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

A new home in unincorporated Grimes County does not need a county building permit¹. The builder must still file the county's Notice of Construction and Notice of Inspection forms, but those notices require no county approval or fee¹. New residential construction beginning on or after December 18, 2024 must comply with the 2021 International Residential Code, although Grimes County does not inspect residential structures⁹. Grimes County otherwise does not regulate building codes outside that residential compliance reporting, while municipalities may administer their own codes². Separate county approvals still matter: all development requires a Development Permit and a Floodplain Development Permit, and septic or driveway work can trigger additional permits^5,7,9,10.

Grimes County does not operate a traditional residential building department that reviews plans and sends county inspectors; Development Services collects the required paperwork⁹. A Grimes County Development Permit application must be completed by the property owner or legal representative and may be sent to gcpermits@grimescountytexas.gov or delivered to 270 FM 149 W., Anderson, Texas 77830⁹. The residential Notice of Construction and Notice of Inspection forms go to that same email or address⁹. Contact Development Services at (936) 873-6465 about development paperwork and residential notices⁹. The Floodplain Administrator handles the separate Floodplain Development Permit, which only the property owner or legal representative may apply for and which is approved after the project's other permits are issued⁵. Development in the floodplain needs plans signed and sealed by a licensed Professional Engineer, under the Flood Damage Prevention Order approved January 21, 2026⁵.

Unincorporated Grimes County has no county zoning regulation or published county zoning districts². The county still regulates flood-hazard development, subdivision plats, driveways and culverts, and work in county rights of way². The lack of county zoning means the county sets no minimum dwelling size, minimum lot size, setbacks, lot-coverage limit or building-height limit in its unincorporated area⁸. It also leaves accessory dwellings, RV occupancy, tiny-home occupancy, manufactured-home occupancy and temporary camping unrestricted under county zoning rules⁸. City rules are different: Navasota has residential, commercial and industrial zones and processes for zoning changes, conditional uses, planned-unit developments and variances³. Confirm whether a parcel is inside a municipality or an area where municipal subdivision authority applies before relying on the county answer^2,7.

Grimes County Environmental Services permits and inspects on-site sewage facilities within the county⁴. A permit is generally required to construct, install, alter, extend or repair a septic system¹⁰. Only 3% of county soils lack severe limitations for a conventional drain field, so arrange the site evaluation before committing to a house location or system budget¹¹. A narrow exemption may apply to a single dwelling on at least 10 acres when a licensed site evaluator or engineer approves the site, every system component remains at least 100 feet from the property line, effluent stays on the tract and all other conditions are met¹⁰. On newly platted subdivision lots, pit privies and portable toilets are not acceptable waste-disposal systems; qualifying private systems must follow the applicable state on-site sewage rules¹². A proposed subdivision connecting to existing sewer must document the utility agreement and long-term treatment capacity¹².

Unincorporated Grimes County has no county zoning restriction on RV occupancy, tiny-home occupancy, manufactured-home occupancy or temporary camping, and county zoning sets no minimum dwelling or lot size⁸. Those answers do not remove the county's development, floodplain, septic or driveway requirements^5,7,9,10. The county requires its Floodplain Development Permit for all development in the unincorporated area, and all other permits must be issued first⁵. Grimes County's published materials do not confirm a general residential certificate-of-occupancy requirement, so ask Development Services what completion documentation and utility clearances apply to the particular RV or tiny-home setup. Inside a city, municipal zoning and building rules may change the answer².

1. Confirm jurisdiction and submit the Grimes County Development Permit application through Development Services⁹.

1. Arrange the septic site evaluation early, then obtain the OSSF permit from Environmental Services unless the tract meets every condition of the state exemption^4,10,11.

1. Before installing a county-road driveway or culvert, obtain the county permit and culvert sizing; a state-highway or farm-to-market-road connection needs TxDOT approval before county approval^7,13.

1. File the free Notice of Construction; it is not a building permit or county approval¹.

1. Obtain the $100 Floodplain Development Permit after every other permit has been issued^5,6.

1. Build to the 2021 International Residential Code, arrange the final inspection outside the county, and file the Notice of Inspection because Grimes County does not inspect the home⁹.

Start with septic feasibility: only 3% of Grimes County soils lack severe limitations for a conventional drain field¹¹. Confirm legal access as well as construction cost, because a new county-road driveway or culvert needs an approved permit and county-provided sizing before installation⁷. Check flood maps and ask the Floodplain Administrator what engineered plans or elevation documents the site requires, since floodplain development needs plans sealed by a licensed Professional Engineer⁵; the county's Floodplain Development Permit applies to all development in the unincorporated area and comes last⁵. For a recently divided tract, verify its plat and whether subdivision wastewater rules apply; platted lots cannot use pit privies or portable toilets as their waste-disposal system¹². A new well must be registered with the Bluebonnet Groundwater Conservation District before drilling, while non-exempt use also requires an operating permit¹⁴. Typical property tax is about 1.1%, with a median annual bill near $2,480¹¹.