Here is a map of the parts of #Berkeley that the Middle Housing zoning change apply to - PDF is at https://berkeleyca.gov/sites/default/files/documents/Middle-Housing-Zoning-Map.pdf
The full text of the Middle Housing ordinance is at https://berkeleyca.gov/sites/default/files/documents/2025-07-08%20Item%20A%20Ordinance%207978.pdf
The new zoning allows 3 story buildings (this can be increased by Density Bonus).
State laws that allow additional homes:
Affordable Housing Density Bonus
🏠 Up to 100% more units if some are for low/middle income
https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=65915&lawCode=GOV
Accessory Dwelling Unit (ADU) law
🏠 Existing building can increase number of units by up to 25% by converting garages, storage, etc.
🏠 Can add up to 8 detached ADUs
https://www.hcd.ca.gov/policy-and-research/accessory-dwelling-units
Of course, not everyone will build to the maximum density. There's no requirement to do anything at all, people are free to keep their house as-is as a single family house. In other cases, a lower-density development may make more sense personally or financially. Let's look at some examples.
2/