Tree Protection Zone
/tree proh-TEK-shun zohn/🌲 Arboriculture●● Intermediate
Also known as: TPZ, critical root zone, CRZ
The tree protection zone (TPZ) is a setback area around trees designated for preservation during construction. It is typically calculated as a radius from the trunk based on trunk diameter (e.g., 1 foot of radius per inch of DBH, or 12× DBH in Australia/UK). The TPZ should be fenced with rigid barriers and no digging, grading, material storage, or heavy equipment operation is allowed within it.
Etymology
From Old English trēo (tree) + Latin protegere (to protect) + Greek zōnē (belt, girdle)
Example
“The TPZ was fenced at 1 foot per inch of DBH before any site grading commenced.”