Understanding the Protected Root Zone of Your Trees
The Protected Root Zone is also known as the PRZ and it
comes into play when trees need to be protected during construction. When any
type of construction work is being done around existing trees, an area that
protects the root areas of the tree from damage must be determined and fenced
off for the protection of the tree(s). The amount of space needed for the tree
protection area needs to be determined.
The Protected Root Zone of your trees can be identified as
follows:
- Measure the diameter of the trunk at chest height, or 4.5 feet above the ground. Then measure outwards from the tree trunk 1.25 feet for every inch of trunk diameter, which results in the critical root zone.
- This measurement should be to the nearest inch. To do this, either wrap your tape measure around the tree’s trunk and divide that number by 3 or hold a yard stick up to the trunk and approximate the distance.
- Multiply the number by 1.5 for a mature or stressed tree or by 1 for a young, healthy tree. Show the result in feet.
- Measure that distance from the trunk of the tree. The area within this radius is the Protected Root Zone.
Construction can work with existing trees when the Protected
Root Zone is recognized and identified. In addition the builders, architects,
and whomever else is involved in determining the placement of the house to have
the most minimal impact on the existing trees. Professional arborists should be
involved in determining the best course of action and then later to ensure that
the Protected Root Zone is enforced. In addition an arborist can help maintain
the health of your trees today and in the future. Make sure tree care
professionals are working with you for the health of your trees.
