Problems
Concrete trip hazards
One slab sits higher than the next and someone is going to catch a foot on it.
A trip hazard is a vertical difference where two pieces of concrete meet. One panel has settled, or one has been lifted by a root, and now there is a step where there should be a continuous surface. Most of them are on walks, and how sidewalks are built and repaired covers who is normally responsible for putting one right.
It is the most common reason homeowners stop tolerating a concrete problem and start getting quotes — usually after somebody stumbles. The choice at that point is nearly always between grinding the lip off and lifting the panel, and the two leave you with different surfaces and different lifespans.
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 the low panel raises it 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 — the void, not the slab, sets a lifting price — 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?
How we know what this page says
Each of these is something this page says. What follows is why we say it, what we had to assume, and what would change our mind — so you can weigh it rather than take it on trust. How we grade what we publish.
Grinding a raised edge removes the trip hazard without addressing why the edge rose.
Established practice This is how the work is normally done, and it is not seriously contested among people who do it. It usually reflects material behaviour or long-standing method rather than opinion.
Evidence considered
- Grinding removes material from the high side, which changes the profile and not the position.
- Where the underlying movement continues, the difference in height returns.
- As a hazard-removal measure specifically, it is well established and not contested.
Still to establish
- Soil movement — partly, on your own
- Slab thickness — partly, on your own
- Reinforcement — partly, on your own
- Vertical displacement — you can check this yourself
Why we say this, and when it may not apply
It is a legitimate and often sensible piece of work, and it is also frequently sold as a repair. Both things are true and a homeowner should know which they are buying.
What we had to assume
- That there is enough material to remove without exposing reinforcement or thinning the section unduly.
- That the hazard rather than the level is the thing being addressed.
When this may not apply
- Where the movement has genuinely stopped, grinding may be the whole of the necessary work.
- Where the height difference is too large, grinding cannot reach it without excessive removal.
What would change it
- A dated observation showing whether the height difference is still increasing.
- Establishing the thickness available at that point.
- Establishing whether reinforcement sits close to the surface there.
Established practice does not mean this: It does not mean the practice is right for your property, that any particular contractor follows it, or that following it guarantees an outcome. Established practice describes what is normal, not what will happen at your address.
Common questions
How big does an offset have to be to matter?
Standards for public walkways vary by jurisdiction and are set locally, so there is no single number that applies everywhere. Practically, people catch their feet on differences much smaller than they expect, particularly at night and particularly where the surface is otherwise flat and the eye is not looking for a step.
Is grinding a permanent fix?
It permanently removes that particular high edge. It does not address the movement, so if the slab is still settling the difference returns. Ask the contractor whether they think the movement has finished.
Work it out, or judge the quote
Related guides
Uneven concrete
Surfaces that no longer sit flat or flush — and the difference between a low slab and a bad pour.
Read more →Sunken concrete
A slab that now sits lower than it should — almost always a ground problem, not a concrete problem.
Read more →Concrete leveling
Raising settled slabs back toward their original height instead of tearing them out.
Read more →Sidewalks
The public-facing strip — where responsibility for repairs is not always yours.
Read more →Walkways
Narrow, frequently walked, and the place trip hazards actually cause falls.
Read more →