Why concrete sinks in Wichita
Most sunken slabs around Wichita have two causes working together. Much of the soil in Sedgwick County changes volume as it wets and dries, and the local weather keeps changing how wet it is: a rainy late spring, a hot summer, and about 100 nights a year when the low reaches freezing. Here is what the county's soil survey and 30 years of climate records show, and what that means for a driveway or sidewalk.
Call (316) 688-2584What the soil survey says about Sedgwick County
The USDA's Natural Resources Conservation Service maps every soil in the county and rates how much each one shrinks and swells. The measure is called linear extensibility: how much a moist soil shrinks, as a percentage, when it dries out. Under 3 percent is rated low, 3 to 6 moderate, 6 to 9 high, and 9 or more very high.
We added up the county's current survey by acreage. About three quarters of Sedgwick County's soil area has a layer within five feet of the surface rated moderate or higher, and about a third has one rated high or very high.
| Shrink-swell rating | Share of county soil area | Common soils |
|---|---|---|
| Low | 24% | Canadian, Elandco (river terraces and flood plains) |
| Moderate | 42% | Blanket, Nalim, Farnum, Vanoss |
| High | 23% | Irwin, Tabler, Saltcreek |
| Very high | 10% | Rosehill |
The rating describes the soil, and the soil changes from one lot to the next. Built-up parts of Wichita are mapped as urban land mixed with the original soils, and those mixes include both kinds: high-rated Irwin and Tabler soils as well as low-rated Canadian and Elandco soils. What sits right under a driveway also depends on the fill brought in when the house was built. The soil by town page breaks this down for Wichita and 12 nearby towns.
Source: USDA NRCS Web Soil Survey, Soil Survey Geographic Database for Sedgwick County, Kansas, survey version August 2025. Shares are our calculation from map unit acreage and component percentages, using the highest-rated layer within 60 inches. Water, pits and urban land are left out, and a soil rated exactly 6 is counted as moderate.
How clay moves a slab
Clay takes up water and swells, then shrinks and cracks as it dries. The Kansas Geological Survey describes Kansas soils that "heave and shrink from season to season," cracking foundations, driveways and sidewalks. K-State Research and Extension notes that the pressure is enough to move concrete sidewalks.
A slab does not move evenly with the soil. Its edges and joints get the most water and dry out the fastest, so the soil there shrinks away first and leaves the slab spanning a gap. Rain that finds the gap carries fine soil further under the slab, and the edge drops.
Sources: Kansas Geological Survey, GeoRecord, Fall 2001; K-State Research and Extension, "Clay Soil: It shrinks and swells".
Wichita's weather keeps the soil moving
Wichita averages 34.31 inches of precipitation a year, and it does not arrive evenly. May and June are the wettest months, and more than half of the year's total falls from May through August, when average highs run 88 degrees in June, 93 in July and 91 in August. About 11 days a year bring an inch or more of rain, most of them from April through August. Winter is dry, with about 3.3 inches from December through February combined.
Single years swing much further than the averages. In 2012, Wichita had 12.87 inches of rain from January through April, one of the four wettest starts to a year on record, then only 4.91 inches from May through July, the sixth driest on record for those months. Clay that swelled in the spring dried out through the summer.
Sources: NOAA NCEI U.S. Climate Normals, 1991 to 2020, Wichita Eisenhower National Airport; National Weather Service Wichita, "Wichita goes from wet to dry in 2012".
Freeze and thaw
The low reaches freezing on about 100 nights in a normal Wichita year. On about 87 of those days, the afternoon warms back above freezing. The median first freeze is October 29 and the median last freeze is April 11.
That means water sitting in joints and under slab edges freezes and thaws dozens of times each winter. Each freeze lifts the wet soil slightly, and each thaw leaves it looser and wetter, which is why a slab that looked fine in the fall can show a new lip in the spring.
Source: NOAA NCEI U.S. Climate Normals, 1991 to 2020, Wichita Eisenhower National Airport. Days that thaw are nights at or below freezing minus days that stay below freezing all day.
What it means for your concrete
- Water is the part you control. The soil under your house is what it is, but how much water reaches it is not. Extend downspouts several feet past the slab, aim sprinklers away from joints, and seal the joint between the driveway and the garage.
- Keep moisture steady in a drought. K-State Research and Extension recommends watering the soil a foot or two out from the house during dry spells so the clay does not shrink away from the foundation. Slabs poured next to the house sit in that same soil.
- Fix the cause along with the slab. Leveling fills the void and raises the slab, and the soil stays the same. If water is still getting under the edge, the gap can come back.
- Weight matters on soft ground. Foam adds far less weight under a slab than mudjacking slurry, which can matter where the soil is wet or weak. A contractor can tell you which suits your slab after seeing it.
Look up the soil under your own house
The same data is free to search by address on the USDA's Web Soil Survey. Draw an area of interest around your lot, open the Soil Data Explorer tab, and look up Linear Extensibility under the soil physical properties. It shows which soils are mapped at your address and how they are rated. It will not show fill placed during construction, which is often what sits directly under a driveway or patio.
Questions people ask
Is Wichita soil bad for concrete?
Some of it is hard on concrete. About a third of Sedgwick County's soil area is rated high or very high for shrink-swell, and about a quarter is rated low. Most of the rest is moderate. On any of it, keeping water away from slab edges is what makes the biggest difference.
Why did my driveway drop during a dry summer?
Clay soil shrinks as it dries. When it pulls away from the underside of a slab, the slab loses support, and an edge or corner drops. The gap is usually there for a while before the concrete visibly moves.
Will leveled concrete sink again?
It can if the cause is still there. Leveling fills the void but leaves the soil as it was. Fixing downspouts and sealing joints keeps water out of the new fill and the soil around it.
Does it matter which part of Wichita I live in?
It can. The soil survey maps sandier, low-rated soils like Canadian and Elandco on river terraces and flood plains, and clay-rich soils like Irwin and Rosehill on the uplands. The Web Soil Survey shows the rating for your own lot.
Where we work
We take calls from across Wichita and the surrounding towns in Sedgwick, Butler and Harvey counties.
Common jobs
Driveway Leveling
Panels that dropped at the garage, the street or the sidewalk, raised back into line.
Read moreSidewalk Leveling
Trip hazards on front walks and city sidewalks, raised flush instead of torn out.
Read morePatio Leveling
Patios that tipped toward the house or pulled away from it, lifted back to a proper slope.
Read moreGarage Floor Leveling
Sunken garage slabs and the lip at the door, raised with small holes and little mess.
Read morePorch & Step Leveling
Front steps and stoops that settled away from the door, lifted back up to meet it.
Read morePool Deck Leveling
Settled pool decks and the gap at the coping, lifted with light foam and small holes.
Read moreGet a free estimate
Tell us what is sinking and roughly how big the area is. The contractor will call you back to set up an estimate, and may ask you to text a photo first.
Prefer to talk? Call (316) 688-2584.
Slab dropped at a joint or edge?
Call for a free estimate. Most residential jobs take a few hours.