Building Types | ADUs

ADUs in Texas 2026: No State Law, City by City

An accessory dwelling unit (ADU) is a smaller second home on the same lot as a house: a garage apartment, a backyard cottage or a unit inside the house. Texas has no statewide ADU law. The 2025 bill that would have created one, SB 673, stopped on the House calendar on May 26, 2025. So whether you can build an ADU, how large it can be, and whether you must live on the lot all depend on your city. This page compares the four largest cities and covers the loan, tax and rental rules that apply to an ADU anywhere in the state.

Four Cities Compared

Sources: Houston Sec. 42-1, Houston Sec. 26-492, Austin Ordinance No. 20231207-001, Austin parking ordinance, Dallas ADU page, Dallas parking reform, Dallas Board of Adjustment minutes, San Antonio UDC 35-371. FAR means floor area ratio: building floor area divided by lot area.

Why Texas Has No State ADU Rule

Cities hold zoning power in Texas, under Local Government Code chapter 211, so a statewide ADU rule would take an act of the Legislature. In 2025 Senator Hughes filed SB 673, "Relating to municipal and county regulation of accessory dwelling units; authorizing a fee." The Senate passed it. Its last action came on May 26, 2025, when it was placed on the House General State Calendar, and no later action is recorded.

The 2025 laws that did pass leave ADUs to the cities. VanPlex read SB 15 and SB 840 in full: SB 15 covers lot sizes on new single-family tracts, SB 840 covers housing on commercial land, and neither contains an ADU provision. SB 1567 (2025) limits occupancy caps in college towns. The other 2025 laws page lists every bill checked.

The Four Cities in Brief

Houston lets a lot hold a house and a detached second dwelling unit of up to 1,500 square feet and still count as single-family residential, as long as deed restrictions allow it; see the Houston page.

Austin replaced its accessory apartment rules with HOME Phase 1, which allows up to three units on SF-1, SF-2 and SF-3 lots and defines a tiny home as a unit of 400 square feet or less; see the Austin page.

Dallas allows one home per single-family lot, with a second only through an ADU overlay (an extra set of zoning rules for one neighborhood) or a Board of Adjustment special exception (permission for one property), and its citywide by-right ADU amendment was "Indefinitely Postponed on October 1, 2020"; see the Dallas page.

San Antonio allows one detached ADU per lot with the owner living on site, up to 1,600 square feet; see the San Antonio page.

VanPlex could not verify Fort Worth's ADU rules, because its code host blocked automated reading. The more Texas cities page lists what was verified for Fort Worth and El Paso.

Deed Restrictions Decide First

A private deed restriction can forbid an ADU that the city allows. Houston's Livable Places release says: "The new standards will not override active deed restrictions." Its FAQ adds that the City "has no authority to override or supersede active, private deed restrictions." Austin's HOME page tells applicants to check deed restrictions and restrictive covenants themselves. Read the recorded restrictions for your lot before you design an ADU. The zoning page explains how Texas courts enforce them.

Financing an ADU

Lender rules can limit an ADU plan even where the city allows it. Fannie Mae's Selling Guide B2-3-04 says: "Only one ADU is permitted on the parcel of the primary one-unit dwelling. ADUs are not permitted with a two- to four-unit dwelling." A house with one ADU fits that rule. A duplex with a backyard unit does not fit Fannie Mae's rules, so ask lenders which programs they offer for it.

Rent from an ADU can help you qualify, within limits. Under Fannie Mae's Selling Guide B3-3.8-02, a lender may count rental income from one existing ADU on a purchase or a limited cash-out refinance, but "the qualifying rental income amount from the ADU is limited to 30% of the total qualifying income." The financing page covers FHA and Fannie Mae rules for two to four units.

Paying for an ADU on Your Homestead

Article XVI, Section 50(a) of the Texas Constitution sets the rules for liens on a homestead. Under Section 50(a)(5), a lien for work and material used to build new improvements on a homestead is valid "if contracted for in writing." Building a new ADU is new construction, so put the contract with your builder in writing before work starts. Repairs or renovations of existing buildings need a written contract with the consent of both spouses, signed no earlier than the fifth day after the owner applies for the credit.

A home equity loan, borrowed against the value you already own, has its own limits under Section 50(a)(6): together with all other debt on the homestead it may not exceed 80 percent of the home's fair market value, it may not close before the 12th day after application, and it may close only at the office of the lender, an attorney or a title company.

Building and Permit Rules

Texas law defines a detached one-family or two-family dwelling as "residential" in Local Government Code 214.211, and the state minimum residential code for cities is the International Residential Code as it existed on May 1, 2012. Under those definitions, a detached ADU with one home is a one-family dwelling. Since January 1, 2009, Occupations Code 1301.551(i) has barred cities from requiring fire sprinklers in a one- or two-family dwelling. For energy, the state standard for one- and two-family homes of three stories or fewer is the energy chapter of the 2015 IRC, under the State Energy Conservation Office. Confirm with your city's building official how it classifies your ADU.

Permit deadlines apply too. Under Local Government Code 214.904, a city must grant or deny a permit application within 45 days or send written reasons why it cannot yet decide. If it misses its deadline, it may not collect the permit fees. In flood-prone areas, check the flood map first: Houston, for example, requires new residential construction in its 1 percent flood zones and its shaded X zone to have the lowest floor at least 2 feet above the 500-year flood elevation, as the insurance and flood page explains.

Property Tax on an ADU

Texas appraises property at its market value as of January 1 each year. If you live on the lot, your homestead's appraised value can rise by no more than 10 percent a year under Tax Code 23.23, plus the market value of new improvements. A new ADU is a new improvement, so its value is added outside the 10 percent limit in the year it first appears. Each appraisal district decides how to value the ADU and how much of the lot counts as your homestead, so ask yours before you build. The property tax page explains the $140,000 school homestead exemption and the rules for rental property.

Renting an ADU

A rented ADU makes you a landlord under Texas Property Code chapter 92. You must refund a security deposit within 30 days after the tenant leaves, under Section 92.103, and you may allow no more than three adults times the number of bedrooms, under Section 92.010. Some cities add their own limits: San Antonio's owner-occupancy rule bars the owner from receiving rent for the unit the owner lives in, and Austin limits short-term rental of one unit in a duplex or two-unit use to 30 days a year. The landlord rules page has the full list.

Where to Go Next

Related on VanPlex: the California ADU law page, for a state with a statewide ADU law, and Houston in the global multiplex zoning comparison.

Frequently Asked Questions

Official sources (checked October 2026)