Concrete trip hazards

The three realistic options

Grinding removes the high edge, cutting the raised side down to meet the low side. It is quick, comparatively cheap, and leaves a visibly different finish where the grinding happened. It does nothing about why the slabs moved and cannot help where the offset is large.

Lifting raises the low side back to meet the high side. It restores the original surface and addresses the void that usually caused the drop. It costs more than grinding and needs the low slab to be in liftable condition.

Replacement takes out the affected panel or panels and pours new. It is the most expensive and the most disruptive, and it is the right answer when the concrete itself is finished or when the offset comes with other damage.

Which to choose

The offset size matters: a small step is a grinding candidate, a larger one usually is not. The cause matters: a slab lifted by a tree root is a different problem from a slab that has settled, and grinding a root-heaved slab buys time until the root grows further.

Appearance matters more on a front walkway than on a side path. And whether the concrete is otherwise sound decides whether lifting is even available.

In the meantime

Where a hazard exists and a repair is weeks away, marking the edge so it is visible — particularly in low light — is a sensible interim step. It is not a fix and does not remove the hazard.

If the hazard is on a public sidewalk fronting your property, responsibility for it may sit with you, with the municipality, or be shared, depending entirely on local rules. That is worth checking with your local authority rather than assuming either way.

Measuring and recording it

Put a straight edge across the joint and measure the height difference at its worst point. Photograph it with something for scale beside it, and note the date. If you have any reason to think the difference is growing, repeat it in a month.

That record does two jobs. It gives whoever quotes the work something specific to price against, and it establishes whether the movement is finished — which decides whether removing the high edge is a fix or a postponement.

Where the hazard is on a route other people use, the record also matters for a less pleasant reason: it shows when you became aware of it and what you did about it. That is a reason to act rather than to monitor indefinitely once you know it is there.

What to ask a contractor

• Is grinding realistic here, or is the offset too large?
• Why did this slab move, and will it move again?
• If we lift it, what happens to the joint appearance?
• Are the neighbouring panels likely to do the same thing?

Common questions