ADU rules in Waco

Waco adopted a dedicated ADU ordinance in November 2023 (Ord. 2023-969). A detached ADU is a listed permitted use in every residential and office district (R-E, R-1A, R-1B, R-1C, R-2, R-3A through R-3E, O-1, O-2), but only on a legally platted single-family lot where a detached single-family primary dwelling exists or is built with the ADU; one ADU per lot. Detached units need a 10 ft rear setback, 5 ft side setback, and 10 ft separation from the primary dwelling; existing structures that are adapted or renovated are exempt from the setback standards.

The ADU definition expressly covers units attached to the primary dwelling, under the same permitted-use listing. An attached ADU must meet the regular setbacks of the zoning district rather than the reduced detached-ADU setbacks. All other Division 9 standards (one unit, one bedroom, size cap, design compatibility, shared utilities) apply equally to attached units.

The floor-area cap is unusual in being a whichever-is-greater test, so owners of larger homes can build above 500 sq ft (a 2,000 sq ft home allows a 600 sq ft ADU). Every ADU is limited to a single bedroom regardless of size. Converting an existing structure, like a garage, is exempt from both the size cap and the setback standards. Total lot coverage by buildings and paving cannot exceed 75 percent.

In single-family residence districts (R-E and R-1A/B/C), the property owner must sign a notarized affidavit, recorded with the McLennan County Clerk's Office, affirming the owner lives in either the main house or the ADU, and leasing both units at once is unlawful there. The code states no owner-occupancy requirement for ADUs in the R-2, R-3, O-1, or O-2 districts. Owner occupancy is defined by title records plus evidence like voter or vehicle registration.

A lot with an ADU needs three off-street spaces total. The ADU cannot take a separate new curb cut; its parking must use the same access as the main house unless the lot backs onto a public alley. No reduction or waiver provision appears in the ordinance.

Ord. 2023-969 added 'Accessory dwelling units' to the permitted-uses list (not the special-uses list) of all twelve base residential and office districts, so no special permit, public hearing, or Plan Commission approval is needed. The project still must meet the Division 9 design standards, connect to the primary dwelling's city water and wastewater service, and pass all other applicable city codes (building permit through Development Services) before occupancy.

A homeowner in a single-family district can live in one unit and rent out the other long term. Using the ADU as a short-stay rental means the STR facility license (life safety inspection, hotel occupancy taxes, occupancy caps of two adults per bedroom plus two per unit), and in the R-E and R-1 districts also a special permit through the Plan Commission and City Council taking roughly 60 to 90 days; the city's STR page gives an owner renting a backyard guest house as its example of Type I. Waco also enforces 500 ft spacing between licensed homestay or Type II rentals in the R-E through R-2 districts.