Here is the City of San Jose brochure link for "in-law units".
From the brochure - Highlights:
MINIMUM LOT SIZE
â€¢ Attached unit â€“ 6,000 sq. ft. lotâ€“ an attached unit is structurally
connected to the main house
â€¢ Detached unit â€“ 8,000 sq. ft. lotâ€“the unit stands independent
of the main house (minimum 6 feet from the main house)
MAXIMUM UNIT SIZE Lot 9,000 sq. ft. or less - 600 sq. ft.
Lot 9,001 - 10,000 sq. ft. - 650 sq. ft.
Lot 10,001 sq. ft. or greater - 700 sq. ft.
MAXIMUM NUMBER OF BEDROOMS One
MAXIMUM BEDROOM SIZE 400 sq. ft.
MAXIMUM NUMBER OF BATHROOMS One
MAXIMUM CLOSET/STORAGE SIZE 60 sq. ft.
REQUIRED PARKING One open or covered parking space
outside of front and side setbacks (this is in addition to those
spaces required for the main house)
â€¢ Attached unit â€“ Same setback requirements as main house
â€¢ Detached unit â€“ Same setback requirements as main house
â€¢ Must be behind the main house
â€¢ Minimum of six feet from existing structures
â€¢ Maximum height = 18 feet. Average height = 14 feet
â€¢ Maximum 40% rear yard coverage for total of secondary
unit, accessory buildings and structures
â€¢ Exterior materials must match main house
â€¢ Roof pitch and form must match main house
â€¢ Front door elevation must be different from the front door to
â€¢ Windows shall not have views into adjacent residences or
backyards of residential properties
Hope this helps.