Liberty Hill

ADU Pass helps homeowners in Liberty Hill, Williamson County, Texas navigate the permit paperwork for building an accessory dwelling unit. This area covers 1 ZIP code.

1 ZIP code
Williamson County — county ADU rules and overlays

County regulatory overlays

Williamson County administers flood-hazard, and (where mapped) coastal, wildland-fire, historic, and airport overlays that shape ADU project feasibility. The most consistent overlay across the county is FEMA NFIP floodplain regulation; other overlays apply to specific geographies inside the county.

  • FEMA NFIP Special Flood Hazard Areas in Williamson County — A new ADU in a mapped SFHA must be elevated to or above the Base Flood Elevation; cost impact on the project is often material.
  • Coastal / hurricane wind exposure — Confirm design wind speed and exposure category at the building department.
  • Historic districts and individually-listed historic resources

County permitting (unincorporated parcels)

Williamson County regulates construction in unincorporated territory through its development services / building department, in cooperation with the county fire marshal and public works. Because Texas counties have no zoning authority (Tex. Loc. Gov't Code Ch. 232), unincorporated permitting addresses subdivision and plat compliance, residential building-code inspection, on-site sewage facility (OSSF) compliance under 30 TAC Ch. 285, floodplain compliance, and 911 addressing - it does not impose a use-based ADU restriction. A detached secondary dwelling on an unincorporated parcel is permitted as an ordinary residential structure through the county's residential-building permit pathway. Most ADU activity in Williamson County occurs inside incorporated cities, where city zoning controls apply.

DepartmentWilliamson County Development Services / Planning Department
Texas state — ADU law and programs

State ADU law

Texas has NOT enacted a statewide ADU preemption or ADU-by-right statute. Local governments (municipalities and counties) retain full authority over ADU zoning, setbacks, parking, size limits, owner-occupancy, and permitting. Two recent housing-reform bills in the 89th Legislature (2025) touch density and zoning procedure but do NOT preempt ADU-specific local rules: SB 15 (Bettencourt, signed 2025-06-20, effective 2025-09-01) caps minimum single-family lot sizes in cities over 150,000 in counties over 300,000, and HB 24 (signed 2025-06-20, effective 2025-09-01) raises the protest petition threshold for zoning changes. A dedicated ADU-preemption bill — SB 673 (Hughes, 2025) — passed the Texas Senate on 2025-04-10 and was reported favorably by the House Land & Resource Management Committee on 2025-05-08, but died on the General State Calendar when the 89th Regular Session adjourned on 2025-06-02. In the absence of a state ADU statute, homeowners must consult the ordinance of the municipality (or the county's subdivision rules for unincorporated areas) where the lot sits.

State financing programs

Texas does not operate an ADU-specific statewide loan, grant, or forgivable-loan program comparable to California's CalHFA ADU Grant. The Texas Department of Housing and Community Affairs (TDHCA) administers the state's general housing finance programs — My First Texas Home, My Choice Texas Home, Mortgage Credit Certificates, multifamily Housing Tax Credits, the Homeowner Assistance Fund, and Housing Trust Fund awards. None target ADU construction directly, but several can apply to an ADU as part of a primary-residence purchase or refinance when program criteria are met. ADU-specific financing in Texas is primarily local: the City of Austin's ADU Loan Program (administered through Neighborhood Housing and Community Development) and a handful of smaller pilot programs are the most visible, but these sit at the city tier, not the state tier.

Federal (United States) — ADU-relevant rules and programs

Federal ADU law

The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.

Federal financing programs

Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.

Federal tax credits

There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.

Federal housing programs

HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.

ZIP Code

  • 78642

Post Office

  • 2655 Ranch Road 1869, 78642