San Diego detached ADUs lag from permit to completion

A new SnapADU analysis of City of San Diego permit data finds that about 74 of every 100 detached ADU projects receive permits, but only 43 finish final inspection within three years. The report highlights where housing projects stall and suggests that earlier planning could help more units get built.

Why it matters: - The data shows a gap between ADU demand, permitting and completed housing in San Diego. - Tracking final inspections alongside applications and permits gives policymakers a clearer read on how many units actually reach the market. - The findings point to potential bottlenecks that may be slowing new housing delivery, from design changes to utility and site constraints.

What happened: - SnapADU analyzed public records from the City of San Diego Development Services Department to track detached new-construction ADU projects from submission through permit issuance and final inspection. - The report, "San Diego ADU Permit Data: How Many ADUs Actually Get Built? (2020 to 2026)," was updated through June 2026. - The analysis focused on projects submitted between 2021 and early 2023 so each cohort had a full 36 months of history. - For every 100 detached accessory dwelling unit projects submitted to the City of San Diego, about 74 received permits and 43 reached final inspection within three years.

The details: - Detached new construction made up 45% of the roughly 10,000 ADU and JADU applications submitted from 2021 through 2025, making it the largest project category. - 26% of submitted detached new ADU projects did not receive a permit within three years. - 24% of submitted projects reached final inspection within two years. - That share rose to 43% within three years. - Completed projects took an average of 23.8 months from submission to final inspection. - That timing excludes feasibility work, surveys, utility planning and design completed before submission. - City public records show whether a project advanced, but they do not identify why a project stalled. - Potential causes include owner decisions, redesign during plan review, unexpected utility or site requirements, fire and brush management constraints, construction costs and financing. - SnapADU also reviewed its own San Diego projects within the same public dataset. - Among SnapADU’s 43 projects, 69% reached final inspection within two years and 90% within three years. - SnapADU’s average time from submission to completion was 17.4 months, about six months faster than the citywide average for completed detached ADUs. - SnapADU consulted with the City of San Diego’s Development Services Business Intelligence team to verify how the public dashboard and permit records are structured and counted. - SnapADU independently developed the project classifications and completion analysis. - The report says the full methodology and limitations are detailed in the study.

Between the lines: - The results suggest that some of the delay may be happening before or during early project planning, not just in city review. - Whitney Hill, CEO and co-founder of SnapADU, said earlier feasibility work, utility review and project scoping may help projects move more smoothly through construction. - Hill also said better visibility into final inspections can help cities, designers, builders, lenders and homeowners understand where projects are getting stuck. - The findings do not prove a single cause for stalled projects, but they do show that approvals alone do not equal completed homes.

What's next: - The report recommends that cities and housing leaders track final inspections along with applications and permit issuance. - Following project cohorts over time could help distinguish plan review delays from other barriers. - Better cohort tracking could help cities and industry partners target fixes more effectively. - SnapADU says the approach could help more projects move from plans to actual homes.

The bottom line: - San Diego has a meaningful ADU pipeline, but a sizable share of detached projects never make it from submission to finished housing within three years.