Rental Cabins, A-Frames and Backyard Offices on Texas Land: What Needs a Permit

Picture a factory-built A-frame rolling down a ranch road on a flatbed. A weekend later, it's a rental cabin. Or a finished backyard office for someone who's done working from the kitchen table.

Small buildings are where a lot of people get their first taste of building something.

But nobody tells you about the permits until the truck is already on its way.

So here's what usually needs one in Texas. It comes down to two things: where the land sits, and what the unit actually is.

Where's the land?

Inside city limits, in a city's ETJ, or out in unincorporated county land. Cities can require building permits. Counties mostly can't, but they still control septic, floodplain and, in a lot of places, a general development permit.

Your county's GIS map or a quick call to the development office will tell you which one you're in.

County land: no building code (mostly)

Texas counties generally can't adopt building codes. The exception is Local Government Code 233.153. In counties that opt in, new single-family homes and duplexes have to follow the International Residential Code, with at least three inspections: foundation, framing and mechanical, and final.

That rule leaves out manufactured and modular homes. And a shed isn't a house. So for most cabins and offices, it probably doesn't apply.

Don't celebrate yet, though. Some counties want a development permit for nearly anything. Hays County's covers "any kind of development," outbuildings included.

Plumbing means septic

This is the one that gets people.

Under TCEQ rules, you need a permit and an approved plan to build, change or extend a septic system (an OSSF, if you want the acronym). It comes from your county's authorized agent, or the TCEQ regional office if there isn't one.

There's an exemption for one single-family home on 10 acres or more. But only if it's the only dwelling on the tract and the system stays 100 ft from property lines. Add a rental cabin and you've likely broken it.

Bastrop County, for example, says any structure used as a residence needs an OSSF permit, and it sizes guest houses and workshops at 180 gallons a day minimum.

The cabin is the easy part. The septic is what you're really buying.

Flood zones catch sheds too

If any part of the land is in a mapped flood hazard area, expect a floodplain permit before you set anything. Fort Bend County requires one before "any Development," meaning any man-made change: buildings, fill, grading, paving. Small accessory buildings (100 sq ft or less there) can't be lived in and need flood-resistant materials.

Even in a city, a shed that would normally skip a permit usually loses that pass in a flood zone.

So what is that thing, legally?

"Factory-built" doesn't mean one thing in Texas.

A HUD-code manufactured home is built on a permanent chassis to federal standards (at least 8 ft wide and 40 ft long, or 320 sq ft). TDHCA regulates it, and you get a Statement of Ownership instead of a title.

A modular home is built in modules and set on a permanent foundation. Look for a white decal with a blue star from TDLR. It becomes real property, like a site-built house. (I wrote more about the approvals side in my guide to factory-built homes in Texas.)

And the A-frame on a trailer with neither? Probably an RV, or not regulated as housing at all. That matters for your lender, your insurer and your county. Ask the seller, in writing, which label it has.

Inside a city or ETJ

Every city does it differently. Austin is a good example: a one-story detached accessory building skips a permit if it's 200 sq ft or less, 15 ft or less tall, has no plumbing, isn't a dwelling and isn't in a flood zone.

Add a bathroom or a bed and you're in permit territory.

Austin also requires a short-term rental license inside city limits. In its ETJ, you don't need one. Your city might be different, so call.

Renting it out?

Texas charges 6% state hotel tax on stays under 30 days. Booking platforms collect it if they've agreed to. If not, that's on you, and you register with the Comptroller. Cities, counties and special districts can add their own on top, generally up to 7%.

Read the deed restrictions

Lots of rural subdivisions have covenants on outbuildings, second homes or rentals, and Texas courts give HOAs a lot of room. One twist worth knowing: in 2022 the Texas Supreme Court said a covenant limiting land to "residential use" doesn't ban short-term rentals by itself, unless it sets a minimum stay.

Read the actual words.

Before you order

• City limits, ETJ or unincorporated county?
• Does the county require a development permit, and has it opted into the IRC rule?
• Is any part of the land in a FEMA flood zone?
• Will the cabin need a new or bigger septic system?
• Which label does the unit carry: HUD, modular decal, RV or none?
• What do the deed restrictions say about outbuildings and rentals?
• If you'll rent it: city rental license, Comptroller registration and local hotel tax.

Get the answers before the truck gets the directions.