New laws allow for more housing in county, Sonoma Valley
The state’s answer to the housing crisis makes it easier for homeowners to build granny units and convert unused bedrooms for rental use. But in the Sonoma Valley, the prevalence of wells and septic systems mean the process is still far from simple.
The most significant change in the state laws that took effect Jan. 1 is that cities and counties are now prevented from establishing a minimum lot size before allowing granny units, technically called Auxiliary Dwelling units (ADU). Those ADUs can also be larger than before. The County of Sonoma previously required at least one acre to build an ADU and limited the ADUs to as small as 640 square feet. Now an ADU of up to 1,200 square feet can be permitted on any property, regardless of parcel size.
The additional challenge for properties with septic systems starts with defining where the existing underground leach field is located. You can’t build a new structure on top of, or within eight feet of leach lines. If you don’t have plans showing the current system, you’ll have to pay an engineering firm to map it. For ADUs, the county also requires that the existing septic system meets current requirements. Many don’t, according to Adobe Engineering’s Steve Brown, who says there are a variety of remedies. “You could have to justify a new replacement area, or maybe you need a new basic system just for the ADU for around $20,000, or the county could send you down a path that would require a new system for the house and the ADU for $40-$80,000.” The best-case scenario, Brown says, is the county allows you to “trade” a bedroom from your house to the ADU. This would require actions like removing the closet and entry door from an existing bedroom.
The next potential trip wire is water, if you have a private well. Most of Kenwood and Glen Ellen are in a low groundwater zone, so a well test is required to demonstrate a minimum water yield. The test must be conducted between mid-July and Oct. 1.
The county also requires at least a 4-foot setback between the ADU and side and rear property lines. The setback from the front of the property depends upon its zoning. For example, in the RR and R1 zones most popular in Kenwood village and “central” Glen Ellen, the regulations say it’s 20 feet, however “no structure shall be located closer than forty-five feet (45’) to the centerline of any public road.” That means your front setback is more than 20 feet if your street is less than 50 feet wide.
Auxiliary dwelling units must have permanent provisions for living, sleeping, eating, cooking and sanitation. By the terms of the new state laws, the county must process ADU applications with a minimum of delay. “The building permit fees are $6,000-$12,000, depending upon the size, and we have 60 days to approve or deny,” says county planner Nina Bellucci. “We want to build more ADUs because they’re a cost-effective way to increase our housing.”
The new regulations also allow a “Junior ADU” on each property. The JADU’s maximum size is 500 square feet, and it may include an efficiency kitchen. The intent is to enable homeowners to turn existing unused bedrooms into separate dwelling units simply by adding an exterior door. JADUs may not be used for vacation rental.
These new state laws override homeowners’ associations’ regulation of ADUs and JADUs, suggesting there may be battles ahead in Oakmont, for example.