Building permits, zoning and land rules in Karnes County, Texas

Karnes County's Permitting Department lists development-determination, OSSF septic, floodplain and road-and-bridge work, but it does not list a general residential building permit for unincorporated land¹. Texas residential standards under Chapter 233, Subchapter F apply only when an eligible county adopts the required resolution or order, and that law does not require county approval before construction begins². We could not confirm that Karnes County adopted the required order, so ask the Permitting Department whether project-specific standards, notices or inspections apply before construction^2,3. If Subchapter F applies, a new house on a vacant lot needs inspections at the foundation, framing-and-systems and completion stages, arranged by the builder with a qualified inspector³. A platted subdivision can separately trigger county rules for minimum lot size, mapped flood hazards and driveway access⁸. An owner-builder should not treat state law as a blanket exemption from underlying requirements¹⁰.

Karnes County does not identify a general residential building-permit office for unincorporated land, so ask the county Permitting Department whether a building permit, construction notice or inspection applies to the project^1,2,3. The county Permitting Department also handles Road & Bridge permits¹. Reach the department at 830-780-3511 or visit 210 W Calvert Ave. Suite 155, Karnes City, TX 78118¹. Office hours are 8:00 am to 5:00 pm Monday through Friday, with a closure from 12:00 to 1:00¹. For a septic permit, submit a Determination Development Permit Application before the OSSF application; development applications use the county permit portal¹.

For subdivisions outside incorporated towns or cities, Karnes County lists a plat application fee of $100 per lot without roads or $3,000 plus $100 per lot with roads, with a $500 minimum for every new subdivision⁸. Amending a plat costs $200; revising a plat costs $100 per lot created plus publication costs⁸. Filing a final approved plat with the Karnes County Clerk costs $111 for the first page and $100 for each additional page⁸. These are subdivision fees, not a complete building-permit or septic-permit fee schedule, and the Commissioners Court may change them; ask the Permitting Department to confirm current charges before applying^1,8.

Karnes County has no county zoning in unincorporated areas¹. Municipal zoning is different: Karnes City expressly has no zoning ordinance regulating residential or commercial land use within its city limits, while Kenedy requires uses and structures to conform to its zoning districts^4,5. The countywide municipal picture is incomplete, so ask the relevant city about zoning approval before relying on the unincorporated-area rule⁴. Wherever the parcel lies, Karnes County remains the OSSF septic-permit authority¹. In county-governed subdivisions, standard spacing requires 1 acre for public water with conventional septic or a private well with public sewer, and 2 acres for a private well with conventional septic; dense spacing can allow smaller lots⁸. County subdivision requirements are separate from zoning: the rules specify setbacks of 25 feet from the county right-of-way and 15 feet at the sides and rear¹¹.

An OSSF (on-site sewage facility) built, altered, extended or repaired in Karnes County generally needs a permit, and the Permitting Department requires a Determination Development Permit Application before the OSSF application^1,7. Obtain authorization before construction, and have the owner or installer arrange the required inspection before installation is complete; the authorization expires after one year if no final inspection occurs^1,12. Texas has a narrow 10-acre exemption, but only when every condition—including the site evaluation, single dwelling and 100-foot property-line separation—is met⁷. An OSSF may receive only domestic sewage, not industrial or hazardous waste¹³. Aerobic systems require a maintenance contract for the first two years; afterward, a single-family owner must obtain another contract within 30 days or maintain the system personally, while commercial systems need continuous coverage¹². When a maintenance contract is required, the provider generally inspects and reports at least every four months, with limited electronic-monitoring exceptions¹⁴. Only 15.2% of Karnes County soils are rated "not limited" for a conventional drain field; other soils may need an engineered system, so arrange a site evaluation early¹⁵.

Unincorporated Karnes County has no county zoning rule limiting RV, tiny-home or manufactured-home occupancy or setting a minimum dwelling size⁶. An RV or tiny home still needs a lawful sewage solution, and constructing, altering, extending or repairing an OSSF generally requires a septic permit⁷. Karnes County handles OSSF septic permits countywide, including inside cities¹. Subdivision setbacks and private deed restrictions can affect placement or use even without county zoning¹¹. We could not confirm a county certificate-of-occupancy rule, so ask the Permitting Department before moving onto the property¹.

1. Confirm whether the parcel is inside a city, a municipal extraterritorial jurisdiction or a platted subdivision, because subdivision approval and zoning rules depend on location^4,11.
2. For unincorporated land, ask the Karnes County Permitting Department whether a residential building permit, construction notice, inspection or floodplain approval applies; no general home-building permit is listed, and adoption of the state residential-standards order was not confirmed^1,2,3.
3. If the parcel is inside a city, ask that city about its building permit and zoning approval; Karnes City has no zoning ordinance, while Kenedy administers its own zoning districts^4,5.
4. For every address in Karnes County, start the septic-permit process with the county: order the site evaluation, file the Determination Development Permit Application and then the OSSF application unless every condition of a state exemption is met^1,7.
5. Arrange the OSSF inspection before installation is complete¹².
6. Have a new well reviewed by the Evergreen Underground Water Conservation District before drilling⁹.
7. Obtain the applicable county-road or state-highway driveway permit^1,8,16.

Karnes County averages 31 inches of annual precipitation, with severe drought in 23.5% of years; have the Evergreen Underground Water Conservation District review a planned well before drilling^9,15. Check mapped flood hazards before buying subdivision land: Karnes County requires flood-hazard areas on plats and additional studies where base flood elevations are missing⁸. For a recently divided tract, confirm county plat approval or a qualifying exemption; agricultural use alone does not satisfy every exemption condition^8,11. The effective property-tax rate is about 1%, with a median annual bill near $1,344 and a typical home value around $220,444¹⁵.