“Ministerial processing” or “ministerial approval” is a streamlined permit process for development approval involving little or no personal judgment by the public official. As opposed to "Discretionary review process" that allows for public hearings which brings a lot of uncertainty and months or years long approval process, Ministerial approval is as short as 90 days. This short and streamlined approval process helped the new SB-9 law, which allows for more units on single-family home zoned areas, to be realistically possible to apply even in tough neighborhoods.
The framework the Ministerial approval was originally set by SB 35 and issued with the goal to create more affordable housing. This bill requires cities and counties to streamline review and approval of eligible affordable housing projects through a ministerial approval process, exempting such projects from environmental review under the California Environmental Quality Act (“CEQA”). This process does not allow public hearings to consider the merits of the project; rather, only design review or public oversight of the development is allowed, which must be objective and strictly focused on assessing compliance with criteria required for streamlined projects as well as objective design review of the project (Section 65913.4(c)(1). Depending on the number of housing units proposed in the project, the jurisdiction has only a short timeframe within which to review the application to determine if it is eligible for processing under SB 35 (between 60-90 days). If it is determined that the project is eligible, SB 35 specifies the timeframes within which the jurisdiction has to make a final decision on the application (between 90-180 days).
Now, if you want to make an addition to your house in order to add one more unit or you want to split your lot to make a new house on that lot, you can choose to take the streamlined Ministerial approval process and get the permits in just 90 days. No need to worry about your neighbor willingness to let you build. You just have to find out how large a house could be on your lot and your finances. You could hire an architect to find our the size of the house on (each) lot which is approx. $2,000 or request a development opportunity analysis that starts from $199. In regards to financing your project, many cities in California offer financial support with programs for affordable housing. For instance, San Francisco gives residents significant down payment to purchase a house in the city. Great financing programs and free money available for California residents who want to build an ADU on the property.