How damaging are tree roots to concrete?
Tree roots are a leading cause of damage to concrete driveways, walkways, and patios. It is the only common natural force that can lift the concrete and cause trip hazards. Tree roots, in search of water, loiter just underneath the concrete surface. When water seeps through a crack or a joint the root begins to swell to accommodate that new-found source of water. As the tree root swells over time, it powerfully lifts the concrete section and suspends it in the air perhaps 1/4 or 1/2 of an inch or so. The suspended section quickly becomes very weak and fragile with no subgrade for support, and will shatter into smaller and smaller sections crumbling around the tree root. So what can you do? Most of the time we remove the affected section of concrete from joint to joint, then we remove all surface roots, and finally we replace the concrete with a rebar grid. The rebar gives concrete the added tensile strength it needs to resist further assaults from the neighboring tree.
