional burden imposed by the ADU or JADU, based on its square footage or drainage fixture units relative to the primary residence.
Sewer Connections:
An ADU’s sewer connection must be made to the sewer lateral located between the primary structure and the street. The sewer line for an ADU cannot connect directly to the primary dwelling’s sewer line; however, a JADU may connect directly to the primary residence’s sewer system. A backflow prevention device is typically required on the ADU’s sewer lateral by the sewer utility, which may also require a backflow device for the primary residence at this time. During our feasibility assessment, we will review the sewer assessment data provided (see "Your First Steps") and evaluate the location of the ADU to determine if sufficient slope (fall) exists for proper connection to the existing sewer lateral. If the slope is inadequate, a sewage pump may be necessary. Sewer connection fees may increase based on the number of fixtures, similar to a home addition. For properties with a septic system, the existing system must be evaluated to determine whether it can accommodate the additional load from the new bedroom(s). Our feasibility analysis will include an assessment of the septic evaluation data and an estimated cost for either expanding the existing septic system or installing a new, independent septic system for the ADU.
An ADU’s sewer connection must be made to the sewer lateral located between the primary structure and the street. The sewer line for an ADU cannot connect directly to the primary dwelling’s sewer line; however, a JADU may connect directly to the primary residence’s sewer system. A backflow prevention device is typically required on the ADU’s sewer lateral by the sewer utility, which may also require a backflow device for the primary residence at this time. During our feasibility assessment, we will review the sewer assessment data provided (see "Your First Steps") and evaluate the location of the ADU to determine if sufficient slope (fall) exists for proper connection to the existing sewer lateral. If the slope is inadequate, a sewage pump may be necessary. Sewer connection fees may increase based on the number of fixtures, similar to a home addition. For properties with a septic system, the existing system must be evaluated to determine whether it can accommodate the additional load from the new bedroom(s). Our feasibility analysis will include an assessment of the septic evaluation data and an estimated cost for either expanding the existing septic system or installing a new, independent septic system for the ADU.
Water Supply:
The water supply for an ADU must connect to the service line between the water meter and the pressure regulator (if required for the primary dwelling). If a pressure regulator is necessary for the primary residence, the ADU should have its own independent pressure regulator before the service line enters the unit. A JADU may connect directly to the primary dwelling’s water supply. The increased fixture count associated with an ADU or JADU might necessitate a water meter upgrade or a service line upgrade from the meter to the primary residence, especially if the total fixture units exceed the capacity of the existing meter or supply line. This will be evaluated during our feasibility survey. If a meter upgrade is required, the homeowner should confirm with the water agency whether the water lateral—including the portion from the street to the meter—may also need replacement. Such replacements can cost upwards of $20,000. For rental properties, a private metering device can be installed on the ADU or JADU to monitor usage.
The water supply for an ADU must connect to the service line between the water meter and the pressure regulator (if required for the primary dwelling). If a pressure regulator is necessary for the primary residence, the ADU should have its own independent pressure regulator before the service line enters the unit. A JADU may connect directly to the primary dwelling’s water supply. The increased fixture count associated with an ADU or JADU might necessitate a water meter upgrade or a service line upgrade from the meter to the primary residence, especially if the total fixture units exceed the capacity of the existing meter or supply line. This will be evaluated during our feasibility survey. If a meter upgrade is required, the homeowner should confirm with the water agency whether the water lateral—including the portion from the street to the meter—may also need replacement. Such replacements can cost upwards of $20,000. For rental properties, a private metering device can be installed on the ADU or JADU to monitor usage.
Electrical Service:
PG&E requires a separate meter for each dwelling unit, which is typically triggered by the assignment of a new address (necessary for both ADUs and JADUs). In the case of a JADU, which is not considered a separate dwelling unit, a new address may still lead to the requirement for a separate meter. The Energy Code mandates that provisions and capacity for an electric vehicle (EV) charger be included in newly constructed ADUs when parking spaces are provided. Additionally, the Energy Code specifies that any newly constructed ADU must be equipped with a Battery Energy Storage System or be prepared for future installation.
The installation of a new electrical meter is a lengthy process and should commence promptly upon permit issuance or sooner. Please coordinate with your electrician regarding the appropriate timing for your project. While some projects may not immediately attract PG&E attention, future inspections or visits could result in new meter requirements.
Please be aware of potential metering surprises, such as the spacing requirements for existing gas and electrical meters on the primary dwelling. PG&E requires a minimum clearance of 36 inches from the vent on the gas meter to the edge of the electrical panel. Certain situations may necessitate panel or vent relocation. We recommend consulting with your electrician and gas services professional to explore options, associated costs, and the specific requirements for any necessary relocations. PG&E frequently updates their regulations; your electricians and plumbers should be up to speed regarding their latest rules and conflict resolutions related to electric and gas meters.
If undergrounding of overhead electrical lines is required, all other utilities should also be installed underground. Be sure to discuss this with your electrician to ensure proper coordination and accommodations for all utility services.
PG&E requires a separate meter for each dwelling unit, which is typically triggered by the assignment of a new address (necessary for both ADUs and JADUs). In the case of a JADU, which is not considered a separate dwelling unit, a new address may still lead to the requirement for a separate meter. The Energy Code mandates that provisions and capacity for an electric vehicle (EV) charger be included in newly constructed ADUs when parking spaces are provided. Additionally, the Energy Code specifies that any newly constructed ADU must be equipped with a Battery Energy Storage System or be prepared for future installation.
The installation of a new electrical meter is a lengthy process and should commence promptly upon permit issuance or sooner. Please coordinate with your electrician regarding the appropriate timing for your project. While some projects may not immediately attract PG&E attention, future inspections or visits could result in new meter requirements.
Please be aware of potential metering surprises, such as the spacing requirements for existing gas and electrical meters on the primary dwelling. PG&E requires a minimum clearance of 36 inches from the vent on the gas meter to the edge of the electrical panel. Certain situations may necessitate panel or vent relocation. We recommend consulting with your electrician and gas services professional to explore options, associated costs, and the specific requirements for any necessary relocations. PG&E frequently updates their regulations; your electricians and plumbers should be up to speed regarding their latest rules and conflict resolutions related to electric and gas meters.
If undergrounding of overhead electrical lines is required, all other utilities should also be installed underground. Be sure to discuss this with your electrician to ensure proper coordination and accommodations for all utility services.
Solar Requirements:
Newly constructed Accessory Dwelling Units (ADUs) are required by the California Energy Code to incorporate solar systems, excluding manufactured homes. This requirement applies to new, detached ADUs, although certain exceptions may be applicable based on factors such as size and shading. According to the California Energy Commission (CEC), solar systems can be installed either on the ADU itself or on the primary dwelling unit. ADUs that are built within existing spaces or as additions to existing homes—including detached additions such as conversions from non-residential to residential use—are not subject to this solar requirement. It is also advisable to explore local and federal credits and incentives, which can significantly offset the cost of installing solar systems.
Newly constructed Accessory Dwelling Units (ADUs) are required by the California Energy Code to incorporate solar systems, excluding manufactured homes. This requirement applies to new, detached ADUs, although certain exceptions may be applicable based on factors such as size and shading. According to the California Energy Commission (CEC), solar systems can be installed either on the ADU itself or on the primary dwelling unit. ADUs that are built within existing spaces or as additions to existing homes—including detached additions such as conversions from non-residential to residential use—are not subject to this solar requirement. It is also advisable to explore local and federal credits and incentives, which can significantly offset the cost of installing solar systems.
Parking:
Parking requirements for ADUs shall not exceed one parking space per unit or bedroom, whichever is less. These spaces may be provided as tandem parking on a driveway. Guest parking spaces shall not be required for ADUs under any circumstances. In addition, a local agency may not require off-street parking spaces to be replaced when a garage, carport, covered parking structure, or uncovered parking space is demolished in conjunction with the construction of an ADU or converted to an ADU. Local agencies should be flexible when siting parking for ADUs. Off-street parking spaces for the ADU shall be permitted in setback areas in locations determined by the local agency or through tandem parking unless specific findings are made otherwise based on specific site or regional topographical or fire and life safety conditions.
ADU's that are exempt from parking requirements:
Parking requirements for ADUs shall not exceed one parking space per unit or bedroom, whichever is less. These spaces may be provided as tandem parking on a driveway. Guest parking spaces shall not be required for ADUs under any circumstances. In addition, a local agency may not require off-street parking spaces to be replaced when a garage, carport, covered parking structure, or uncovered parking space is demolished in conjunction with the construction of an ADU or converted to an ADU. Local agencies should be flexible when siting parking for ADUs. Off-street parking spaces for the ADU shall be permitted in setback areas in locations determined by the local agency or through tandem parking unless specific findings are made otherwise based on specific site or regional topographical or fire and life safety conditions.
ADU's that are exempt from parking requirements:
- ADUs located within one-half mile walking distance of public transit.
- ADUs located within an architecturally and historically significant historic district.
- ADUs that are part of the proposed or existing primary residence or an accessory structure.
- When on-street parking permits are required but not offered to the occupant of the ADU.
- When there is a car share vehicle located within one block of the ADU.
- When a permit application for an ADU is submitted with a permit application to create a new single-family dwelling or a new multifamily dwelling on the same lot, provided that the ADU or the parcel satisfies any other criteria listed in Government Code section 66322, subdivision (a)(1)-(5).
Fire Sprinklers:
Installation of fire sprinklers shall not be required in ADUs or JADUs if sprinklers are not required for the existing primary residence. However, if any wall of a newly constructed detached ADU is more that 150-feet (measured in right angles around the structure) from the centerline of the street, sprinklers may be required for the ADU.
Installation of fire sprinklers shall not be required in ADUs or JADUs if sprinklers are not required for the existing primary residence. However, if any wall of a newly constructed detached ADU is more that 150-feet (measured in right angles around the structure) from the centerline of the street, sprinklers may be required for the ADU.
Conversion of Existing Structures:
Any conversions of unpermitted or illegal construction will need to adhere to current building, structural, and energy code standards. The existing foundation and framing must be assessed to ensure compliance with these standards. Most of the existing insulation will require replacement, which typically involves removing all existing drywall. Additionally, lighting and plumbing systems must meet current building and energy code requirements.
Any conversions of unpermitted or illegal construction will need to adhere to current building, structural, and energy code standards. The existing foundation and framing must be assessed to ensure compliance with these standards. Most of the existing insulation will require replacement, which typically involves removing all existing drywall. Additionally, lighting and plumbing systems must meet current building and energy code requirements.
Contact:
Office: Napa, CA
Hours: Weekdays 8:00AM to 5:00PM
Office: Napa, CA
Hours: Weekdays 8:00AM to 5:00PM