Every neighborhood has one. The sidewalk panel that dropped an inch, or the one a tree root shoved up, and now there's a lip that catches toes, stroller wheels, and the snowblower blade.
You've probably heard four different opinions on how to fix it. Some of them are right for your walk and some aren't.
Here's how to sort it out, with the honest pros and cons of each option, including the ones we don't do.
Step 1: Measure the Lip
Lay a straight board or level across the joint so it rests on the higher panel and sticks out over the lower one. Measure from the bottom of the board straight down to the low panel.
A useful yardstick is the ADA standard for accessible walking surfaces: vertical edges over 1/4" should be beveled, and anything over 1/2" needs a ramp. Your front walk isn't held to ADA rules, but if the lip is over half an inch, someone is going to catch a toe on it.
Your city may use its own measurements for marking defects, so if you got a notice, go by the numbers on it.
Step 2: Figure Out Which Panel Moved
This decides everything else. Stand back and look down the whole run of sidewalk.
| Clue | Sunken panel | Heaved panel |
|---|---|---|
| Compared to the rest of the walk | One panel sits lower than the line of the others | One panel sits higher than the line of the others |
| Nearby | Downspout, sump outlet, low spot, recently removed tree | Large tree within reach of its roots, or wet soil that frost pushes up |
| Edges | Gaps or washed-out soil along the sides | Hump or crack running over a root |
| Over time | Drops a little more after wet springs | Rises slowly year after year (roots) or worst in late winter (frost) |
Sunken panels are what foam lifting is built for. Heaved panels are trickier, because no lifting method can push concrete down. We cover heave in detail in our tree roots article, but the short version: you either grind the high edge, lift the panels around it to blend the lip into a slope, or replace it.
The Four Fixes, Cheapest to Most Expensive
| Fix | Relative cost | How long it lasts | Best fit | The catch |
|---|---|---|---|---|
| Patch a ramp over the lip | Lowest | Short. Thin edges tend to chip and pop loose with freeze-thaw and shovels | A temporary fix until you can do one of the others | Looks like a patch. Feathered edges break down fast outdoors. |
| Grind the high edge | Low | Permanent for that lip, but nothing stops the panel from moving again | Small lips, roughly an inch or less, on either sunken or heaved walks | Leaves a visible ground strip. Doesn't fix the cause. Thins the concrete at the edge. |
| Lift the low panel (foam) | Moderate. More than grinding or patching, a fraction of replacement | Long-term, as long as water isn't still washing soil out underneath | Sunken panels that are mostly in one piece | Can't lower a heaved panel. Badly broken panels may not be worth lifting. |
| Replace the panel | Highest | Longest, if the base underneath is fixed too | Broken, crumbling, or badly heaved panels | Saw cutting, tear-out, forms, and days of curing. A new panel on the same bad base can settle again. |
Option 1: Patch a Ramp Over the Lip
You can trowel a patching or ramp compound over the low side to fill in the step. It's the cheapest fix and a reasonable weekend project.
When it fits: As a temporary safety fix. If the lip is a hazard right now and you can't get the real fix done until next season, a patch buys you time.
When it's the wrong choice: As a permanent repair. A ramp patch has to be feathered thin at the edge, and thin material doesn't hold up long in Wisconsin. Water gets under it, freezes, and pops it loose. Snow shovels and plow blades catch the edge. And it does nothing about why the panel moved.
Option 2: Grind the High Edge
A contractor uses a diamond grinder or saw to shave the raised edge down into a gentle slope. It's quick, cheap, and works on both sunken and heaved situations because it only touches the high side.
When it fits: Small lips on walks that are otherwise in decent shape. Grinding is a good honest fix for a minor offset, and if that's all you've got, you may not need us at all.
When it's the wrong choice: Bigger offsets. The more you grind, the longer and thinner the ground slope gets, and you can grind through the surface into the stone underneath. It also leaves a strip that doesn't match the rest of the walk, and if the panel is still sinking or rising, the lip comes back.
Option 3: Lift the Low Panel
Foam lifting raises the sunken panel back up to meet its neighbors. We drill a few 5/8" holes (about the size of a dime), inject high-density structural foam underneath, and the foam fills any voids first, then raises the panel in small, controlled increments. The holes get patched, you can walk on it right away, and most residential sidewalk jobs are done in a couple of hours.
Why it usually wins on a sunken panel: It fixes the actual problem (the panel dropped) instead of hiding it, and the foam is waterproof once cured, so it won't wash out next spring.
When it's the wrong choice: The panel is heaved, not sunken. The panel is broken into several loose chunks. Or there's a broken pipe or drain line under the walk that will keep washing soil out until someone fixes it.
Option 4: Replace the Panel
Saw out the bad panel, fix the base, form it, and pour new concrete. Done right, it's the most complete fix.
When it fits: The panel is broken into pieces, badly crumbling, or heaved too far for grinding or blending to make sense. Replacement is also often the answer when roots have to be cut and a barrier installed anyway.
When it's the wrong choice: When the panel is in one piece and just sank. You're paying for tear-out, new concrete, and curing days to fix something a lift handles in an afternoon. And if nobody fixes the base or the water source, the new panel can sink right along with the old one.
Quick Pick Guide
| Your situation | Usually the best fix |
|---|---|
| One panel sank, still in one piece | Lift it |
| Small lip, panels otherwise fine | Grind it |
| Big lip from a sunken panel | Lift it |
| Big lip from a root-heaved panel | Lift the neighbors to blend it, or replace (see the tree roots article) |
| Panel broken into pieces | Replace it |
| Need it safe this week, real fix later | Patch now, plan the permanent fix |
Whose Sidewalk Is It?
If it's the public sidewalk along the street, check before you hire anyone. Wisconsin law lets cities, villages, and towns order the owner of the property next to a sidewalk to repair it, and if the owner doesn't, the municipality can do the work and add the cost to that property's tax bill. Many northeast Wisconsin communities put sidewalk repair on the homeowner this way. In Green Bay, for example, the city's sidewalk page says property owners are responsible for the sidewalks in front of their property.
Rules vary by community, so call your city or village and ask:
- Who's responsible for the sidewalk in front of your house.
- Whether you need a permit for work on the public sidewalk.
- Which repair methods they accept for the panels they've marked, if you got a notice.
- Whether a terrace tree caused it. If a city-owned tree in the strip between the sidewalk and street pushed the panel up, some communities handle that differently.
Keep It Level Once It's Fixed
- Watch the edges. If soil along the side of the walk is washing away, backfill it and get grass growing.
- Caulk between the panels. Every open joint is a funnel for April snowmelt. We caulk sidewalk joints, and it's often added right after a lift.
- Send roof and sump water somewhere else. Extend downspouts and point the sump discharge away from the walk. Most sunken panels trace back to water.