What Is A Root Barrier?
It's a barrier that is used to protect something from the damage that can be caused by root growth. You severe the roots that are growing toward the object you want to protect and place an artificial barrier in place to stop the root from growing that direction any longer.
What depth of barrier should you use? Jim recommends using 3ft barriers as the typical 18 inch barrier allows the tree to grow underneath the barrier and cause damage.
What shape barrier should you use? A half moon shape barrier will encourage the roots to grow in the opposite direction where as a straight barrier allows the roots to grow around the outside edges.
What type of barrier should you use? A high density plastic barrier is what Jim recommends instead of the Bio barriers available. Bio barriers allow moisture to go through the barrier which encourages the roots to continue to grow towards the barrier. Plastic barriers stop moisture and force roots to turn in order to continue to grow.
Is it dangerous to your tree? Typically you only sever about 20% of the roots when you instal a root barrier so you won't cause serious damage to your tree by installing a barrier.
Never root barrier a tree that is older than the home it is next to! The soil around the house is used to the amount of moisture that the tree is removing. Installing a root barrier on a tree that is older than the house will increase the moisture in the soil and can cause your house to raise higher leading to more problems.