Tree Assessments

Tree assessments are undertaken to provide an arboricultural assessment and report on a tree or trees health within a development site.

Tree assessments are undertaken to provide an arboricultural assessment and report on a tree or trees health within a development site. These reports may be required by council during the planning process to ascertain which trees may be impacted on by proposed works or planned for removal. Reports may include information on:

  1. The species, origin, dimensions, health and structure of the trees and their appropriateness for retention
  2. Any recommendations regarding the management of the trees including any tree protection requirements for retained trees that may be impacted during development
  3. Any offset requirements for trees to be removed
  4. Habitat or heritage value of the trees on a site
  5. Potential impacts of development on the trees within a site
  6. The potential risks of a tree to assets or people within the property or development site.

Assessments of trees utilise methodologies detailed in the Australian Standard AS4970-2009: Protection of Trees on Development Sites. Within development sites trees will generally be allocated a Tree Protection Zone (TPZ) which is a distance from the stem set aside for the protection of a tree’s crown and roots to provide for the viability and stability of the tree. The TPZ is radius from the centre of the tree calculated by measuring the Diameter at Breast Height (DBH) of the tree and then multiplying it by 12. The DBH is a measurement of the nominal diameter of the tree trunk, at 1.4 metres from ground level, determined from the circumference of the trunk, divided by pi (π).

Tree Protection Zone (TPZ)

Encroachment Calculator

(AS4970 Protection of Trees on Development Sites)

Diameter of tree at 1.4m above ground. For 90cm enter '0.9'

DBH (m) *

Calculated TPZ (m)

The radius (R) of a circle taken from the centre of the trunk.

Diameter of trunk above buttress (m). For 85cm enter '0.85'

Trunk diameter*

Calculated SRZ (m)

The radius (R) of a circle taken from the centre of the trunk.