You want to make a profit??? Let Imperial Design and Remodel build a second home on your lot and lower your mortgage at the same time! New laws remove the restrictions on building a second home on you lot for rental purposes.

If you’ve ever considered adding a second unit to your home, now’s the time to get serious. Secondary units—colloquially referred to as granny units or in-law units, and more formally described as Accessory Dwelling Units (ADUs)—are easier, and less costly, to build than ever before. New state-wide legislation reduces restrictions and streamlines the permitting process.

As of January 1, 2017, all local governments are required to comply with these new ordinances. Some cities are choosing to reduce requirements further in the hopes of spurring housing development.

The benefits of secondary units are many. In addition to increasing housing options at city and county levels, a granny unit gives homeowners the opportunity for extra monthly income. It’s also greatly helpful for multi-generational families that need extra space for adult children or those looking for an aging-in-place solution for elderly parents.

Second Home/Granny Unit Types

To be a legitimate ADU, a granny unit must provide a separate independent living area, including kitchen and bathroom, for one or more person. While an ADU cannot be sold separately from the existing main living residence, it is eligible as a rental.

Detached: A detached unit is, as it sounds, entirely detached from the property’s main residence. Unless built into an existing detached garage, a detached unit has specific setback requirements. It will also necessitate new utility connections. But the law requires that fees must be proportionate to the size of the unit. Different cities will have specific limitations. In San Jose, a newly built detached unit must be a single story, no more than 18 feet.

Attached: An attached unit is indeed attached to the property’s primary residence, meaning the two share a wall or significant roof structure. As such, an attached granny unit must adhere to typical zoning limitations, although some cities may have their own requirements. Campbell restricts attached units (and repurposed existing space units) to ground level.

Repurposed Existing Space: This is a secondary unit that’s built within an existing space in a primary residence, such as a bonus room converted to a studio. Local governments cannot require new or separate utility connections for ADUs within an existing structure.

ADU Standards

The state-wide legislation is currently the minimum requirement that must be adopted by all cities. Within the law, local governments have the authority to enforce land size minimums for secondary unit approvals, as well as ADU size minimums and maximums. In addition to complying with a city’s size limitations, a secondary unit must meet the following standards.

  • The unit is not intended for sale and may be rented.
  • The lot is zoned for single-family or multifamily use.
  • The lot contains an existing single-family dwelling.
  • The ADU is either attached to the existing dwelling and located within the living area of the existing dwelling or detached from the existing dwelling and located on the same lot as the existing dwelling.
  • The increased floor area of an attached ADU shall not exceed 30 percent of the existing living area.
    The total area of floorspace for a detached ADU shall not exceed 1,200 square feet.
  • Requirements relating to height, setback, lot coverage, architectural review, site plan review, fees, charges, and other zoning requirements generally applicable to residential construction in the zone in which the property is located.
  • Local building code requirements which apply to detached dwellings, as appropriate.
  • Approval by the local health officer where a private sewage disposal system is being used, if required.


A significant change required by the new legislation also addresses parking. Cities cannot require more than one space per ADU bedroom or unit. If building the new unit removes existing parking, different cities may have replacement requirements. However, the new law stipulates that approved off-street replacement options should be flexible enough to accommodate tandem or uncovered parking.

Parking requirements are not mandatory if the unit is:

  • within half a mile of public transportation, including a bus stop or train depot, or a half block from a car share;
  • located in an “architecturally or historically significant district”;
  • part of an existing primary residence; or
  • in a neighborhood with permitted street parking that’s unavailable to the resident of the unit.

Alarmed by the lingo and so many city-specific requirements? Don’t be! Imperial Design and Remodel knows building ordinances in and out for Southern California. Our experienced design team will help you determine the ideal secondary unit that meets your needs, while our build team ensures that we satisfy all city requirements.