Accessory Dwelling Units (ADUs) are attached or detached residential dwelling units that provide complete independent living facilities and are located on a lot with a proposed or existing primary residence. ADUs can be converted units or new construction.  Generally, ADUs are a minimum of 150 square feet and a maximum of 1,000 square feet. 

Junior Accessory Dwelling Units (JADUs) are smaller units with a limited size of 500 square feet. JADUs are contained entirely within an existing or proposed single-family structure. Whereas all facilities are separate for ADUs, JADUs permit common sanitation facilities.

The State of California has created basic rules for ADUs—called “Streamlined Permit Standards”—that every city must allow. These standards are designed to reduce local barriers and simplify the approval process.  In addition to the State’s standards, Monrovia also offers an alternative option called the “Alternative Local Standards.” These are local development standards that give homeowners more flexibility when their project doesn’t qualify under the State’s streamlined rules.  The rules that apply to your property will depend on whether it is developed—or proposed to be developed—with a single-family dwelling or a multi-family structure.

Using the Streamlined Permit Standards, lots with a detached Single-family Dwelling are permitted three types of ADUs, one converted ADU (either attached or detached), one new construction ADU (detached only) and one JADU.

All properties with a multi-family dwelling structure will use the Streamlined Permit Standards. Lots with a Multi-Family Dwelling Structure can have multiple converted ADUs if the quantity does not exceed 25% of the existing multi-family dwelling units. You can have up to eight (8) detached ADUs, so long as the quantity of ADUs does not exceed the number of existing units on the lot with a multi-family dwelling structure.

All properties with a multi-family dwelling structure will use the Streamlined Permit Standards. Lots with a multi-family dwelling structure can have multiple converted ADUs if the quantity does not exceed 25% of the existing multi-family dwelling units. In addition, you can have up to two detached ADUs.

Because none of the units are attached to each other, there is no multi-family dwelling structure, and the property is required to utilize the standards for a Single-Family Dwelling developed lot. The type and number of detached ADUs permitted are based on the current or proposed development on a lot, regardless of the zoning district. For instance, a multi-family zoned lot (RM, RH, etc.) with only a single-family structure would be subject to the limitations applicable to lots with single-family dwellings and not subject to the limitations applicable to lots with multi-family dwellings.

As the dwellings are detached from one another, the lot is subject to the allowances applicable to single-family developed lots. State law allows a maximum of three ADU types per lot, two ADUs and one JADU, regardless of the number of detached single-family dwellings. In this instance, even though there are two single-family dwellings, the property would only be permitted three ADU types, and each single-family dwelling is not permitted three additional units.

The allowed height limit doesn’t change if the ADU is built above a detached garage. Height is measured from the exterior finished grade and the detached garage with ADU above shall comply with the applicable height limit for the detached ADU (16 feet, 18 feet or, 20 feet—depending on the lot’s location and development). ADUs proposed over an attached garage would be subject to the height limitations for an attached ADU.

State law prohibits the establishment of a front yard setback requirement as it relates to ADU development and related mechanical equipment.

Parking can only be required for newly constructed ADUs that are greater than 800 square feet and not within ½ mile of any public transit stop, which includes any public bus stop.

The City does not currently have a High Quality Transit Corridor within its limits. A “High-Quality Transit Corridor” refers to any street with fixed route bus service with service intervals no longer than 15 minutes during peak commute hours.

The City does have one Major Transit Stop which is the Metro Rail Station. Proximity to a Major Transit Stop provides greater height limit allowances.