ADU Setback Requirements: How Close to the Property Line?

Setbacks are the minimum distance your ADU must be from the property line. They directly affect whether a given lot has room for an ADU at all — especially on smaller infill lots.

California: 4-foot maximum setback

California Government Code 65852.2 caps rear and side setbacks at 4 feet for ADUs that meet state law standards. No city can require more than a 4-foot setback from the rear or side, though a larger street-facing setback may still apply. This is one of the most important ADU preemptions in the country.

Other states and typical setback rules

• Washington: no more than 5 feet from rear or side (HB 1337).
• Oregon: no more than 4 feet for lots subject to the state mandate.
• Texas, Florida, other states: no statewide preemption — setbacks are whatever the local code says, often 5–10 feet.

How setbacks affect lot coverage

Even if your jurisdiction allows a 4-foot setback, lot coverage limits (the maximum percentage of a lot that can be covered by structures) may independently constrain the ADU footprint. Check both the setback rule and the lot-coverage limit for your parcel.

Setback rules vary by parcel, zoning district and whether your lot is in a fire hazard severity zone. Always verify with your local planning department.