Foundation Underpinning Boerne, TX.

What the ground under your slab is actually doing

Boerne's active zone, the band of soil that swells and shrinks with the weather. Usually runs only four to eight feet deep, far shallower than the clays farther east. Shallow does not mean harmless. Even a plasticity index in the moderate 25-to-45 range pushes real swell pressure into a slab when moisture swings between Hill Country drought and a fast storm runoff.

Caliche seams and limestone outcrops interrupt that thin soil at random, so the bearing surface under a single house can change by several feet over a short horizontal run. Many lots on these slopes were cut and filled to build, and that engineered fill settles at a different rate than the native rock beside it, adding one more variable to an already irregular profile.

The result is movement that is dramatic in spots and quiet in others. Diagnosing it by eye is guesswork; the only way to know how far a slab has dropped, and where, is to measure it. That is why every job starts with a survey rather than a sales pitch.

Signs your Boerne foundation is moving on its bearing

Differential settlement between rock and soil tends to announce itself in a few specific ways:

• Stair-step cracks in brick veneer or block, often heaviest at one end of the house where a footing has lost its support
• Diagonal cracks radiating from the corners of windows and doorways
• Doors and windows that bind seasonally, tight in the wet months, loose in drought
• Floors that slope, bounce, or feel uneven from one room to the next
• Gaps opening where walls meet trim, ceilings, or the slab at the garage
• Patched cracks that keep reopening because the underlying movement was never addressed

How GroundLock underpins on Hill Country rock

Every project opens with a free elevation survey accurate to ±0.01 in. (1/64 in.) across the whole structure. That map tells the engineer precisely where the slab has deflected and by how much, which sets pier count, pier placement, and the lift sequence. Spacing is structure-specific, uniform six-foot centers in one zone, tighter four-foot centers at a badly dropped corner, never a rule of thumb.

We drive galvanized steel piers hydraulically, using the building's own weight as reaction force, and keep driving each one until the equipment registers consistent refusal on competent limestone or dense gravel below the active zone. Depths vary with the rock, often 10 to 25-plus feet. Pressed-concrete piers rely on friction in the soil column and frequently stop short inside the moving clay, which is a liability where rock depth shifts by feet over a few yards. Because water drives so much of the movement, lasting results often pair the lift with drainage correction and erosion control on these rocky, fast-draining lots.

Most homes and buildings stay occupied throughout, crews work from the exterior and access points. Typical projects run $4,500 to $14,000 depending on pier count, access, and drainage, the work is backed by a lifetime transferable warranty that follows the property at resale, and financing is available.

Boerne foundation underpinning questions