Barndominium Builders in San Marcos, TX

Barndominium builders working around San Marcos are in one of the fastest-changing parts of Texas. San Marcos is the county seat of Hays County and reaches into Caldwell and Guadalupe counties. It is 30 miles southwest of Austin and 51 miles northeast of San Antonio, and the Census Bureau named it the fastest-growing city in the United States in 2013 and 2014.

Land on either side of the fault

San Marcos sits on the Balcones Fault, the boundary between the Hill Country and the coastal plains. The east side of the city is Blackland Prairie. The west side is rolling hills, forested or grassy. Hays County as a whole is mostly on the Edwards Plateau, with its southeast corner in the Blackland Prairies.

Hill Country side: expect slopes, limestone close to the surface and sites where driveway grades and runoff need planning.

Prairie side: expect flatter ground and expansive prairie clay. The USDA describes the region's signature Houston Black clay as having high shrink-swell potential and very slow permeability, which shapes slab and drainage design.

Springs and the aquifer

The San Marcos River rises from San Marcos Springs, which flow from the Edwards Aquifer into Spring Lake and are the third-largest collection of springs in Texas. The river has never run dry in recorded history. The Edwards Aquifer recharge zone follows the Balcones Fault, and TCEQ requires special permits for construction in recharge zones. If your land is in or near that zone, plan extra time for review of site work and septic.

Permits around San Marcos

Inside San Marcos, Kyle, Buda or another city, local permits and zoning apply. In a city's extraterritorial jurisdiction, Texas Local Government Code Section 233.153 says the city's building code controls. In unincorporated areas of counties covered by Chapter 233, Subchapter F, new single-family homes must meet the IRC as published May 1, 2008, or the county seat's version; the subchapter does not require prior county approval to start construction and does not authorize county zoning. Septic permits go through the authorized agent TCEQ lists for Hays County.

Weather notes

San Marcos averages 36.55 inches of precipitation a year and almost no snow. Its record high is 111 degrees and its record low is minus 2. A metal-skinned home needs to stay cool through long summers and avoid condensation during cold snaps, which is why insulation and air sealing come up early in our design conversations.

Growth and land

San Marcos went from 44,894 residents in 2010 to 67,553 in 2020, a 50.5 percent jump. Hays County grew 53.4 percent in the same decade, to 241,067 people and 93,534 housing units.

Shop space and living space

A lot of the appeal of a barndo in Hays County is room for a workshop, equipment or an RV under the same roof as the house. On hill lots, a long building may need to step with the grade or sit on a cut pad. On prairie lots, the main question is the slab: a wide shop bay and the living area should share one foundation design that accounts for clay movement.

What we look at on your lot

• Which side of the fault it is on, and what that means for soil and rock
• Whether it falls in the aquifer recharge or contributing zone
• Floodplain status near the San Marcos and Blanco rivers and local creeks
• City limits, ETJ or unincorporated county
• Deed restrictions or HOA covenants on metal buildings

Have land around San Marcos? Call (254) 401-5175 or

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to go over it with us.