A good rule‑of‑thumb is to remember that up to 35% of a tree is underground. Also that the roots will go out more than the height of the tree. Using this, we can see that the pine (seen to the left) will have roots extending under the driveway to the adjacent lawn.
These roots were suspected to be causing the lifting of this driveway. When cut‑outs in the concrete were removed, this was confirmed. The mass of roots is clearly visible (see photo to right and upper right).
This could have been avoided with a root barrier installed along the left side of the driveway. This tree can still be saved by pruning the roots along the left side of the driveway and then installing a root barrier.
Large roots should not be cut closer to the tree than 3 times the diameter of the trunk. Preferably, a minimum of 5 times the trunk diameter is best for tree health and stability.
An certified arborist should be consulted before cutting large roots close to a tree or large quanities of roots on a single tree.
Once exposed, the roots can be cut. After cutting the roots, the biobarrier is installed and backfilled. The biobarrier keeps new roots from growing thru it and back into those undesired areas.
