Driveway Crack Repair in San Antonio: Which Cracks Matter and How to Fix Them

Driveway crack repair in San Antonio starts with one question: is the crack moving? Nearly every driveway, patio and walkway eventually cracks. Most cracks are cosmetic. The ones worth acting on are the ones that move, trip people, hold water or send water toward the house. Cracks inside your home's slab foundation are a separate question with a different fix.

Why flatwork cracks

Concrete shrinks as it cures and moves with temperature swings. Much of the San Antonio area also sits on clay soil that swells when wet and shrinks in drought, which lifts and drops slabs unevenly. Control joints, the straight grooves cut or tooled into a slab, are there so cracks form along a planned line. Cracks that wander away from the joints usually trace back to one of these:

• Thin or poorly compacted base under the slab
• Water running off roofs or downspouts and softening the soil
• Tree roots lifting a section
• Heavy vehicles on a slab built for foot traffic
• Joints spaced too far apart

The National Ready Mixed Concrete Association's guidance on cracking concrete surfaces says it is not possible to produce completely crack-free concrete, and that most random cracks appearing at an early age, although unsightly, rarely affect the structural integrity or service life of the slab. It traces most cracks to design and construction practices: missing or poorly placed joints, poor subgrade preparation, too much water in the mix, improper finishing, fast drying and little or no curing.

Soil is the other half of the story. A USDA NRCS soil sheet describes the Blackland Prairie as extending from north of Dallas south to San Antonio, with Houston Black clays that shrink and swell markedly as moisture changes. During dry periods, the official series description records cracks in that soil roughly 1/2 to 4 inches wide. You can check the mapped soils for your own lot on the USDA's Web Soil Survey. The Texas Department of Licensing and Regulation's bulletin on expansive soils explains that wet clay heaves and dry clay settles, and it names surface drainage, plant choices, sprinkling practices and long-term maintenance as the ways to limit swings in soil moisture.

Common crack types and what they tell you

NRMCA's guidance on crazing notes that craze cracks are rarely more than 1/8 inch deep, do not affect the structural integrity of concrete and are generally not a sign of future deterioration. They can look worse over time as dirt settles into them, but they don't need structural repair.

Which cracks matter

Usually cosmetic:

• Hairline cracks that aren't growing
• Cracks that run along a control joint
• Fine surface crazing

Worth a closer look:

• Cracks wide enough to catch a coin edge, or visibly wider than last season
• One side higher than the other, which creates a trip hazard
• Sunken sections where water ponds after rain
• Cracks near the house that tilt water toward the foundation
• Broken corners and edges on a driveway apron

A simple way to track movement: mark each end of a crack with a pencil line and the date, and photograph it with a coin for scale. Check again after a wet spell and a dry spell.

House slab cracks are different. Cracks inside the home, along with doors that stick, gaps at trim or stair-step cracks in brick, call for a structural engineer or foundation specialist, not a flatwork repair.

Driveway crack repair options compared

Replacement usually runs joint to joint, so the new section ends at a clean line. Ask how the new section will be tied to the old one and how the base will be prepared.

Sealing a narrow, stable crack

Sealing keeps water out of the base, which matters on clay soil. For QUIKRETE Self-Leveling Polyurethane Sealant, Quikrete's instructions for repairing and sealing cracks give these product-specific steps:

1. Open the crack with a chisel to at least 1/4 inch and remove crumbling concrete, leaving the edges vertical or shaped like an inverted V.
2. Brush out all loose material.
3. For cracks or joints wider than 1/4 inch, press a backer rod into the crack before sealing.
4. Run the sealant slowly along the crack, let it settle, and clean up any excess right away.

Follow the cure times and temperature limits on the product label. Sealant keeps water out but leaves height differences as they are, so a crack with a raised edge still needs grinding, lifting or replacement. Asphalt driveways take different crack fillers and patching; for asphalt paving work, see parking lot paving and striping.

Lift, replace or start over?

• Lift a section that sank but is still in one piece, and fix the water or base problem that let it drop.
• Replace a section when it is broken into pieces, offset enough to trip on, or sunken and holding water.
• Replace the whole driveway when most panels are broken or offset, or when the slab drains the wrong way along its full length.

When new concrete goes in, hold it to the same standard as any new slab. NRMCA's guidance on joints in slabs on grade calls for maximum joint spacing of 24 to 36 times the slab thickness, about 10 feet for a 4-inch slab and no more than 15 feet, with near-square panels, grooves at least one quarter of the slab thickness, and isolation joints where driveways meet walks, curbs and other fixed points. It also notes that wire mesh will not prevent cracking; it tends to keep cracks and joints from opening up. NRMCA recommends curing new slabs for at least 3 days, so ask how the crew will cure yours, especially during a San Antonio summer.

Permits: your lot vs. the City's right-of-way

DSD's no-permit list includes sidewalks and driveways inside your property line, so a typical driveway or patio replacement on your own lot doesn't need a DSD building permit. Historic, conservation or corridor districts can still restrict design and materials.

The edge of the street is different. The City's Public Works Department says permits are required to operate in the City's right-of-way, and its right-of-way permit types list covers removal, repair, modification or installation of sidewalks, driveway approaches and curbs and gutters. The approach where your driveway meets the street, and a public sidewalk, may be in the right-of-way rather than on your lot. Your survey or plat shows the line; when in doubt, ask Public Works before demolition starts. Public Works also requires companies to register in its Right of Way Management system and meet its insurance and bonding requirements before requesting a permit, so ask whoever does the work who will pull it.

Outside San Antonio city limits, cities such as Leon Valley and Live Oak run their own permit offices, so check with that city before work at the street edge.

Replacing a section means breaking out concrete and digging base, and Texas811 says Texas law requires contacting 811 at least two business days before excavating, not counting weekends and holidays, even in your own backyard.

Slowing down new cracks

• Point downspouts and gutters away from slabs
• Regrade low spots where water ponds
• Seal cracks and joints so water can't reach the base
• Water evenly near slabs in dry spells so one edge doesn't dry out far more than the rest
• Keep heavy trucks and trailers off walkways and patios
• Ask about root barriers when large trees are close

What a good estimate covers

A written scope should say which sections are sealed, patched or replaced, how much demolition and haul-off is included, base preparation and reinforcement for new sections, joint layout, finish and any sealer, and who handles right-of-way permits and utility locates.

Related planning

Planning a new surface instead? See how stamped concrete patios in San Antonio are planned: patterns, prep and sealing, from building to last on clay soil with base prep and control joints to pattern and color choices, sealing, upkeep and permit basics. Or compare options in deck vs. patio vs. pergola. If the fence along the driveway is failing too, check fence repair or replacement, and for larger projects, see when San Antonio building permits apply and who applies. For flatwork scope and project management, see concrete services, and for a new patio, deck or pergola, see our patio, deck and pergola services.

Next step

If you want a second opinion on which cracks need attention, or a written scope for driveway repair in San Antonio, call (210) 796-3695, request an estimate or book an estimate consultation with veteran-owned 214 Veteran Solutions.