Core service

Slab Foundation Repair.

A slab sits flat on the same clay that swells in spring and shrinks in a Central Texas drought, so the concrete has nowhere to hide from soil movement. GroundLock measures exactly how far it has drifted, then carries it on steel driven past the clay entirely.

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Pour a concrete pad straight onto Houston Black clay and you have built a structure that lives and dies by the weather. These Blackland Vertisols carry plasticity index values from the 40s into the 60s, the "very high" expansion bracket, which means the ground under your floor can gain volume after a wet stretch and give it back the moment July bakes it out. A slab has no crawlspace to absorb that; the soil pushes the concrete around directly, and the cracks you see at door corners are the receipt.

The fix is not patching the cracks or pumping mud under the low spot. It is reaching the part of the ground that does not care what season it is, then transferring the slab's weight onto that. On Central Texas soil that means galvanized steel piers driven through the active clay to load-bearing strata, with a precise elevation survey first so the plan matches the actual deflection rather than a sales estimate.

Two kinds of ground, two kinds of trouble

Where your home sits relative to the Balcones Escarpment changes the whole problem. East of it, across the Blackland Prairie through Schertz, Cibolo, and out toward Seguin, the expansive clay runs deep and the active zone, the band of soil that actually shrinks and swells with the seasons, commonly reaches eight to twelve feet below grade. That is a lot of moving material to clear before a pier finds anything dependable.

West of the escarpment, in the Hill Country pockets of Boerne, Helotes, and the north San Antonio fringe, the story flips: thin residual soil over fractured Edwards limestone. Less clay to swell, but the limestone brings its own surprises, dissolution features and localized voids that produce uneven, unpredictable support. A slab can be perfectly sound on one corner and sitting over a soft spot on the other.

Either way, the failure that damages a slab is differential movement, one region rising or dropping relative to the rest. Edges dry out fastest through evaporation and thirsty tree roots, so they tend to drop first and fan diagonal cracks up from your openings. Less often the perimeter is kept dry while the middle stays damp, and the center heaves into a dome. The pattern tells us where to look; the survey tells us how bad it is.

How a GroundLock slab repair actually runs

Free elevation survey to 1/64 in.

We shoot a grid across your entire floor and map every dip to ±0.01 in. (1/64 in.), so the pier plan is built on measured data, not a walk-through guess.

Engineer-backed pier plan

The elevation map sets how many piers go in, where, how much lift each one targets, and the loading sequence that re-levels the slab without overstressing concrete that is already strained.

Drive galvanized steel piers to refusal

We hydraulically push connected steel sections through the active clay to competent strata, dense caliche or intact limestone, stopping only when the pier refuses to advance under pressure.

Lift, lock, and re-survey

We raise the slab back toward its original elevation in controlled increments, transfer the load onto the piers, then re-survey to document the correction and stand behind it with a lifetime transferable warranty.

What is the problem on Signs the slab

Hairline shrinkage cracks are normal on Central Texas clay; these are the ones that point to real movement underneath:

Diagonal, stair-step cracks fanning from the corners of doors and windows, inside or in the exterior brick
Doors and windows that bind, drag, or stop latching as the seasons turn
Gaps opening between the slab and your baseboards, or between trim and the ceiling
Floors that feel sloped, bouncy, or visibly out of level across a room
Cracking in the slab itself or where the garage floor meets the foundation
Cracks that are widening or offsetting over time rather than holding steady

If you have a post-tensioned slab, read this first

Many newer homes here sit on post-tensioned slabs, where steel tendons are stretched tight inside the concrete. Drilling or cutting one without locating the tendon paths can sever a cable under heavy load, dangerous and expensive.

GroundLock requires documentation of the tendon layout before any pier work that penetrates the slab, which is one more reason the survey and plan come before anyone touches the concrete.

Questions Central Texas homeowners actually ask

My slab has a crack, do I need piers, or is it cosmetic?

Often it's cosmetic. Thin shrinkage hairlines are routine in concrete on these soils. The ones worth worrying about are widening, offset, or paired with sticking doors and stair-step brick cracks. The free elevation survey settles it by showing whether the slab has actually deflected or is just surface-cracked.

Can you re-level the slab without tearing it out and re-pouring?

Almost always, yes. We stabilize and lift the existing slab on steel piers; full replacement is rare and far more disruptive. Recovering elevation and holding it is the goal, and steel piers do that without demolishing your floor.

Why steel piers instead of the concrete pressed piers other companies push?

Depth. East of the escarpment the active clay can run eight to twelve feet down. Pressed concrete cylinders are stacked in short segments and often stop inside that moving zone, so they ride the seasons too. Our galvanized steel sections drive through the clay to load-bearing strata and stay put, on expansive soil, reaching depth is the whole game.

How deep will the piers actually go under my house?

To refusal on stable strata, not a set number. Around here that's often 10 to 25-plus feet, depending on how thick the active soil is before the pier hits dense caliche or intact limestone and stops advancing under hydraulic pressure.

How long will my house be torn up, and can we stay?

Most homes are on site one to three days; larger or hard-to-access foundations run a little longer. Your written plan gives a realistic day count up front, and most families and businesses stay occupied through the work.

What does slab repair around here typically cost?

Most projects land between $4,500 and $14,000, driven by how many piers the elevation map calls for and access. The survey and written plan are free, financing is available, and you'll see real numbers before committing to anything.

Once it's piered, can the slab drift again next drought?

The piered sections are carried on steel below the active soil, so they shouldn't ride the seasons again, that's what the lifetime transferable warranty covers. Areas that weren't piered can still move with the clay, which is why we look hard at how water leaves your lot too.

What should I be doing with watering and grading to protect it?

Keep soil moisture even rather than letting the clay swing wet to bone-dry. Aim for about six inches of fall over the first ten feet away from the slab so water doesn't pond at the edge, and set soaker hoses 18 to 24 inches back from the foundation. Where grading or runoff is the real culprit, pairing the repair with drainage correction keeps the fix lasting.

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