San Pablo has produced a handout describing its ADU policies

Extract:

The following are the requirements for Accessory Dwelling Units:
o Only allowed in the R-1 zoning district in conjunction with single family dwellings
o Only allowed on lots that are greater than 5,000 square feet in size.
o Only one ADU allowed per parcel.
o Are a maximum of 700 square feet. ADUs in excess of 700 square feet may be approved by a conditional use permit, but may not exceed 1200 feet.
o No ADU, either attached or detached can exceed 50 percent of size of the living area of the primary dwelling.
o The City does not require you to install a new or separate utility connection directly between the ADU and the utility, unless the utility connection is required by the utility provider. You may voluntarily install a new or separate utility connection.
o There are no parking requirements for the ADU over the parking requirements of the home within the city of San Pablo. However, if an ADU is formed by the conversion of an existing garage the parking spaces must be replaced so that the house has the required parking.

Lot Coverage: No more than 45 percent, including all structures on the property.

more….

See full handout