Research report2024San Diego

Not So Gentle Density: An Early Assessment of the San Diego Bonus ADU Program

California ADU researchers

Main finding

The bonus program enabled small multifamily-style infill, but utility costs, financing, geography, and implementation capacity constrained early delivery.

40% of proposed bonus ADUs were in Moderate Resource areas, versus 25% of all ADUs

Most important limitation

Most observations were proposed or permitted rather than completed; overlapping state and local reforms prevent a citywide causal conclusion.

From the publication

Study chart · redrawn

Most proposals remained modest, while a smaller group used the program for substantially larger infill projects.

REDRAWN FROM STUDY DATAFigure 6 · Proposed bonus-ADU projects by units per project

Figure 6 · Proposed bonus-ADU projects by units per project. Values digitized from Figure 6 in the archived publication; minor reading error is possible.
Total proposed units per project	Bonus-program projects
2	42
3	37
4	23
5	15
6	10
7	6
8	4
9	2
10+	3

How this study is used

Reference

California ADU researchers (2024). “Not So Gentle Density: An Early Assessment of the San Diego Bonus ADU Program.”