Piedmont concrete lasts as long as the ground and water allow

What Triad concrete is resting on

Dig a few inches into almost any yard between Winston-Salem and Burlington and the soil turns a deep red or orange. That color comes from iron in a clay subsoil that formed as the ancient rock of the Piedmont weathered in place. Further down, the clay grades into saprolite, a soft, rotten-looking rock that still carries the banding of the stone it used to be. It is ordinary ground for this part of North Carolina, and a well-built slab can sit on it for decades.

The catch is moisture. Clay near the surface drinks up water during long wet spells, turns greasy and loses bearing strength. In a dry, hot stretch it gives the water back and pulls away from whatever rests on it. A slab is rigid and tolerates squeezing very well, but it has little tolerance for bending. When one corner or one edge loses support and a car rolls over it, the slab flexes a little, again and again, until a crack opens along the line between firm ground and soft.

Construction adds its own layer of risk. Builders grade lots by cutting high spots and pushing soil into low ones, and they shove excavated dirt back against the foundation once the walls are up. Unless somebody packed that loose material down a few inches at a time, it goes on sinking for years. It explains why so many driveways in the region dip at the garage, why front stoops tip toward the door, and why patios behind newer homes slowly start draining the wrong way.

Trees are the third factor. Older neighborhoods in Greensboro, High Point and Winston-Salem are shaded by big oaks and other hardwoods whose roots run well past the drip line. A thick root just under a walk can lift it, and a thirsty tree can dry and shrink the clay under part of a driveway during a dry summer.

Humid summers, icy winters and fast summer storms

The Triad climate is hard on concrete in a few specific ways. Summers are long, hot and muggy, and a July cloudburst can send a sheet of water across a yard before the lawn has a chance to absorb it. That water has to go somewhere, and on rolling lots it often runs along or under the edges of slabs, carrying fine soil with it. Remnants of tropical storms occasionally push through as well, soaking the ground for days.

Winters are milder than in the mountains or farther north, but freezing nights followed by thawing afternoons are common, and the region is known for ice storms and freezing rain more than for deep snow. Water held in the pores of concrete expands as it freezes, and repeated cycles can flake off the top layer, a condition known as scaling. Road brine and salt spread during winter storms make that worse when cars carry them home onto driveways and garage aprons.

Two habits help. An air-entrained mix, which is seeded with microscopic bubbles that act as pressure relief when pore water turns to ice, is the norm for outdoor flatwork anywhere winters bring regular frost. Sealing exterior concrete, especially decorative finishes, slows the water and salt that cause scaling and makes shaded slabs easier to clean when humidity lets mildew grow.

Five hidden steps that separate good pours from bad ones

On pour day, a careful job and a careless one can be indistinguishable. Come the third or fourth January, the first still lies flat while its twin is breaking apart. Nearly everything that explains the gap is buried under the concrete by the time you see it, so it has to be discussed while the job is still on paper.

The ground and the base

Topsoil and roots should be removed, soft pockets dug out, and a layer of crushed stone placed and compacted with a plate compactor or roller. On Piedmont clay, a dense, well-packed stone layer spreads weight and gives trapped water a way out, and no other single item on a quote buys as much lifespan.

Thickness where the weight is

Driveways and patios for ordinary use are commonly poured around four inches thick. Pads that will carry a loaded pickup, a camper or a trailer are often thicker, and edges that take traffic may be thickened too. A good quote says what thickness is planned and where.

Joints placed on purpose

All concrete shrinks as it hardens, and it cracks somewhere. Control joints tell it where. A common rule of thumb puts them no farther apart, in feet, than two or three times the slab depth in inches, and they have to be deep enough and early enough to beat the concrete to the crack.

Reinforcement in the right place

Steel mesh, bar and fiber additives keep broken pieces locked together and level with each other. None of them keeps a slab from cracking in the first place, and mesh trodden down onto the stone during the pour does almost nothing. Ask what will hold it up at mid-depth.

Curing, slope and drainage

On a humid July day, fresh concrete can still dry too fast at the surface, so it should be kept damp, covered or treated with curing compound. The finished slab should pitch water away from the house and off the concrete, and downspouts should empty somewhere other than a slab edge.

Request an estimate visit

Send the property address and a line about the project: a new pour, a replacement, or a slab that has begun to crack or sink. A reply follows to arrange a visit.

The six kinds of concrete work homeowners ask about

Requests from Triad homeowners tend to land in a handful of groups, and plenty of them overlap. Tearing out a driveway is a natural moment to redo the path to the front door. A new back patio usually needs a way down from the deck or the kitchen door. Stamped patterns, integral color and exposed stone can be added to most kinds of flatwork, each carrying its own maintenance. Repair gets a page to itself, since the opening question there is whether the old concrete deserves another chance at all.

A short homework list before anyone visits

Nobody expects precise answers here. Jotting down a few notes, even rough ones, lets the first phone call or email cover more ground and makes the site visit sharper.

• Your street address, plus any neighborhood association or historic overlay that signs off on exterior work.
• A plain description of the job and a rough size. Walking the edges and counting strides is accurate enough.
• Your biggest load, whether that means a riding mower, a work van or a fifth-wheel camper.
• Anything that has to be broken up and hauled away first: an old slab, cracked blacktop or a gravel bed.
• Where the gutters drain and where puddles linger after a thunderstorm.
• The look you are leaning toward, whether a simple broom texture, a stamped pattern, a tint or exposed stone.
• Anything in the way of a mixer truck, like a narrow gate, a steep bank, a septic drain field or low wires.

Anything that touches the street, a new curb cut or apron for example, is worth raising with the city, town or county before a start date is chosen, along with any association in your neighborhood. Guilford, Forsyth and Alamance each set their own requirements, and so do the towns inside them.

From the first message to cured concrete

After your note comes in, expect a call to pick a day when the contractor can tour the yard with you. That walk is what turns an idea into a scope. Soil type, the fall of the land, the paths rainwater takes, the reason an old slab broke, and the route a loaded mixer would use all get looked at in person. What looks like a routine swap in a phone picture sometimes needs a drain or a deeper base once the ground itself has been checked.

Next you should receive the proposal in writing. The helpful ones list square footage and depth, the stone base, the steel or fiber, where joints will be cut, the surface texture, whether tear-out and disposal are covered, and which direction water will run off. Put competing proposals side by side on those lines, because two different bottom lines for one yard frequently describe two different pieces of work.

Once you say yes, the date floats with the forecast. Hard freezes and soggy weeks push concrete work back, and July jobs tend to begin around sunrise. When the forms come off, plan on a few days before people walk across the new surface and a longer wait before any car does, with exact timing coming from the contractor for your particular slab.

Three counties, many kinds of lots

The bulk of inquiries come from Guilford, Forsyth and Alamance. Inside each county you will find century-old city blocks, subdivisions graded last year and farms with long gravel lanes, and the dirt under two neighboring houses can behave quite differently. That is why the property visit counts for more than any map.

Concrete questions Triad homeowners ask first