Building a barndominium or barn in Kerr County: permitting and site work

Kerr County does not run a general building code or building inspections in the unincorporated county. The binding county-level items are the septic (OSSF) permit, plus subdivision platting, floodplain, and driveway and access rules where they apply. Inside the City of Kerrville, city building permits apply. If your land is outside the city, expect the septic authorization, not a building inspector, to be your gate.

The on-site sewage facility permit, the septic permit, is usually the binding approval for a rural Hill Country build. In Kerr County it runs through the Kerr County Environmental Health Department. Located on Earl Garrett Street in Kerrville. You will need an Authorization to Construct before the septic system goes in. Confirm the current phone, email, and forms on the county Environmental Health page.

Local detail: Kerr County Environmental Health is the local OSSF authority (a TCEQ Authorized Agent). Worth knowing: the Upper Guadalupe River Authority used to run the septic program here under contract, but Kerr County created its own Environmental Health Department and took the program over in 2003. So permits come from the county now, not UGRA. You must get the Authorization to Construct in hand before you install the system.

Visit the official Kerr County page to confirm current forms, fees, and contacts.

The 10-acre exemption no longer covers a new build in Kerr County. The Commissioners' Court approved a new county OSSF Order on July 13, 2026, and since it took effect on August 7, 2026 the county requires a permit for ALL new septic systems regardless of tract size, using the authority 30 TAC 285.10 gives a county to set more stringent standards. Plan on a permitted system and an Authorization to Construct for any new home or any upgrade to an existing one. The county states the change is not retroactive: an existing system stays grandfathered as long as it keeps meeting the original state exception, meaning it serves one single-family dwelling on a tract of 10 acres or more, all sewage is disposed of on that property, and it is not causing a nuisance or polluting groundwater. Add a second dwelling or another structure served by the system and that protection ends. Whatever the permit status, on the thin limestone soils around Kerrville the design usually lands on an aerobic treatment unit rather than a conventional trench. Confirm the current order with Kerr County Environmental Health before you plan around any of it.

Kerr County is not in TCEQ's regulated Edwards Aquifer Protection Program, so a building project here does not trigger a Water Pollution Abatement Plan. The county sits in the upper Guadalupe River basin. Groundwater protection still matters for septic design, but the formal Edwards recharge-zone review that applies in the San Antonio and Austin counties does not apply in Kerr.

The Hill Country sits in the roughly 105 to 115 mph design wind speed band (3-second gust, Risk Category II) under ASCE 7-16, the standard most Texas building codes reference. Most parcels fall between mapped contours, so a designer pulls the exact value for your address from the ASCE Hazard Tool. The local twist is the topographic factor, Kzt: an exposed ridge, hilltop, or escarpment raises the effective wind pressure on a building, sometimes by half again versus flat open ground. A metal or post-frame building on a Hill Country ridge should be engineered for that, which is one reason a sealed design from the builder matters here.

The Upper Guadalupe River Authority manages river and watershed issues in the county, and groundwater is regulated through the applicable conservation district. If your build depends on a well, budget for a limestone drill and confirm district registration before you finalize the site plan.

A 1-d-1 open-space valuation from the Kerr Central Appraisal District lowers the tax valuation on qualifying land. It applies to land only: barns, shops, silos, and a barndominium are appraised separately at market value. There is no county square-footage rule that makes a building permit-free, and an ag valuation does not remove the septic permit. If a structure directly supports a qualifying ag use, ask the appraisal district how it is handled rather than assuming.