ADU rules in Lancaster County

A detached accessory dwelling unit is allowed only in the AG Agricultural district, only by special permit, and only on a lot of 20 acres or more (abutting section-line and half-section-line road right-of-way counts toward the area). One ADU per lot; a detached unit must sit within 200 feet of the main house and no closer to the street than the house. No other county district (AGR, R, B and the rest) lists an ADU, so acreage lots zoned AGR cannot add one under the county regulations.

The county definition covers a "subordinate building or portion of the main building," so an attached or internal unit (basement apartment, addition) goes through the same AG-only special permit with the same 20-acre minimum, size cap and owner-occupancy rule as a detached one. Outside AG there is no route for a second unit inside the house.

The ADU may not exceed the lesser of 1,000 square feet or 40 percent of the principal dwelling's square footage, with garages, carports and mechanical space excluded and unfinished basement space counted. The principal dwelling is measured as of the date the special permit is filed. The unit may have no more than two bedrooms and must meet the AG height limit (35 feet) while being no higher than the main house. The Planning Commission (or the County Board on appeal) may modify this condition when tied to health, safety and welfare.

The owner must live on the property, in either the main house or the ADU, and must record a deed restriction (to the County Attorney's satisfaction) with the Register of Deeds before any building permit is issued, stating the ADU cannot be sold separately. This is an ongoing requirement, and it is one of the two conditions (with the shared-access rule) that the Planning Commission and County Board may not waive. Nebraska has no statute limiting owner-occupancy rules.

The AG district's parking regulations require no spaces for dwellings (only places of religious assembly and schools have a parking minimum), and 13.050 adds no parking standard for the ADU. The ADU must instead share the main house's driveway access point to the road, a condition that cannot be waived. The Planning Commission may impose additional conditions on a particular permit.

An ADU needs a special permit, which requires a public hearing before the Lincoln-Lancaster County Planning Commission; the Commission's action may be appealed to the County Board. The Commission weighs neighborhood character, traffic, utilities and the Comprehensive Plan and may add conditions. The county fee for a special permit on more than 1 acre is $1,204 (Resolution R-26-0070, effective 10-1-2026). A building permit follows, after the deed restriction is recorded.

Because the owner must occupy either the main house or the ADU, one of the two units may be rented while the owner lives in the other. A recorded deed restriction bars selling the ADU separately from the main house. The county regulations contain no short-term rental, bed-and-breakfast or rental-licensing provision for dwellings; Nebraska's short-term rental statute (18-1758) binds only cities and villages, not counties.