Building permits, zoning and septic rules in Montgomery County, Texas

Yes. Every residential structure or addition in unincorporated Montgomery County needs its own county development permit; rental homes, apartments, RV parks, model homes and business structures follow the commercial route¹. The residential structure fee is $150 outside the 100-year floodplain and $200 inside it, and county permitting fees are non-refundable¹. A development permit expires 180 days after entry into the permitting system, regardless of whether review is pending, approved or denied¹. Montgomery County has adopted only selected International Building Code provisions for buildings covered by its Fire Code; one- and two-family dwellings and multifamily buildings with three or fewer units are outside that Fire Code scope⁴. Buildings subject to Montgomery County’s Fire Code need Fire Marshal inspections and a Certificate of Compliance before occupancy⁴. Cleveland, mainly in Liberty County but extending into Montgomery County, issues city building permits; Tomball, mainly in Harris County but extending into Montgomery County, requires a city permit to build or enlarge an RV park^11,12. Septic permits remain a separate Montgomery County Environmental Health responsibility⁵.

The Montgomery County Permit Department handles residential development permits at 501 North Thompson, Suite 100, Conroe, Texas 77301; call 936-539-7836¹³. Rental homes, RV parks, apartments and structures used for business are commercial applications rather than ordinary homeowner applications¹. Montgomery County Environmental Health Services administers OSSF permits as the county's local agent for TCEQ; its office is at 501 N Thompson Street, Suite 101, Conroe, Texas 77301, and its phone is 936-539-7839^5,14. Montgomery County Floodplain Administration handles floodplain determinations and development requirements from Suite 100 at the same North Thompson address; call 936-539-7836¹⁵. Ask the Permit Department whether an owner-builder development-permit exemption applies, because the available county materials do not confirm one; Texas trade-license exemptions for work on an owner's residence or homestead do not themselves erase the county development permit⁸.

Montgomery County does not administer county land-use zoning; the county rules here concern unincorporated land, while municipal zoning varies². Cleveland, a city mainly in Liberty County that reaches into Montgomery County, administers its own zoning inside city limits¹⁶. County Environmental Health handles septic permits separately from municipal zoning⁵. No county zoning does not remove the development-permit requirement for structures or additions¹. For unincorporated Montgomery County applications, a utility-district service letter documents district water or sewer service, and property without public sewer needs a septic permit¹.

Montgomery County Environmental Health Services issues and approves septic permits as the local TCEQ agent⁵. A new system application requires a site evaluation and soil analysis, an OSSF design by a registered sanitarian or professional engineer, floor plans, floodplain information, the application fee and a $10 TCEQ assessment fee⁵. For new systems and add-on modifications, request the county inspection by 3:00 p.m. two business days before it is needed; do not backfill or use the system until the county approves it and issues a Notice of Approval⁵. Only about 2.2% of Montgomery County soils are rated without severe limits for a conventional drain field, so establish system feasibility and cost before buying¹⁷. A narrow state permit exemption can apply to one home on at least 10 acres only when all conditions are met, including a licensed site evaluation and keeping every OSSF component at least 100 feet from the property line⁷. Montgomery County does not permit a septic system in the regulatory floodway⁵.

Unincorporated Montgomery County has no county zoning rule restricting RV, tiny-home, manufactured-home or temporary-camping occupancy, or setting minimum dwelling size, lot size, setbacks, lot coverage or building height⁶. Montgomery County still requires a development permit for each structure or addition, and processes RV parks as commercial development¹. Land without public sewer must follow the county septic process unless all conditions of a state exemption apply^1,7. Ask Montgomery County Environmental Health Services about a composting toilet, privy or other alternative before relying on it as the parcel’s sewage solution¹⁴.

1. Confirm whether the parcel is unincorporated or under a municipality with its own zoning or documentation requirements².
2. Get the legal description, site plan or survey, new-development address verification, utility-district letter, and any applicable stormwater or culvert paperwork together¹.
3. Submit a separate development-permit application for every structure or addition and account for the 180-day expiration measured from system entry¹.
4. If public sewer is unavailable, complete the county septic design and permit process before construction^1,5.
5. Ask Floodplain Administration about a Class B development permit for land wholly or partly in a special flood hazard area; floodplain fill or excavation needs approval before work¹⁰.
6. Arrange the septic inspection before backfill or use, and obtain the county's Notice of Approval⁵.
7. For a state-highway driveway, obtain the TxDOT access permit; for county access, ask whether the parcel's precinct requires culvert verification^1,18.

Check wastewater feasibility before buying: only about 2.2% of Montgomery County soils are rated without severe limits for a conventional drain field, and a new system needs a site evaluation, soil analysis and professional OSSF design^5,17. New septic installation and repair or replacement are prohibited in the floodway⁹. Structures in the 100-year floodplain or within 100 feet of its boundary require elevation or acceptable flood openings and a final elevation certificate⁹. Floodplain fill or excavation also needs a development permit and generally an engineer’s certification; an affected area of 15,000 square feet or less may qualify for a certification exemption, but still needs the permit¹⁰. Ask the relevant precinct about culvert documentation; the residential application identifies Precinct 4 verification or an inspection receipt where applicable¹. We could not confirm a private-well permit rule; ask the Permit Department which water-service approvals your parcel needs¹³.