You've stepped over it a thousand times. One panel of the front walk sits a little higher than the next, and your feet just know where it is. Then a delivery driver catches a toe on it, or your mother-in-law does, and now you're worried someone might trip and fall on it and you'd get sued, without even knowing whose problem it is.
It's a fair worry, and you're not the first to have it. One homeowner said they carry a hefty liability policy on the house, but they don't want anyone to get hurt and then get sued. Another was settling an argument at home, where one spouse said the walk was a huge liability trip hazard and the other wasn't so sure. We can tell you how it looks from the concrete side, where the legal side starts, and what to do about the lip before the snow covers it.
Who's responsible depends on where the walk is
One side of my walkway is higher than the other. Am I liable if someone trips?
Possibly, and the answer depends on whether it's your own front walk or the public sidewalk, so check with your city and your insurer. In Denver, maintaining the public sidewalk generally falls to the adjacent property owner, and on your own walk a trip hazard you know about is the kind of thing homeowner's insurers ask people to fix. Either way, a lip you can see is worth fixing or marking before someone catches a toe on it.
We pour and repair concrete, so we're not the people to tell you how a claim would go, and that's a question for your insurance agent. What we can say is how the arrangement usually works. The walk from your driveway or the street up to your door sits on your property, and people coming to the house are walking on it at your invitation. The sidewalk along the street is usually in the public right of way, but in Denver its upkeep generally lands on the property owner beside it, and other metro cities have similar arrangements. The rules vary by city and they change, so the current specifics come from your city, not from us.
The insurer side shows up more than people expect. One homeowner posted that their home insurance had asked them to repair a trip hazard on their walk. Another heard from a friend that their city had ticketed a whole block for uneven sidewalks. A ticket or a letter from the insurer is a long way from a lawsuit, and both are a nudge to deal with a visible lip on your own schedule.
How much higher is too high
Tripping doesn't take much. Accessibility guidelines for public walks treat anything over a quarter inch as a change in level that should be beveled, and anything over half an inch as needing a ramp. Your front walk isn't held to those rules, but they're a useful yardstick for where feet start catching.
Lay a straight board across the joint and measure the gap under the low side. A quarter inch is easy to miss when you're looking down at it and easy to catch with a toe when you're carrying groceries and looking at the door. An inch will catch plenty of people, and once a slab is raised about 2 inches it's a serious trip hazard that makes neighbors walk in the street. Check after dark too, because a walk you know by heart in daylight looks flat under a porch light.
Winter makes all of it worse here. Snow fills the low panel and hides the edge, the shovel catches the lip and chips it, and meltwater pools against the step and freezes overnight. Denver sees around a hundred freeze-thaw cycles a year, so a lip that's half an inch in October can be a little bigger by March if water keeps getting under it.
Why one panel ended up higher
There are two usual causes, and they're opposites. Tree roots push a panel up, and they're the main reason on older walks in Littleton, Englewood and the established Denver neighborhoods, where the walks were poured beside saplings that are now fifty to a hundred years old. The root grows a little each season and lifts one edge a fraction at a time until the panel stands proud of its neighbor.
The other cause is the ground dropping out from under one panel. Much of the metro sits on clay that swells when it's wet and shrinks when it dries, heaviest through Highlands Ranch, Aurora and Littleton, and a panel on a thin base rides that movement. A downspout emptying beside the walk or a sprinkler hitting its edge does the same thing to one corner. The panel nearest the house is a common one to sink, because it sits over soil that was dug out for the foundation and backfilled.
Which one you've got matters because the fix follows the cause. If you push a raised panel down or lift a sunken one without dealing with the root or the water, it moves back. How to tell a slab that has moved from one that has only cracked on the surface is in how to tell if concrete should be repaired or replaced, and the same straight board does the job.
The fixes, from quick to permanent
For this winter, the cheap move is to make the lip visible. Paint the raised edge a bright color, keep the walk shoveled and sanded so the low side isn't hiding under snow, and turn on the porch light. The lip stays where it is, but nobody walks into it by surprise.
Filling the gap with a tube of sealant doesn't help here. Sealant is for narrow cracks where both sides sit level, which is what we went through in filling concrete cracks with a tube from the hardware store. A crack where one side sits higher means something underneath moved, and a bead of caulk across it won't change the height.
A small offset can often be ground down, the way some cities grind down the sidewalks that get like this, tapering the high edge so a foot rolls over it instead of catching. It's quick, it can be done in cold weather, and it leaves the slab in place. It's a good answer when the movement has stopped, but if a root is still growing under it, the lip comes back. The other option people hear about is to mudjack the lower side up, pumping material under the sunken panel to raise it. Homeowners report mixed results. From what we've seen it holds when the ground has settled for good and drifts again when it hasn't, because it doesn't fix the underlying issue on its own.
The permanent fix is replacing the panel that moved. It gets cut out at the joint, the root gets dealt with if it can be cut safely or the base gets dug out and compacted, and new concrete goes in. That's usually a panel or two rather than the whole walk, because the movement tends to stop at a joint. Pour season on the Front Range runs roughly April through October, so a replacement is usually a spring job, and that's what the grinding or the bright paint is buying you time for. You can read more about the kinds of walks we replace on our walkways and sidewalks page, and how the whole range of concrete repair work fits together.
What to do this week
Measure the lip with a board and a tape and take a dated photo of it with a coin beside it for scale. If it's on the public sidewalk, call your city and ask what the current rules are for repairs and permits. If it's your own walk, it's worth a quick call to your insurance agent, mostly so you know where you stand.
Then deal with the water. Point downspouts away from the walk, pull sprinklers back off the edge, and keep it shoveled down to the concrete this winter so ice doesn't sit in the low spot. If there's a tree right beside the raised panel, find out whether it's yours or the city's before anyone cuts a root.
If you'd like someone to look at it
Send us a photo of the walk from a few steps back and a close one of the lip with something in frame for scale, and call us at (720) 782-8086. We'll come out, figure out whether a root or the ground is behind it, and tell you whether grinding will hold or a panel needs replacing, with a written, itemized price. If the right call is to paint the edge, grind it down and wait for spring, we'll say so, and the repair can go on the schedule for when the weather turns.