Question
I live in a planned community in Stuart Florida. Live Oaks are adjacent to the cement sidewalk through out the community.  The sidewalk slabs adjacent to some of the Live Oaks have started to elevate due to the root growth.  Is there any way to prevent this?  Will lifting the slab and cutting the offending root be a temporary or permanent solution?  Any reccomendations?

Answer
Consider installing expansion joints in the sidewalks near trees. This will limit possible sidewalk replacements to just a few sections rather than large areas. Curving and narrowing sidewalk sections near trees might also reduce heaving. Building sidewalks on beds of coarse gravel is also effective at slowing or stopping the heaving. Tree roots will not grow through porous gravel; instead, they grow deeper. The installation of removable or adjustable semi-permanent pavers near trees can serve as alternatives to poured sidewalks. The pavers can be altered when required to compensate for tree root growth.

Install root barriers along the tree-side edge of the sidewalk. The barrier will force tree roots to grow deep below the sidewalk, thus preventing heaving. Barriers can be made of plastic or geotextile fabric. It should extend one foot deep and at least 5 or 6 feet in both directions from the point on the sidewalk edge closest to the tree.

Whenever trees are root pruned, there is always some risk of tree failure. Many factors are involved. Tree species, age, size, site conditions, existing problems, vigor and extent of pruning are just some of the factors. Mature trees are less tolerant of root pruning than young trees, trees on sites exposed to high winds are less tolerant than sheltered trees, and trees with defects or poor general health are not good candidates for root pruning. The closer to the trunk the roots are pruned, the greater the effect on the tree. A rule-of-thumb is to make all cuts at least a distance of three times the trunk diameter from the outside of the trunk. Thus, root pruning of a tree with a trunk diameter of two feet should be done no closer than six feet from the trunk. Make all cuts even farther from the trunk for trees which are judged intolerant of root pruning.