Shed and equipment pads are usually reinforced slabs over a compacted base. Workshops, casitas and additions need thicker slabs and foundations designed for the soil, which on Austin-area expansive clay often means engineered designs. Texas has no state license for general or concrete contractors, so permits and inspections matter. Contact Texas811 before digging.
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Sheds, workshops, detached garages, carports, casitas, hot tubs and additions all need a solid base. For small structures that's usually a simple reinforced slab. For anything attached to the house or built as living space, it means an engineered foundation that has to meet the code your city has adopted and pass inspection. On Austin-area soils, the design matters a lot.
Common projects
- Pads for storage sheds, studios and garden buildings
- Slabs for workshops, detached garages and carports
- Pads for hot tubs, generators, pool equipment and HVAC units
- Foundations for room additions, casitas and screened porches
Small structures and pads
A shed or equipment pad is usually a reinforced slab over a compacted base, often with a thickened edge. Size it to the building plus a little extra, level it for the structure while letting water shed at the edges, and confirm setbacks from property lines, easements and, on septic properties, the drain field. Many cities require permits for accessory buildings above a certain size, and HOAs often set rules on size, location and appearance. Check before you pour.
Workshops, garages and casitas
Slabs for vehicles, heavy tools or living space need more thickness and reinforcement, plus thickened edges or grade beams to carry the walls. If you plan to cool or finish the space, ask about a vapor retarder under the slab and where plumbing and electrical conduit should go before the pour. Plumbing and electrical work in Texas is licensed by the state (the Texas State Board of Plumbing Examiners and TDLR), so those trades should be lined up early.
Foundations on expansive clay
East of I-35, the dark blackland clays can shrink and swell enough to damage structures, which is why many Central Texas homes are built on post-tensioned or heavily reinforced slab foundations designed for the soil. For an addition, expect your building department or builder to want a foundation designed for the site, sometimes with a soils report and an engineer's stamp. Tying a new addition to an older foundation needs careful detailing, since the two may move differently.
Building on rock
West of the Balcones Fault, limestone is often right under a thin layer of soil. That can mean firm bearing, but also excavation by rock saw or hammer, uneven rock that has to be leveled with base, and drainage that runs along the rock surface. Ask how the contractor will excavate and what that does to cost and schedule.
Permits, licensing and the aquifer
Texas has no statewide license for general contractors or concrete contractors, so the permit and inspection process is your main protection on structural work. Additions generally need a building permit, inspections before concrete is placed, and sometimes engineered drawings. In parts of Travis, Williamson and Hays counties over the Edwards Aquifer recharge or contributing zones, new impervious cover on a residential lot can trigger TCEQ requirements if it goes above the thresholds in the state's rules. Before any digging, Texas law requires contacting Texas811 to have utilities marked.
Questions to ask
- Does this need a permit, and who will pull it?
- Is the foundation engineered for my soil, and do I need a soils report?
- How thick is the slab, and what reinforcement and base are included?
- How will this tie in to my house or existing slab?
Planning a building or addition? Request a slab or foundation contractor and include the structure's size and use. For a garage floor coating later, see garage floors and epoxy.
See how it works
Frequently asked questions
Do concrete contractors need a license in Texas?
Texas doesn't have a statewide license for general contractors or concrete flatwork. Trades like plumbing and electrical are licensed by the state. Cities can have their own requirements, such as the City of Austin's Right-of-Way Contractor license for driveway and sidewalk work in the right-of-way.
Do I need a permit for a shed slab?
Many cities require a permit for accessory buildings above a certain size, and HOAs often have rules on size and placement. On lots over the Edwards Aquifer, added impervious cover can matter too. Check with your city before pouring.
Why are Central Texas foundations engineered?
The clays east of I-35 shrink and swell with moisture enough to damage structures, so foundations are commonly designed for the specific soil, often with post-tensioned or heavily reinforced slabs. Additions usually follow the same approach.
Sources and further reading
- American Concrete Institute (ACI)
- Portland Cement Association (PCA)
- Bureau of Economic Geology, UT Austin: Mount Bonnell and the Balcones Fault Zone
- City of Austin Transportation and Public Works: Right-of-Way Contractors
- City of Austin Development Services: Trees on Residential Property
- TCEQ: Edwards Aquifer rules for private residences
- City of Georgetown permits
- City of Leander: Driveway permit submittal packet
- City of Lakeway: Building applications and fees
- TxDOT Access Management Manual: Driveway permits
- Texas Department of Licensing and Regulation (TDLR)
- Texas811: Call before you dig