Concrete driveways on flat Wichita lots: pitch, base and joints

Why flat ground makes drainage the first design decision

Much of Sedgwick County and the neighboring counties is level or gently rolling. That is pleasant for mowing and for walking a dog, but it means a driveway cannot rely on gravity alone to shed rainfall. The slab has to be set with a deliberate fall, usually away from the garage and toward the street or a side yard, so that water leaves the surface within minutes of a storm instead of hours.

The amount of fall is a judgment call on each lot. Too little and water lingers in the low spots that every slab develops over time. Too much on a short drive and the transition at the garage door or the street edge becomes a scraping point for low cars. A contractor will usually shoot elevations with a level or laser at the garage floor, the sidewalk and the street before promising a layout.

Pay attention to where the water will end up once it leaves the driveway. On a flat subdivision lot it may run toward a neighbor, collect along a fence line, or sit against the foundation if downspouts empty onto the slab. A good plan names the discharge point, not only the direction.

The clay under the driveway and what it does between seasons

Soils across the Wichita area vary block by block, from sandy ground near the Arkansas River to heavier clays on the higher ground farther from it. Many of those clays are expansive. They take on water during a wet May and swell, then dry and shrink through a hot, windy July and August. A slab resting on that ground gets lifted in some places and left hanging in others.

Concrete handles being pressed on very well and handles being bent poorly. When the support under a driveway changes from one spot to the next, the slab flexes as a car rolls over it, and a crack eventually forms along the line where the support changes. Corners, the edge beside a lawn that gets watered heavily, and the strip beside the house are the usual trouble spots.

The practical fix is not a stronger mix. It is keeping moisture under the slab as steady as possible: a compacted granular base, no low edges that pond water, gutters that discharge well away from the concrete, and irrigation heads aimed at grass rather than at the driveway joints.

Base, thickness and reinforcement, in plain terms

A lasting driveway begins with removing sod, roots and soft organic soil, then placing crushed rock and compacting it with a plate compactor or roller. The base spreads each wheel load across a wider patch of clay and gives water under the slab a way to move out rather than sitting against the underside.

For ordinary cars and small SUVs, residential driveways are commonly poured about four inches thick. If a heavy pickup, a work trailer or a motor home will park there, ask whether the contractor plans a thicker section, at least in the parking area and where the drive meets the street. Edges that take tire traffic are sometimes thickened too.

Steel mesh, rebar or synthetic fibers can all appear in a driveway quote. None of them keeps concrete from cracking. Their job is to hold the pieces tightly together and level if a crack does open. Mesh or rebar only works when it sits up inside the slab on supports, so ask how it will be held in position during the pour.

Control joints and the wind that dries fresh concrete

Every slab shrinks slightly as it hardens, and the shrinkage has to go somewhere. Control joints are grooves, tooled while the concrete is wet or sawed soon after it sets, that give the slab a straight weak line to crack along instead of a random one. The usual rule of thumb ties spacing to thickness: a four-inch slab tends to get joints roughly eight to twelve feet apart, laid out in near-square panels.

Kansas adds a wrinkle here. A dry south wind on a summer afternoon pulls moisture out of the surface of fresh concrete quickly, which can cause fine surface cracks within hours and can force the joint cutting to happen earlier than on a calm day. Contractors in the region commonly pour early in the morning during summer, and they may use windbreaks, evaporation retarders or curing compound to keep the top from drying ahead of the rest of the slab.

The apron, the sidewalk and approvals to check first

The strip of driveway that crosses the parkway and meets the curb, which people call the apron or approach, frequently sits on public right-of-way. Cities in the area may have their own requirements for how that piece is built, who may do it and whether a permit is needed. Those rules differ between Wichita and the surrounding towns, so call the city or county before work is scheduled and ask the contractor who will handle the paperwork.

Homeowner associations in newer subdivisions sometimes review driveway widening, color and finish as well. It is far easier to get that answer before the forms go up than after.

Reading a driveway quote line by line

Two driveway numbers can differ widely and still both be honest, because they often describe different amounts of work. Before comparing totals, lay the quotes side by side and check whether each one addresses the following.

• Removal and hauling of the old driveway, if there is one, and how deep the digging goes.
• The base material and its compacted depth, and what happens if soft spots turn up.
• Slab thickness in the driveway and in any thicker parking or approach sections.
• Reinforcement type and how it is kept at the right height during the pour.
• Joint layout, whether the joints will be tooled or sawed, and how soon.
• The planned fall and where runoff will go once it leaves the slab.
• The finish, curing method, and when sealing is recommended.
• Who arranges any city approval for the apron and when it will be requested.

Concrete driveways on flat Wichita lots — common questions

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