Shed pads are usually reinforced slabs over compacted base; workshops and garages need thicker slabs and footings; additions need a designed foundation that suits expansive clay or rock, typically with drawings, a permit and inspections. In the City of San Antonio, sheds up to 300 square feet meeting setbacks are on the No Permit Required list. Contact Texas 811 before digging.
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Storage sheds, workshops, detached garages, carports, hot tubs and room additions all need a solid base. For small structures that's usually a simple slab. For anything attached to the house or built as living space, it means a designed foundation that has to meet the building code, and around San Antonio it has to be designed for the soil.
Common projects
- Pads for storage sheds, playhouses and garden buildings
- Slabs for workshops, detached garages and carports
- Pads for hot tubs, generators and AC condensers
- Foundations for room additions, enclosed patios and casitas
Sheds and small buildings
A shed pad is usually a reinforced slab over a compacted base, often with a thickened perimeter. In the City of San Antonio, the "No Permit Required" list includes one-story detached storage sheds, playhouses and similar buildings with a floor area of 300 square feet or less, as long as they meet setback rules. Larger detached accessory buildings need a permit and, under the city's contractor rules, a registered residential building contractor. Properties in historic or conservation districts can have extra design rules. Suburban cities, HOAs and county rules differ, so check before you pour.
Workshops and garages
A slab for vehicles, tools or equipment generally needs more thickness and reinforcement than a shed pad, plus thickened edges or footings to carry the walls. If you'll cool or finish the space, ask about a vapor retarder and where plumbing and electrical conduit go before the pour.
Additions and soil
Most San Antonio homes sit on slab-on-grade foundations, and many are post-tensioned or stiffened with grade beams because of expansive clay. A new addition has to be designed to work with the existing house, not just poured next to it. That usually means engineered drawings, a permit and inspections before concrete is placed. Many builders also get a geotechnical report on clay sites so the design reflects how much the soil can swell. On Hill Country lots, the issue may be rock: footings can bear on limestone, but excavation may need rock saws or breakers.
Licensing in Texas
Texas doesn't issue a statewide license for concrete or general contractors. Local rules fill the gap. The City of San Antonio requires registration, insurance and a background check for residential building contractors, who handle additions, structural work, foundation repair and detached accessory buildings over 300 square feet. Other cities have their own registration rules. Ask your contractor which apply and who pulls the permit.
Site factors
- Drainage: keep the slab above surrounding grade and slope the ground away.
- Aquifer zones: lots over the Edwards Aquifer recharge zone in north Bexar and Comal counties can have impervious cover limits and other TCEQ or local rules.
- Septic fields: common on larger lots outside city sewer; keep slabs off them.
- Utilities: Texas law requires a Texas 811 locate request before digging.
Questions to ask
- Does this need a permit, and who will pull it?
- Are you registered with the city for this kind of work?
- Is there an engineer's design, and is a soils report recommended?
- What thickness, reinforcement and base are included?
Planning a building or addition? Request a slab or foundation contractor and include the structure's size and use.
See how it works
Frequently asked questions
Do I need a permit for a shed slab in San Antonio?
In the City of San Antonio, one-story detached storage sheds and similar buildings of 300 square feet or less that meet setbacks are on the No Permit Required list. Larger ones need a permit. Other cities and HOAs set their own rules.
Does Texas license concrete contractors?
Texas doesn't issue a statewide license for concrete or general contractors. Cities fill in: San Antonio registers home improvement, residential building, and sidewalk, curb and gutter contractors. Always ask for proof of insurance.
Do I need a soils report for an addition?
It isn't always required, but on expansive clay many engineers and builders recommend one so the foundation design reflects how much the soil can move. Ask your designer.
Sources and further reading
- City of San Antonio Development Services: No Permit Required list
- City of San Antonio Development Services: Residential permits
- City of San Antonio: Sidewalk-Curb permit application
- City of San Antonio: Building and home improvement contractor registration
- City of San Antonio: Sidewalk, curb and gutter contractor license
- Bexar County Public Works: Right-of-way permits
- City of Alamo Heights
- San Antonio Water System (SAWS)
- TCEQ Edwards Aquifer Protection Program
- Texas Water Development Board: Houston Black, the Texas state soil
- USDA NRCS Web Soil Survey
- Texas 811
- Texas A&M Forest Service: Texas Oak Wilt
- American Concrete Institute (ACI)
- Portland Cement Association (PCA)