ADU Permits · 2026
ADU Setback Requirements in California (2026)
In 2026, California state law limits ADU setbacks to a maximum of 4 feet from your side and rear property lines for a new detached unit. If you are converting an existing structure (like a garage) within its current footprint, the required setback is zero. The front setback simply matches what your primary house already follows.
The short version: For a detached ADU, the most a city can require is 4 feet from your side and rear lot lines. Conversions within an existing footprint need no added setback at all. The front follows your main home. These numbers are set by state law and override stricter local rules, but the exact distances on your specific lot are confirmed during a feasibility study and the site visit.
What a setback actually is
A setback is the minimum distance your building has to sit from a property line. Cities use them to manage spacing, light, fire access, and neighbor privacy. For most of California’s history, ADU setbacks were large, often 5 to 15 feet, which made backyard units impossible on many lots.
That changed. State ADU law now caps how strict a city can be, and a city cannot require more than the state allows. This is the single biggest reason a backyard that “didn’t have room” a few years ago usually has room today.
The 2026 California setback rules at a glance
| Situation | Side setback | Rear setback | Front setback |
|---|---|---|---|
| New detached ADU | 4 ft max | 4 ft max | Matches primary residence |
| Conversion within an existing footprint | 0 ft | 0 ft | Existing footprint stands |
| Addition to an existing structure | 4 ft max on new walls | 4 ft max on new walls | Matches primary residence |
| ADU above a garage / second story | 4 ft max | 4 ft max | Matches primary residence |
A few important notes on this table:
- 4 feet is a ceiling, not a floor. A city may allow you to build closer in some cases, but it cannot force you farther than 4 feet on the side and rear for a new detached unit.
- Conversions are the big win. If a permitted structure already sits on a line, you can keep an ADU in that exact footprint with no new setback required. This is what makes a garage conversion to ADU so flexible.
- Front setbacks are not separately capped at 4 feet. Instead, the front follows whatever your primary home is already required to follow. In practice, ADUs almost always go in the back or side yard anyway, so the front rule rarely drives placement.
Why the 4-foot rule matters so much
Four feet does a lot of quiet work. It is enough room for a person to walk around the unit for maintenance, painting, and gutter cleaning. It keeps your ADU off the fence line so it does not crowd the neighbor. And it gives the factory-built home a clean drop zone for the crane.
Because the cap is only 4 feet, the buildable area on a typical Monterey County or Santa Cruz County lot is far larger than most homeowners assume. A yard that looks tight on paper often holds one of our larger homes once you measure from the actual 4-foot line instead of an old 10-foot one. If you are still deciding whether your lot qualifies at all, our guide to building an ADU on your property walks through the first checks.
Corner lots and the front-line question
Corner lots have two “street-facing” sides, and that trips people up. Here is the plain-English version: the side that runs along the street is usually treated with the same setback your primary home uses along that street, not the relaxed 4-foot rear-yard number. The interior side and the true rear still get the 4-foot cap.
This is exactly the kind of detail that varies by city and by how your parcel is mapped, so we never guess. On a corner lot, the real answer comes from pulling your parcel and confirming which lines are “front” in the city’s eyes. That happens in the feasibility study before you commit to anything.
How setbacks shape model placement
Setbacks decide three things at once: how big a footprint fits, which way the home faces, and where the crane sets it down. Because our homes are roughly 97% built in our Salinas factory and delivered by crane, we plan placement carefully so the unit clears the 4-foot lines and any utilities.
Our 14 models run from 405 to 1,200 square feet, in rectangle, L-shaped, and U-shaped layouts, which gives real flexibility when a lot is shaped oddly or pinched on one side.
| If your buildable space is… | Models that tend to fit well | All-inclusive total* |
|---|---|---|
| Tight or narrow (small side yard) | Four Fifty (450 sq ft), The 405 (405 sq ft) | $180,000 to $237,000 |
| Standard backyard | Six Sixty (660 sq ft), Five Five Five (555 sq ft) | $267,000 to $287,000 |
| Generous lot | Nine Forty-Five 3/2 (945 sq ft), Eight Eighty-Five 2/2 (885 sq ft) | $402,000 to $434,000 |
| Large lot, courtyard option | Twelve Hundred (1,200 sq ft), Twelve Hundred U (1,200 sq ft) | $507,000 to $557,000 |
*Includes a permitting budget, not final permit costs. Permits and property-specific site work (septic, retaining walls, etc.) vary by property and are confirmed in your feasibility study.
Every total above includes a permitting budget along with plans, the foundation, the factory build, delivery, utility hookups, appliances, and final inspection. Setbacks themselves don’t add a line item to your price, since staying inside the 4-foot cap is simply where the home sits. Exact permit costs are set by your city and county and get confirmed in your feasibility study, along with any property-specific site work your lot might need. To see all 14 side by side, visit our models page, and to estimate your own configuration, try the cost calculator.
L-shaped and U-shaped layouts on tricky lots
When a lot is wide but shallow, or has a setback eating into one corner, a rectangle is not always the best fit. That is why several of our larger homes are L-shaped, and our flagship Twelve Hundred U wraps around a private courtyard. These shapes let us tuck the home into the buildable envelope while still hitting full bedroom counts. The L and U layouts often unlock a yard that a single long rectangle could not.
Setbacks, parking, and the rest of the rules
Setbacks are one piece of placement. Parking is another, and the good news is that state law caps required ADU parking at one space, with broad exemptions (near transit, in a historic district, when replacing a garage, and more). We cover that fully in our guide to ADU parking requirements. For the complete picture of what 2026 state law allows, see our overview of California ADU laws.
Frequently asked questions
Can a city require more than a 4-foot setback for my ADU?
No. For a new detached ADU, state law caps the side and rear setback at 4 feet, and a city cannot require more than that. Some cities allow you to build closer in certain situations, but 4 feet is the legal ceiling they cannot exceed.
Do I need any setback at all for a garage conversion?
No added setback is required if you keep the ADU within the existing permitted footprint. If your garage already sits on or near a property line, an ADU can stay in that same footprint. Adding new walls outside the original footprint brings the 4-foot rule back into play for the new portion.
How do setbacks work on a corner lot?
The side that faces a street is usually held to your primary home’s street setback, while the interior side and rear get the 4-foot cap. Corner lots vary a lot by parcel and city mapping, so the precise lines are confirmed when we pull your parcel during the feasibility study.
What about the front of my property?
The ADU front setback matches whatever your primary residence is required to follow. Since ADUs almost always go in the back or side yard, the front rule rarely affects where the home actually lands.
Will setbacks limit which model I can build?
Sometimes, but less than you would think. Because the cap is only 4 feet, most yards fit more home than expected. If space is tight, smaller models like the Four Fifty or The 405 fit narrow envelopes, and L-shaped or U-shaped layouts help on oddly shaped lots. We confirm the exact fit at the site visit.
See exactly what fits your lot
The only way to know your real setback lines and which of our 14 models fits is to measure your specific parcel. Our team handles that for you in a feasibility study. We pull your property, confirm the setbacks, and show you what fits.
Start with a feasibility study and we will map your buildable space, confirm your setbacks, and walk you through the models that fit your backyard.