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

Texas gives most counties no authority to require a general building permit: only a county over 250,000 people (or adjacent to one) may adopt a fire-code permit for certain commercial and multifamily buildings, and county residential building-code standards apply only where a county opts in near an international border⁴. Mason County has about 3,931 residents, and its official Sanitation & Floodplain page lists only OSSF (septic) and floodplain permits for unincorporated land, with no separate building-permit process^1,7. Treat that as a strong signal rather than a written guarantee: Mason County's own site does not carry a sentence stating outright that no building permit is required, so call the Sanitation & Floodplain office to confirm before you build¹.

Mason County's Sanitation & Floodplain Department, through its OSSF Designated Officer, administers septic permits for Mason County¹. Reach the office at (325) 347-2477, by email at mcdrossf@co.mason.tx.us, or at 201 Ft. McKavett St., Mason, TX 76856 at the county courthouse¹. The same department administers the floodplain-development-permit program, required before construction or a substantial improvement in a mapped flood hazard area^1,3. Land inside the City of Mason answers to a different office: the city's own Building Permits / Inspection Department enforces zoning and adopted International Building Codes within city limits, under city ordinances 10-312 and 13-322^8,9.

Unincorporated Mason County has no county zoning ordinance: Texas law gives counties zoning power only in a handful of specific situations, and Mason County is not one of them⁵. Because the county has no zoning authority over unincorporated land, it sets no minimum lot size, no setbacks, no lot-coverage limit, no building-height limit and no zoning districts, and RVs, tiny homes and manufactured homes are unrestricted by county zoning outside city limits². That is a real answer, not a research gap: it follows directly from Texas law giving a county like Mason no general zoning power². Inside the City of Mason, the opposite is true: city ordinance divides Mason into nine zoning districts, including a dedicated mobile-home-park district, so a parcel inside city limits is zoned even though the surrounding county is not⁹.

Zoning is not the only land-use rule outside the city: Mason County has subdivision regulations for land outside incorporated cities, so unless an exemption applies, subdivided land cannot be sold until the Commissioners Court approves the application and a plat is filed with the Mason County Clerk¹⁰. A division of a tract that was never platted, used primarily for agriculture, ranching, wildlife management or timber, and meeting the minimum frontage rules can be exempt, but the exemption ends if the land stops being used that way¹⁰.

Every new on-site sewage facility (OSSF) in Mason County needs a permit, regardless of the size or number of acres in the property¹. The county's OSSF Designated Officer administers the local program, reviews the application and issues an Authorization to Construct, valid for one year, before work can begin^1,3. Installation must be inspected before the system is covered; the authorized agent's inspection checks compliance with TCEQ criteria or the approved local order, whichever is stricter^3,11. Fees are $210 for a single-family residential system and $410 for any other system type, plus a re-inspection fee equal to half the permit fee, payable by check or money order only³. Texas has a narrow statewide permit exemption for a qualifying single-family OSSF on at least 10 acres, but Mason County's rule requires all new systems to be permitted regardless of acreage^1,12. With only 4.2% of the county's soils free of severe limits for a conventional septic drain field, expect many sites to need an engineered or alternative system⁷.

A homeowner may install their own system for a single-family home they own on land they own, with no part of the property developed for sale or lease, but the county permit is still required and construction must not start before approval^3,12. Call the county's designated representative at least 5 working days ahead of the inspection that must happen before the system is covered³.

Yes, with conditions: unincorporated Mason County has no zoning ordinance, so it sets no rule restricting RV, tiny-home or manufactured-home occupancy on private land, a direct result of Texas law giving the county no general zoning power². The same lack of zoning means there is no minimum dwelling size and no accessory-dwelling rule in unincorporated Mason County². Two things still apply everywhere in the county: any wastewater system connected to the RV, tiny home or manufactured home still needs an OSSF permit from the Sanitation & Floodplain office, and a site inside a mapped flood hazard area still needs a floodplain permit first^1,3. Inside the City of Mason, the opposite is true: city zoning includes a dedicated mobile-home-park district, so manufactured-home placement is restricted to zoned areas within city limits⁹.

1. Confirm the parcel is outside the City of Mason's limits; the county has no zoning while the city does, so the rules differ sharply on either side of the line^5,9.
2. Call the Sanitation & Floodplain office at (325) 347-2477 before you design a wastewater system: every new OSSF needs a county permit, whatever the acreage¹.
3. Budget $210 for a single-family OSSF permit, or $410 for any other system type, payable by check or money order³.
4. Get your Authorization to Construct before work starts, and schedule the required installation inspection with the Sanitation & Floodplain office in advance³.
5. Ask the Sanitation & Floodplain office whether the parcel sits in a mapped flood hazard area; if it does, a floodplain development permit, valid for one year, is required before construction³.
6. If your driveway will connect to a state highway, file TxDOT Form 1058 and wait for a fully executed permit before you build it⁶.
7. No county building permit or inspection has been confirmed as required, but call the Sanitation & Floodplain office to double check before you start, since the county's own pages do not say so in writing¹.

Soils are a real constraint here: only 4.2% of Mason County has soils without severe limits for a conventional septic drain field, so plan on an engineered or alternative OSSF system on most parcels⁷. The county sees severe drought in roughly 31.4% of years, a dry stretch worth planning for with both a private well and any pond or tank⁷. Land is gentle -- 91.3% sits at 15% slope or less -- and about a quarter of the county, 25.6%, is wooded⁷. Mason County is rural and low-density, with 3,931 residents at about 4.2 people per square mile, roughly 90 miles from the nearest metro area⁷. A driveway onto a state highway needs a TxDOT permit before construction, not just a county sign-off⁶. Property taxes run an effective 0.8% rate, with a median annual bill of $2,239⁷.