How Long Do ADU Permits Last in San Diego?

If you’re building an accessory dwelling unit (ADU) in the City of San Diego, one question often comes up once plans are approved:

How long do we actually have before we need to start construction?

Sometimes homeowners want to wait for the right moment. Maybe a family member plans to move in later. Maybe ADU financing is still being finalized. Or maybe you simply want the permit ready but prefer to delay construction. The good news is that San Diego’s rules provide some flexibility. But there are several timelines involved, and they are easy to misunderstand. Here is how it works.

If Your Permit Is “Ready to Issue,” Is There a Deadline to Pay?

Once the city finishes plan review, your project enters a status called Ready to Issue. At this stage, the city has approved the plans and is waiting for the permit fees to be paid. If you’re curious what those fees typically include, we break them down in our guide to ADU permit fees in San Diego. The City of San Diego does not publish a strict deadline for paying these fees. In practice, the permit can remain in Ready to Issue status for quite some time.

However, the permit application itself can expire if nothing happens for too long. Per City of San Diego Information Bulletin 119, a permit application may be closed if two years have elapsed since the date the application was deemed complete and the applicant has not requested that the building permit be issued.

In other words:

1. There is usually no short-term deadline to pay
2. But you generally cannot leave the project inactive for years

After the Permit Is Issued, When Must Construction Start?

Once the permit is paid and officially issued, a new clock starts. Under City of San Diego Information Bulletin 117, a building permit must be utilized within one year. In the city’s terminology, “utilized” means performing real construction work and calling for a qualifying inspection.

Examples of qualifying inspections include:

1. Foundation inspection
2. Under-slab plumbing inspection
3. Framing inspection

Administrative items like preconstruction meetings or paperwork reviews do not count. If no qualifying inspection occurs within one year, the permit can become void unless an extension is approved.

Once Construction Starts, How Long Can Work Pause?

After construction begins, another rule comes into play. Under California Building Code Section 105.5, work cannot stop for more than 180 days. In practice, this means the project must have at least one inspection every 180 days to keep the permit active. If work stops longer than that, the permit can expire unless the city grants an extension.

This rule exists to prevent projects from sitting partially built for long periods.

What Is the Overall Life of an ADU Permit?

Even if work continues steadily, permits are not indefinite. Under San Diego Municipal Code Section 129.0218, building permits for residential construction, including ADUs, typically expire three years after issuance if the project has not reached final inspection approval.

That means your project timeline usually looks like this:

1. 1 year to start construction after permit issuance
2. No more than 180 days between inspections once work begins
3. 3 years total to complete construction and receive final approval

ADU Permit Timeline in San Diego

If you’re wondering how long construction itself usually takes once permits are issued, see our guide on how long it takes to build an ADU in San Diego.

Can You Request Permit Extensions?

Yes. The City of San Diego typically allows 180-day extensions, provided:

1. The request is submitted before the permit expires
2. The project still complies with applicable building codes

Extensions are not automatic, but they are commonly granted when projects are actively progressing or experiencing reasonable delays.

A Common Scenario For Extending an ADU Permit

Sometimes homeowners intentionally delay construction. For example, we occasionally see situations where a family member plans to move into the ADU in the future. Rather than rushing into construction, homeowners may choose to:

1. Complete the design and permitting now
2. Pay for the permit later
3. Begin construction closer to the time the unit will actually be needed

This approach can work well as long as the permit timing rules above are understood and planned for.

Why ADU Permit Timing Strategy Matters

Many homeowners assume the moment a permit is approved, construction must start immediately. That is not always the case. However, understanding the timing rules is important because delays can create unexpected complications, including:

1. Permit expiration
2. Re-review under newer building codes
3. Additional permit fees
4. Restarting parts of the approval process

When planning an ADU project, a builder experienced with San Diego’s permitting process can help you structure the timing in a way that fits your goals. If you’re currently looking for a builder, our guide on How to Choose the Right ADU Company could be a helpful read.

The Bottom Line

For ADU projects in the City of San Diego:

1. Permit applications may close if inactive for two years before issuance
2. Once issued, construction must start within one year
3. Inspections must occur at least every 180 days once work begins
4. Projects typically must reach final approval within three years of permit issuance

Understanding these timelines helps homeowners plan their ADU project without unnecessary stress or surprises.

If you are considering building an ADU in San Diego and want help navigating the design, permitting, and construction process, our team at SnapADU specializes exclusively in ADUs and can guide you through every step. Contact our team to set up a complimentary discovery meeting.

Frequently Asked Questions