Special zoning regulations apply to ADU construction in the City of Hawthorne. It is necessary to follow certain standards to make ADUs in residential areas. ADUs are allowed in residential zones but their size and height should be within the prescribed limit. ADUs cannot be made in commercial and mixed-use zones.
The size of the ADU depends on the size of the plot and the following limitations apply:
| Lot Size | Single-Family (Maximum Floor Area Allowed) | Duplex and Multi-Family (Maximum Floor Area Allowed) |
| 6,000 | 1,400 sq ft | 900 sq ft |
| 8,500 | 1,700 sq ft | 1,100 sq ft |
| 11,000 | 2,000 sq ft | 1,400 sq ft |
| 16,000 | 2,600 sq ft | 1,800 sq ft |
| 21,000 | 3,200 sq ft | 2,200 sq ft |
The maximum height of the ADU in Hawthorne should be less than the main house. The height of a one-storey ADU should not exceed fifteen feet. The maximum height of a two-story ADU can be up to twenty-five feet. The slope and design of the roof should conform to local building codes.
The total coverage of the plot from the construction of the ADU should not exceed fifty percent. The total area of existing houses and new ADUs needs to be carefully measured. It is necessary to leave enough space for open space and greenery. This rule is very important for drainage and aeration.
Single-Family Homes:
Duplexes and Multi-family:
The exterior design of the ADU should match the main house and look attractive. The material used on exterior walls should be of quality. The design of windows and doors needs to be modern and safe. The color and texture should be selected keeping in mind the buildings in the neighborhood.
There should be a provision of at least one parking place for every ADU. Parking lots can be built in front or next to the house. In case the garage is converted into an ADU, alternative parking will have to be arranged. Roadside parking is allowed only under certain circumstances.
The minimum distance of the ADU from the main road should be twenty feet. A buffer zone of five feet from the neighbor’s property is mandatory. A distance of at least ten feet must be kept in the back part. The measurement of the setback is done from the outer wall of the ADU.
| Zone | Minimum Lot Area |
| R-22 | 5,500 sq. ft. |
| R-12 | 8,000 sq. ft. |
| R-8 | 11,500 sq. ft. |
| R-6 | 16,500 sq. ft. |
| R-3 | 21,500 sq. ft. |
Separate electricity, water and sewer connections must be arranged for ADUs. New lines are laid to the ADU from the connection to the main house. It is necessary to check the capacity of the water meter. The capacity of the transformer may have to be increased if the load of electricity increases.
The connection of the sewer line is connected directly to the main line. If the gas line is needed, then a separate permit will have to be obtained for it. All connections must be established as per local body rules. It is necessary to hire specialist contractors for utility connections.
Many special provisions must be made in ADU for fire safety. It is mandatory to install smoke detectors and carbon monoxide alarms. There should be at least one additional door for the emergency exit. The windows should be large enough to be exited in an emergency.
Special permits are required to rent short-term ADUs in Hawthorne. ADU cannot be given to the tenant for less than thirty days. Separate permission will have to be taken to run a home office or small business. Business activities should not disturb neighbours.
It is mandatory for ADU construction in Hawthorne to follow California building codes. The structure of the building should conform to earthquake resistant standards. Electrical and plumbing works should be done only by licensed contractors. The quality of building materials must conform to the regulations.
All necessary permits must be obtained before the construction of the ADU. Detailed maps and documents must be submitted for the permit. Construction work can be started only after inspection. The permit has a validity of two years.
| Permit Type | Cost |
| Building Permit | $2,500 – $5,500 |
| Electrical Permit | $300 – $600 |
| Plumbing Permit | $250 – $450 |
| Mechanical Permit | $200 – $400 |
| Demolition Permit | $150 – $300 |
| Landscaping Permit | $100 – $200 |
To make an ADU on the property, some basic requirements must be fulfilled. The slope of the ground should not exceed fifteen percent. There should be no legal dispute over the land. Adequate space should be available for parking and open space.
The distance of the ADU from the main road should not be less than twenty feet. Space will have to be left for the lawn or garden in front. Additional space will have to be arranged for garage or parking. No permanent construction can be done in the setback.
The side setback should be at least five feet. A setback of ten feet at the rear is mandatory. It is important to take care of the privacy of the neighbor. Trees and plants can be planted in the setback area.
The area of open space should be thirty percent of the total area of the plot. In the back part it is necessary to leave enough space for the garden. There should be a safe place for children to play. It is necessary to have a proper arrangement for the drainage of rainwater.
Properties eligible for ADU construction in Hawthorne must meet certain criteria. ADU can be made in all single-family houses located in the residential area. The plot size should exceed the minimum requirements. The existing building must be stable and safe.
The land should be used for residential purposes only. ADU is not allowed in commercial or industrial property. There should not be any legal dispute on the plot. All outstanding taxes and bills must be paid.
Multifamily properties
Junior ADU is built inside the main house and its area should not exceed five hundred square feet. Compact kitchenettes can be arranged for the kitchen. The bathroom can be shared with the main house. The entrance door should be separate and the inner door can also be placed.
The City of Hawthorne has already approved some standard ADU designs. Using these pre-approved designs speeds up the permit process. Small changes can be made to the standard design as per requirement. Using these designs saves time and money.
ADU Builders CA also has many pre-approved designs available. Our team will help you choose the most suitable design according to your need. Our designs conform to all regulations and standards. Modern facilities have been included in them.
This is the best time to start building your ADU in Hawthorne. ADU Builders CA will assist you throughout the process. Our expert team will work with you to realize the ADU of your dreams. Contact us today and increase the value of your property.
Start by confirming zoning eligibility, creating design plans, and applying for permits.
Required documents include site plans, structural drawings, and energy compliance reports.
Yes, detailed architectural plans are required for permit approval.
A soil report may be required, depending on the location and scope of the project.
Yes, ADUs must meet California Title 24 energy standards.
Construction timelines vary but generally range from 6 to 12 months, depending on the project size and complexity.
