Detached garages and RV garages in the Austin area, from a city lot to acreage

Almost always, because the exemption is small. Austin's work-exempt list clears a residential detached accessory structure only at one story, no more than 200 square feet of floor area and no more than 15 feet high, creating no dwelling, with no plumbing, outside a flood hazard area. The list names no detached garage, workshop or carport, and exempt work still has to comply with the building codes.

So it goes to the Residential Plan Review Division, which reviews additional buildings on a house lot under the 2024 International Residential Code and Chapter 25-12 local amendments. From July 1, 2026 the target for new construction and additions is 10 business days, and the FY 2025-26 residential plan review fee starts at an $896.50 base for new construction up to 1,000 square feet plus a $106.72 application processing fee. No row on the city's timeline page is written for a detached garage, workshop or carport.

Inside any other city limit, that city runs the permit. Williamson County's own frequently asked questions say to check with the city if the property is in a city or its extraterritorial jurisdiction, and that cities in their extraterritorial jurisdiction, emergency services districts, TCEQ and the health district may require permits.

SourcesCity of Austin Development Services, work exempt from building permits, read 2026-09-20; City of Austin Development Services, residential plan review, and the residential building plan review and inspection permit fees (FY 2025-26), read 2026-09-20; The source was read and does not list this.Williamson County, frequently asked questions, infrastructure and developers, read 2026-09-20.

Six counties, six answers, and none of them borrows another's. Below is what each county's own page lists for a detached accessory building outside the city limits.

Read the Williamson row for what it is. None of the County Engineer, frequently asked questions, floodplain, Road and Bridge or Development Services pages read lists a building permit, a building code or a plan review for an accessory structure. That is a county site not listing one, not a statement that nothing applies.

Caldwell is the other slow read: its ordinance excludes residential garages, sheds and barns from commercial site construction, then does not say whether one on a residential lot needs a county permit.

Travis County carries its full record, and the order a build runs in is on building a metal building in the Austin area.

SourcesTravis County TNR Development Services, Commercial Site Plan, read 2026-09-20; The source was read and does not list this.Williamson County, frequently asked questions, infrastructure and developers, read 2026-09-20; Bastrop County Development Services, and the Development Services application fees, read 2026-09-20; Caldwell County Development Ordinance, revised February 14, 2023, and the subdivision and development fee schedule, read 2026-09-20; Lee County Development Services Department, read 2026-09-20; Burnet County, on-site sewage facilities and development permits, read 2026-09-20.

Usually not, because the statute names the building. Occupations Code 1001.056 exempts from engineering licensing a private dwelling, a garage or other structure pertinent to one, and a private building used exclusively for farm, ranch or agricultural purposes.

Where the building is not pertinent to a dwelling, the size test takes over: one story, a total floor area of not more than 5,000 square feet, and no clear span between supports greater than 24 feet on the narrow side, provided no engineering services are offered to the public. Past 24 feet of unsupported span, only the roof supporting members, the trusses and beams, have to be engineered or pre-engineered.

Design against that 24-foot number early, because two RV bays abreast crosses it. Where an office asks for sealed sheets anyway, a Texas professional engineer seals them: in unincorporated Travis County the accessory building on a residential lot files the Development (Residential) permit, while the non-residential permit is the one carrying a site plan sealed by a Texas-licensed engineer.

SourcesTexas Legislature Online, Occupations Code Chapter 1001, engineers, read 2026-09-20; Travis County TNR Development Services, Commercial Site Plan, read 2026-09-20.

Start with the rig, not the building. Measure the height over the roof air conditioner, the ladder and the antenna, the length with the bumper racks on, the width with the mirrors out. The door opening comes from those numbers plus room for the track and the opener, the eave height comes from the door, and the frame comes from the eave.

The slab gets poured once. Thickness, reinforcement, the apron the RV turns on and the fall that moves water away from the door instead of under it are all on the concrete slab and foundation guide.

An independent local metal building contractor who works your county builds it and prices it after walking the lot. Bring the measured rig, the bay count, whether you want it conditioned, and the address, because the address decides the paperwork above.

Both can, and both sit apart from any building permit. In unincorporated Travis County, Travis County Code Chapter 464 requires a development permit before any construction or development: an A permit is the basic one, a B permit is the Special Flood Hazard Area permit, and both go through the Floodplain Administrator with scaled plans showing the structures, the floodplain location and lowest floor elevations. A violation is a Class C misdemeanor with a fine of up to $500 per day.

In Williamson County, where a property is within or adjacent to a 100-year floodplain, structures have to be elevated at least one foot above base flood elevation and a Floodplain Development Permit has to be issued by the County Engineer's Office before construction. The $75 application fee does not itself authorize construction, a signed and sealed FEMA elevation certificate is required after the slab and again at completion, and the permit expires one year from issue.

The driveway is the other one, and a coach makes it wider. A new driveway on a state highway, or a change to an existing one, takes Form 1058 filed with the local TxDOT district office, and the state right of way is off limits to work until that permit is executed and the district has had 24 hours of notice. The county road version is on TxDOT and county driveway access.

SourcesTexas Department of Transportation, Access Management Manual, chapter 2 section 4, permits, and the Use of Right of Way by Others Manual, access driveways, read 2026-09-20; Travis County TNR, floodplain maps, and Travis County Code Chapter 464, read 2026-09-20; Williamson County, floodplain management, and the Flood Damage Prevention Order, read 2026-09-20.

A detached garage on a house lot is an accessory structure of a single-family dwelling, and the statute files those under the residential energy code. Health and Safety Code 388.003(a) adopts the energy efficiency chapter of the International Residential Code as it existed on May 1, 2015 as the state energy code for single-family residential construction from September 1, 2016, and section 388.002(12) defines single-family residential as a detached one- or two-family dwelling or a multiple single-family dwelling of not more than three stories, including its accessory structures.

That record sets no separate rule for an unconditioned garage, so this page states none. If the plan is insulation, a mini split or a bathroom out there, ask the office that permits your building which parts of that chapter it enforces.

SourceTexas Legislature Online, Health and Safety Code Chapter 388, Texas building energy performance standards, read 2026-09-20.