Some special zoning regulations apply to ADU construction in Huntington Beach. ADUs are allowed in residential areas. Each zone has different rules that govern the size and location of the ADU. The owner of the main house does not need to live in ADU. Renting is allowed.
The size of the ADU in Huntington Beach depends on the size of your plot. Low-sized ADUs can be made on small plots. Large ADUs are allowed on large plots. Different size limits have been set for single family and multi-family properties.
| Plot Size | Single-family (maximum floor area) | Duplex and multi-family (maximum floor area) |
| 4,000 | 1,000 sqft | 600 sqft |
| 6,500 | 1,300 sqft | 800 sqft |
| 9,000 | 1,600 sqft | 1,000 sqft |
| 14,000 | 2,200 sqft | 1,400 sqft |
| 18,000 | 2,800 sqft | 1,800 sqft |
The maximum height of the ADU in Huntington Beach should be less than the main house. The height of a single-storey ADU can be up to 16 feet. The maximum height for a two-storey ADU has been set at 24 feet. It is necessary to select the slope of the roof and the construction material according to these limits.
A limit has been set on the total construction area on the plot. The main house and the ADU together cannot occupy more than 50% of the area of the plot. This rule is important to maintain open space and greenery. The parking area is not included in this limitation.
Single-Family Properties:
Duplex and Multi-family Properties:
The exterior design of the ADU should match the main house. Choose the color, ceiling style, and building materials thoughtfully. Determine the location of windows and doors with privacy in mind. High quality finishing is essential on exterior walls.
A parking lot is mandatory for every ADU. This site can be in a garage or open space. Access to the parking lot should be easy. The parking requirement may be waived in certain circumstances. The parking area should be constructed as per the municipal norms.
It is necessary to leave the prescribed distance around the ADU. A distance of 20 feet in front, 10 feet on the back and 5 feet on the side is mandatory. These distances are essential for fire safety and privacy. There are different rules for corner plots.
The minimum plot size has been set for constructing ADUs in residential areas. ADUs can also be built on small plots. Different minimum sizes have been fixed for different zones. Prior permission from the Municipal Corporation is required.
| zone | Minimum plot area |
| R-18 | 4,500 sqft |
| R-9 | 7,000 sqft |
| R-6 | 9,500 sqft |
| R-4 | 14,500 sqft |
| R-2 | 19,500 sqft |
Separate electricity, water and sewer connections will have to be arranged for ADU. The connection can be obtained from the utility line of the main house. The meters should be separate. Get the connection work done by licensed plumbers and electricians only.
Get information about underground pipes and cables before laying a new utility line. All connections must be in accordance with the building code. Take prior permission from utility companies. Ensure repair facilities in case of emergency.
It is necessary to install smoke detectors and carbon monoxide alarms to prevent fire in ADU. The way to the emergency exit should be clear. Arrange a fire extinguisher. Electrical wiring and gas line must be safe.
ADU in Huntington Beach is allowed to rent short-term. The rental period should not be less than 30 days. Commercial activities can also be carried out at ADU. But these activities should not disturb the neighbours. A license is required.
ADUs must be constructed in accordance with California building codes. Building materials should be of high quality. All electrical and plumbing works must be in compliance with standards. Ensure regular inspections.
All necessary permits must be obtained before building an ADU in Huntington Beach. Submit a detailed plan and documentation for the permit. The procedure can take 2-3 months. Stay in touch with the Municipal Corporation for regular updates.
| Permit Type | cost |
| Building Permits | ₹1,800 – ₹4,500 |
| Electrical Permit | ₹200 – ₹450 |
| Plumbing Permit | ₹180 – ₹350 |
| Mechanical Permit | ₹130 – ₹250 |
| Demolition Permit | ₹80 – ₹180 |
| Landscaping Permit | ₹40 – ₹90 |
The property condition should be good for the ADU. Soil testing and groundwater level information are essential. Follow special construction standards in areas prone to floods or earthquakes. Separate permission will be required for felling of trees.
A car parking lot is mandatory for ADUs. The parking lot should be paved and level. Keep the access road to the parking area clean. In case the garage is converted into an ADU, alternative parking will have to be arranged.
The distance of the ADU from the road side should be at least 20 feet. Setbacks are necessary on both roads in the corner plot. ADUs are not allowed in the front yard. Make the setback area beautiful with landscaping.
A distance of 5 feet on the side and 10 feet on the back is mandatory. Take care of the neighbor’s privacy. You can plant trees in the setback area. Keep the way open for emergency vehicles.
Open space should remain even after ADU. Leave 30% of the back yard empty. Keep space for children to play and garden. Make proper drainage arrangements.
ADUs can be built on all residential properties in Huntington Beach. ADUs are allowed in single family, duplex and multi-family buildings. The size of the plot should exceed the minimum requirement. The existing building should be in safe condition.
Additional regulations apply in special areas such as historic districts or coastal zones. Special care has to be taken in the design and construction of ADUs in such places. Check all requirements before obtaining a permit.
The junior ADU consists of a small unit of up to 500 square feet inside the main home. It should have small kitchen and bathroom facilities. A door can be shared with the main house. Junior ADUs do not require separate parking.
The Huntington Beach Municipal Corporation has pre-approved some standard ADU designs. Using these designs speeds up the permit process. Various size and layout options are available in the pre-approved design. These can be changed slightly according to your need.
The manufacturing of pre-approved ADUs will also be as per the standard procedure. All rules of inspection and quality control will apply. These designs are preferred for cost and time saving. Our team will help you choose the appropriate option.
ADU Builders CA provides full cooperation in your ADU construction. Our expert team will guide you through every step from design to construction. Contact us today and take the first step towards realizing the ADU of your dreams.
Fire sprinklers are only required if the primary dwelling also has them.
ADUs typically require a minimum setback of 4 feet from property lines.
Separate utility connections are optional but not mandatory for most ADUs.
The checklist includes design review, site plans, structural plans, permits, and financing.
You need site plans, floor plans, construction details, and a permit application.
Inspections typically include foundation, framing, plumbing, electrical, and final review.
Work with licensed professionals to design and construct your ADU to code.
You may need to revise and resubmit plans to the Huntington Beach planning office.
Submit complete and accurate documents and work with professionals to avoid delays.
ADUs under 750 sq. ft. are exempt from impact fees.
Yes, it includes checking structure, utilities, and obtaining conversion permits.
Yes, ADUs must meet height, size, and setback requirements, and their design should complement the primary dwelling.
Yes, but you need to ensure the ADU fits within allowable lot coverage and setback rules.
ADUs must comply with California Building Codes, including foundation, framing, insulation, plumbing, and electrical requirements.
Yes, ADUs must comply with California Energy Code (Title 24) and include energy-efficient windows, insulation, and appliances.
You must submit a revised plan to the Huntington Beach Building Department and may incur additional fees or inspections.
Yes, ADUs near high-noise areas (e.g., busy roads) must include soundproofing measures such as double-glazed windows.
Yes, you can appeal to the city’s Planning Commission or seek adjustments to meet requirements.
Lot coverage varies by zoning but generally allows for up to 50% of the lot to be developed, including the primary dwelling and ADU.
