Tree Roots Lifting Your Sidewalk or Driveway — Options That Don't Kill the Tree

A sidewalk slab heaved an inch or two by a thick root, or a driveway cracking along a root line, is one of the most common tree-versus-concrete conflicts. The short answer: you usually do not have to choose between the tree and the walkway — a combination of selective root pruning, a root barrier, and rebuilding the slab to work around the roots fixes the hazard and keeps the tree alive, as long as you do not cut too much of the root system at once.

Why roots lift concrete

Roots grow where water, oxygen, and loose soil are — which is exactly what sits under a sidewalk or driveway. A root does not "push" concrete up with great force so much as it grows thicker year after year in a space that was not built for it, gradually lifting the slab above it. The problem gets worse when the slab sits on compacted, shallow soil that forces roots to grow near the surface instead of deeper.

Cutting the offending root out completely feels like the obvious fix, but it is often the worst one: a large root is a structural anchor and a major water and nutrient supply line. Removing it can destabilize the tree, open it to disease, and — if several large roots are cut — kill it outright or make it a falling hazard in a storm.

Option 1: Grind or ramp the slab (small lifts)

If the lift is under about an inch and the slab is otherwise sound, grinding the raised edge down to level, or adding a small asphalt or concrete ramp over the lip, removes the trip hazard without touching the tree at all. This is the cheapest fix — often a few hundred dollars — but it is temporary: the root keeps growing, and you will likely repeat the work in a few years. It buys time while you plan a longer-term fix.

Option 2: Selective root pruning plus a root barrier

For a moderate lift, an arborist can prune the specific offending root — cutting it cleanly, at a point where it will not destabilize the tree — and install a root barrier: a rigid panel buried vertically between the tree and the walkway that deflects future root growth downward and away from the slab. The rule of thumb arborists use: never remove more than about 25 percent of a tree's root system in one job, and never cut roots close to the trunk (stay at least several feet out, depending on the tree's size).

After pruning and the barrier, the lifted slab section is removed and repoured, often slightly rerouted or with a flexible joint that tolerates minor future movement. This is the most common lasting fix for a single lifted section.

Option 3: Reroute or redesign the walkway

When the tree is large, beloved, or protected, the smartest fix may be to move the walkway rather than fight the roots: curve the path around the root zone, bridge over the roots with a raised boardwalk or a slab on a flexible base, or use pavers or permeable paving that can flex and be individually reset as roots grow. Pavers in particular are forgiving — a lifted paver can be pulled up, the root trimmed, and the paver reset, without breaking a whole slab. This option costs more up front but avoids repeat concrete work and keeps a mature tree intact.

When removal is actually the right call

Sometimes the tree has to go: if it is already diseased, structurally unsound, or a species notorious for aggressive surface roots planted inches from the slab, and the slab keeps failing despite barriers. Also check local rules — many cities require a permit to remove a street tree or a tree above a certain size, and sidewalk repairs on public property may be the city's responsibility, not yours. Call your city or county before cutting anything on a sidewalk easement.

What to do first

Start with an arborist's assessment, not a concrete contractor's saw. The arborist can tell you which roots are safe to prune, whether the tree is healthy enough to tolerate the work, and whether a barrier or reroute makes more sense. Then get the concrete work quoted with that plan in hand — the two trades need to coordinate, and the order matters: prune and barrier first, then repour.

On ZIP Pros — "Pros in your ZIP" — describe the problem once and get free quotes from local pros, with real starting prices shown up front. Mention the tree type if you know it, how much the slab has lifted, and whether the sidewalk is on public property — that tells the pro whether an arborist, a concrete crew, or both are needed.