Why a slab moves at all
A slab-on-grade house sits on concrete poured directly on the ground. The concrete is strong, but it is only as steady as the soil beneath it, and that soil does not stay the same size.
The LSU AgCenter describes Louisiana’s heavy clay soils as swelling when they are wet and cracking open when they dry — the kind of movement that makes building foundations difficult.
The trouble is when that movement is uneven. If one part of the slab drops while another holds or rises, the walls, doors, and finishes above it have to absorb the difference — and that is where the symptoms show up.
What it looks like from inside
Published lists of foundation warning signs line up with what slab owners tend to notice first:
- Doors and windows that stick, swing open on their own, or stop latching.
- Cracks running diagonally from the corners of doors and windows.
- Cabinets or countertops pulling away from the wall.
- Drywall nails backing out in a line.
- A floor that slopes toward one side of a room or the house.
Any one of these alone can be ordinary — hairline drywall cracks are often just the house settling in. Several of them together, or one that keeps getting worse, is the pattern worth an evaluation — the signs of foundation problems checklist covers what to record. If cracks are what you are seeing, the foundation crack repair page covers how to read them.
What the evaluation should record
A slab evaluation is a survey, not a glance. Before anyone talks about piers, the specialist should measure how far the floor has moved and in which direction, mark where the cracks are, and look at what the water is doing around the house. The findings belong on the quote as their own line, so you can see what the recommendation is based on.
Ask to see the elevation readings. A drawing of the floor plan with the high and low points marked is the single most useful thing to have when comparing two specialists’ plans.
How a slab is lifted
When a slab has settled, the published method is to install piers beneath it, down to soil that will carry the load. Steel push piers are driven with a hydraulic ram; helical piers are turned into the ground with a torque motor. Each pier is tested, then jacks raise the slab and brackets lock it at the new height.
Published national ranges put steel push piers at $990 to $1,350 per pier and helical piers at $3,500 to $4,400 per pier. How many a house needs, and where, comes from the evaluation — see foundation piering for how a pier plan should read.
The pipes in the slab
Water and sewer lines run through or under most slabs. A slow leak there keeps the soil wet in one spot, which is exactly the uneven moisture that moves a slab — and a slab that moves can in turn crack or shift the pipes running through it. Plumbers publish guidance recommending a plumbing test before foundation work for that reason. Ask the specialist whether one is part of their process and who orders it.
The water outside
Piers fix where the slab sits; they do not change what the soil around it is doing. LSU AgCenter guidance on foundations is to slope the ground away from the house and drain groundwater before it gets to the foundation. If the yard still sends water toward the slab, that belongs on the quote too — see drainage work.
How the slab quote should be laid out
- 1Evaluation findingsWhat was measured and found — elevation readings, crack locations, construction type, likely cause.
- 2Drainage / moisture correctionGutters, grading, downspouts, or crawlspace moisture work that addresses why the soil is moving.
- 3Structural repairPiers, shims, or sill and beam replacement — with counts, locations, and depths stated.
- 4Finish / cosmeticDrywall, brick, trim, and door adjustments after the house moves — priced on its own line.
On a slab, the structural line should say how many piers, of what type, where on the plan, and to what depth or test standard. “Piering as needed” is not a number you can compare.
Slab repair, in published ranges
| Job | Published range | Scope | What moves it |
|---|---|---|---|
| Minor crack repair & basic waterproofing | $1,900–$3,800per job | Shreveport | Crack count and length, and whether moisture work is included. |
| Major repair (underpinning, piers) | $2,300–$23,900per job | Shreveport | How many piers, how deep, and how far the house has to come back. |
| Steel push pier | $990–$1,350per pier | National | Depth to bearing and access around the house. |
| Helical pier | $3,500–$4,400per pier | National | Depth, soil, and the load at that point. |
Rows marked “Shreveport” come from published Shreveport cost guides. Rows marked “National” come from published national cost guides, not Shreveport figures. These are published ranges, not quotes and not our prices — we do not price or perform work. A real number comes only from a specialist evaluating the house.
Worked examples are on the Shreveport foundation repair cost page.
Permits. Ask your specialist who pulls the permit.
Slab repair questions
How much does slab foundation repair cost in Shreveport?
Published Shreveport ranges run $1,900 to $3,800 for minor crack repair and basic waterproofing and $2,300 to $23,900 for major repairs that need piers or underpinning. The evaluation decides which of those your slab is.
Can a cracked slab be fixed without lifting it?
Sometimes. A crack from shrinkage that is not moving may only need sealing. A crack that keeps widening, or one that comes with sticking doors and sloping floors elsewhere in the house, points to movement — sealing it without dealing with the movement only hides it for a while.
Should the plumbing be checked before slab repair?
It is worth asking about. A leak under a slab keeps water going into the soil beneath it, and a slab that moves can damage the pipes that run through it. Ask the specialist whether they recommend a plumbing test, and whether it happens before the work, after, or both.
Is it settlement or is the slab pushing up?
It can be either. Clay soil can drop as it dries and swell as it takes on water, so part of a slab can sink while another part rises. That is one reason the evaluation should record elevations across the whole floor rather than at one spot.