Concrete Foundation Contractor
in Houston, TX

Which concrete foundation is right for a Houston lot: slab, post-tension or pier and beam?

The soil report, the flood elevation and the budget decide it, in that order. A slab on grade with grade beams costs the least to build. Post-tension suits high-plasticity clay, and those foundations are designed to PTI DC10.5. A pier and beam, or a structural slab on void forms, carries the house on soil that does not move with the weather. Houston's engineers put that active zone at about 8 to 20 feet, so the piers reach below it. Then the flood rules weigh in. In the Harris County 100-year floodplain you cannot raise the pad with fill. The house goes on piers or vented foundation walls, and a licensed engineer has to design it. Inside city limits, Chapter 19 puts a new building in the 100- or 500-year floodplain two feet above the 500-year flood elevation. Read more on our pier and beam, post-tension slab and concrete slab pages. Send us the soil report and the flood elevation and we will tell you which one your lot wants.

Is it cheaper to build on a slab or on piers, and which one lasts longer?

A slab is cheaper to build and simpler to live with. A pier and beam costs more up front, gives you access under the floor for plumbing, and suits a flood-prone lot better. Houston's Foundation Performance Association lists the systems in order of rising risk and falling cost, and the engineer picks from that list for your lot. Neither one wears out on its own. A well-drained slab lasts the life of the house. Trees in or near the footprint cause most foundation repairs in this area, followed by plumbing leaks and uneven moisture around the edges. The piers under a pier and beam are drilled two ways here, belled or straight shaft, and the straight shafts usually go deeper. See drilled piers and foundation drilling for how we set them.

How much does a concrete foundation cost in Houston?

There is no flat rate, and a 2,000 square foot house or a 20x20 garage can price two different ways on two different lots. Eight things move the concrete foundation cost. The first four are foundation type, square footage, beam depth and spacing, and pier count and depth. The other four are rebar or tendons, the select fill the soil report calls for, the floodplain elevation, and truck or drill-rig access. We do not publish a concrete foundation price per square foot, because a number given before the soil report is a guess. Ask for the free written estimate instead. Every one of those eight items gets its own line, priced for your lot and your sealed plan. For a garage, shop or addition, the slab-specific cost questions are answered on our concrete slabs page.

How thick does a house foundation need to be, and does it need rebar or post-tension?

Thickness is the least of it in Houston. A stiffened slab gets its strength from a waffle grid of grade beams running under the surface. The slab itself is usually 4 to 6 inches on a grade-supported foundation and 4 to 8 inches on a structural slab over piers. On a grade-supported slab the beams only have to bite six inches into competent soil or compacted fill. Beam depth and spacing come off the sealed plan. For reinforcement, a reinforced concrete foundation here uses Grade 60 rebar in a single or double mat. Post-tension tendons are half-inch, seven-wire strands rated at 270 ksi, pulled with a hydraulic jack and locked with wedge anchors. Our structural mixes run 3,000 to 4,500 psi. The engineer picks the system and seals the plan, which matters if you are worried about being upsold.

Do I need a permit and an engineer for a new foundation in Houston?

Yes to the permit. Inside city limits it comes from the City of Houston. Outside city limits the permit comes from the Harris County Engineering Department on Fannin, and Fort Bend, Montgomery, Brazoria and Galveston counties all run their own offices. Houston plan review wants the concrete strength, beam sizes and bar layout on the foundation sheet before it issues the permit. The building official can require a soil test on any lot where expansive soil is likely, and expansive soil sends the design to a Texas PE under IBC 1808.6. A floodplain lot in the county needs a PE no matter what. Houston also wants a legal form survey in the inspector's hand at the first structural inspection. On commercial jobs Houston issues a Foundation Only Permit, so the foundation can start while the building is still in plan review. East of Highway 146 in Harris County, and in Galveston, Brazoria and Chambers counties, the TDI windstorm inspector checks the steel and anchor bolts before we pour. Texas does not license concrete contractors, so ask for the insurance certificate and the engineer's letters instead. We pull the permit and book every inspection.

Are cracks in a new concrete foundation normal in Houston?

Hairline cracks are normal. Concrete shrinks as it cures, so we saw control joints to put those cracks where we choose. A structural crack looks different. It is wide, one side sits higher than the other, doors stick and the floor goes out of level. Stair-step cracks in brick veneer mean one part of the foundation moved and another did not. Houston has a few drivers of its own. The clay swells and shrinks with the weather, and this city averages just under 52 inches of rain a year. Trees cause most foundation repairs here, then plumbing leaks. University of Houston researchers mapped more than 300 surface faults in Harris County, and parts of the region sank more than 9 feet in about forty years from groundwater pumping. If a foundation has already moved, see foundation repair. For chipped or spalled surfaces, see concrete repair and restoration. Call (832) 576-3278 and we will look at it.