Campbell homeowners looking to add accessory dwelling units to their property will need to take a second look at new city rules after the start of the New Year.

The city’s planning commission is recommending the city council on Dec. 6 implement changes to the city’s ordinance regarding accessory dwelling units—commonly referred to as granny units or in-law flats—to be consistent with recently passed state legislation that goes into effect Jan. 1.

The new rules at the state and local level seek to relax rules regarding the units. Local municipalities need to create their own ordinances, otherwise the state rules will automatically be adopted locally, according to city planner Daniel Fama.

Campbell’s proposed ordinance addresses the different types of dwelling units, their maximum size and parking requirements. The ordinance deals with three types of accessory units: interior units, which are created within an existing house, attached units that are additions made to an existing house and detached units that are completely separate structures.

According to city staff, state legislation will allow units to increase in size.

“Under the state law…the maximum size will go up to 1,200 square feet,” Fama told the planning commission, adding that the city’s minimum size will increase from 640 square feet to 700 square feet under the proposed ordinance.

Fama added that a 1,200-square-foot unit can be built under the proposed ordinance if the property lot size is 15,000 square feet or larger. Attached and interior units cannot be more than 50 percent of the main residence’s square footage.

Attached and interior units are restricted to the ground floor of the main residence, while a detached unit will be limited to 14 feet in height to maintain privacy for surrounding residents, according to Fama.

Under the city’s current ordinance, two parking spaces are required when a unit is built. However, the proposed ordinance would require only one parking space per bedroom for an attached or detached unit. If a unit is located a half-mile from a light rail station, within a historic district, within an area under a parking permit program, or a block away from a vehicle sharing program such as Zipcar, then parking is not required, according to city staff.

If a homeowner plans to convert their garage into a granny unit, it must be the same size as it was in its original garage form.

Rules have also been relaxed for sprinkler systems for interior units.

“If you were to do an interior unit within an existing building, you would not have to do install sprinklers, which historically has been a burden for many homeowners,” Fama said. “However, if you were to do attached unit or a detached unit, you would need the sprinkler at the new unit.”

Under the proposed ordinance, homeowners are allowed to rent out only one unit—either the accessory unit or main residence—at a time. However, leases for short-term rentals for less than 30 days are prohibited.