Tree, sidewalk, and hardscape solutions

The idea is to create and maintain a system that can accommodate tree roots while minimizing damage to the infrastructure. Listed below are some suggestions and solutions that have worked for communities. Remember that sidewalks settle, rise, and crack for a variety of reasons including soil characteristics, freezing and thawing cycles, inappropriate installation, tree roots, and age. Many concrete sidewalks are only meant to last about 25 years so they deteriorate with or without trees.


How close to the trunk can roots be cut?

Well, the answer appears to depend on who you ask. For mature trees, some experts recommend not cutting roots closer than 6 to 8 inches from the trunk for each inch in trunk diameter. That means stay at least 10 feet away from a 20 inch tree! Others are more realistic and state that we should root prune no closer to the trunk than a distance equal to 3 times the trunk diameter, preferably 5 times the trunk diameter.



Slabjacking to fix cracked sidewalks

Slabjacking (AKA mud jacking or leveling) raises the section of a sidewalk so it is even with a portion that was lifted by tree roots. Slabjacking consists of pumping a new base material (grout) under the sunken concrete, raising and supporting it. Slabjacking one slab takes about 30 minutes and cost about $40 to raise one section of sidewalk. This compares favorably with concrete replacement which can cost up to about $275 per section.



Reinforcing concrete to reduce cracking

Concrete walks that are reinforced with steel as in the photo can resist cracking from soil settlement, soil heaving and root expansion underneath. As roots grow under the slab they are less able to lift the slab because it is very heavy. If the slab weighs enough roots will deform instead of lifting the slab.