Is a Sinking Driveway Dangerous?

Short answer: It can be. A sinking driveway is dangerous when there is a void under the slab that a car could break through, when a panel dropped suddenly after heavy rain, or when it left a trip edge over ¼ inch where people walk. Slow, even settling usually isn't urgent, but it gets costlier to fix.

OKC Driveway Repair Co. levels and repairs sinking driveways across Oklahoma City, and we triage urgent ones the same day. Whether a sinking driveway is dangerous depends on why it is sinking and how fast. Most settling is slow and safe for now. A few patterns are not, and those are worth knowing before the next storm.

Urgent: keep vehicles off and call today

• A void you can see or reach under the slab. The slab is spanning empty space. It can crack and drop under a wheel without warning, most often at an edge.
• A sudden drop after heavy rain. A panel that sank overnight usually means water is actively carrying soil out from under it, from a washout or a broken pipe.
• New cracks running parallel to an edge a few inches in, especially with soil washing onto the street. That is the edge losing support.
• A trip edge where people walk. The ADA Standards allow only a ¼-inch vertical change on an accessible route (§303.2), and require a bevel up to ½ inch (§303.3). A new lip at a front walk, a business entrance or a shared drive is a fall hazard today.
• Water running into the garage or toward the foundation because a panel now slopes back toward the house.

For any of these, see emergency driveway repair. Same-day response is available during business hours.

Not urgent, but don’t wait years

• A panel that has dropped half an inch to an inch, evenly, over several seasons.
• A small, stable step at the garage joint.
• Cracks under ¼ inch with both sides level.

These are slow settling, usually from Oklahoma’s shrink-swell clay or loose backfill beside the house. The Kirkland and similar clays under much of the metro are rated high for shrink-swell. They pull away from the slab in drought and swell back when wet, a little at a time.

What happens if you leave it

Slow settling is not dangerous today, but it changes the repair:

1. Water starts pooling on the low panel and running into the joint.
2. The base softens and voids grow, so the panel keeps dropping.
3. The panel cracks under its own weight and car loads once it loses support.
4. A liftable panel becomes a replacement. Leveling an intact panel costs about $3 to $15 per square foot; replacing a broken one costs more and takes a week before you can drive on it.

What to do now

1. Measure the drop with a level across the joint, and photograph it with the date.
2. Check the water. Is a downspout aimed at the low spot? Does water stand there after rain?
3. Turn downspouts away and keep heavy trucks off the low panels.
4. Re-check after the next heavy rain. Any change is a sign to call.

Our guide to why driveways sink explains the causes, and the free damage assessment sorts your situation in two minutes.

Bottom line

A sinking driveway is dangerous when there is a void, a sudden drop or a trip edge where people walk. Slow, even settling isn’t urgent, but it gets more expensive the longer water keeps reaching the base. If you’re unsure, call (405) 442-4044 and describe what you see.