Tree roots that lift and damage sidewalks, roads and other surface structures are a continual source of aggravation for homeowners and public works departments. The cost of this damage runs into the tens of millions every year. Installing root barriers can be an effective way to avoid costly repairs. Barriers are most easily installed at the time of planting before roots get well developed. However installing a root barrier after the fact is usually not a problem with the right materials. Barriers can be made of metal, wood or various types of plastic.
Purchase high-quality root barrier material such as permeable polyethylene panels. These panels are flexible to allow you to easily follow the contours of linear structures such as sidewalks, patios and driveways. Most have interlocking ends which makes installation quite simple for larger projects. Choose a barrier that is at least 30 inches deep.
Dig a narrow trench 36 inches deep and 12 inches wide in preparation for installing the barrier. If you encounter the large roots of an existing tree while digging, contact an arborist for advice. Cutting through these roots may cause irreversible damage to the tree.
Lay out the required number of panels beside the trench and interlock the ends. Backfill 8 to 10 inches of soil into the trench and do not tamp it down or compress it. The soil should be loose well under the bottom of the barrier to encourage the tree to develop deep roots.
Slide the root barrier into the trench and push it down into the loose soil until the top is half an inch above ground level. Keeping the top above ground level is very important to prevent roots growing over the barrier. Finish backfilling the trench being sure to keep the barrier vertical while doing so.