How Long Does It Take To Build an ADU?

You’ve decided a backyard unit makes sense for your property, and now you want a project completion date on the calendar. That’s harder to pin down than most homeowners expect, because ADU construction in Murrieta, CA, involves several phases, each with its own timeline.

So, how long does it take to build an ADU? Builders Innovation Group will walk you through each phase so you know where the time goes.

Breaking Down the Three Main Phases

The project has three stages, each with a range rather than a fixed timeline. Your lot’s condition and your city’s regulations both play a role in shaping the schedule.

Here’s the typical ADU construction timeline:

1. Design and planning: Two to five months, depending on whether you pick a standard plan or go custom
2. Permitting and plan check: Three to nine months, driven mostly by your city’s review speed
3. Construction: Five to 10 months, based on unit size and site conditions

The design stage moves faster when you respond quickly to your team. Every week spent deciding on a floor plan pushes everything else back. Reading up on things to consider before adding an ADU helps you avoid surprises and delays later.

Why Permitting Takes the Longest Time 

The permit approval process is usually the biggest variable in the schedule. Cities review project plans against zoning and building codes and may issue corrections.

Second-round reviews are normal, not a sign of a mistake. Codes leave room for interpretation, and every property has quirks a reviewer needs to check.

Coastal areas and neighborhoods with a homeowners’ association add more steps. Submitting project plans to your HOA at the same time you submit to the city keeps those tracks running in parallel.

What Happens Once Building Starts?

If you’re wondering how long it takes to build an ADU once shovels are in the ground, the answer depends heavily on your lot. Site preparation covers grading and utility work. Rough ground can add weeks before framing even begins.

The construction phase then moves through foundation work, framing, rough trades, and interior finishes. Larger or two-story units take longer because more trades have to be scheduled.

Common Sources of Delay

A few issues push timelines out more than others. Watch for these:

• Utility upgrades: Older electrical panels or water lines often require work before an ADU can be connected.
• Material lead times: Custom windows and doors can hold up an otherwise ready build.
• Design changes mid-project: Every revision after permitting restarts part of the review.

Final inspections are one of the last steps before project completion. Once they pass, you can expect the remaining paperwork and closeout process to wrap up within a few weeks. 

Set Realistic Expectations From Day One

Understanding how long it takes to build an ADU means accepting that different stages have their own timelines. At Builders Innovation Group, we handle every stage from design through construction, giving you one team from start to finish. We’re also happy to discuss essential home addition considerations if you’re still weighing your options.

Call us today at (951) 528-1200 to start your ADU in Murrieta, CA.