Be conscious of any trees that could get damaged when you start working on a new project.

The City of Austin preserves the natural resources that make Austin beautiful. To keep Austin gorgeous, the city protects large trees and their roots.

Regulated Size Trees

Certain tree sizes are regulated in Austin and require a special permit to remove or impact. You will need a Tree Ordinance Review Application (TORA) if your project:

  • involves a tree of any species that is 19 inches or more in diameter (59.6904 inches around),

and requires you to:

  • remove the tree,
  • or do work near the critical root zone.

How to Measure a Tree

To calculate a tree’s diameter, measure the circumference of the tree from 4.5 feet above the ground (diameter at breast height or DBH), and divide by Pi (3.14). Trees smaller than 19 inches in diameter are not regulated.

Diagram showing where to measure trees based on trunk characteristics

  • If the tree is on a slope, measure 4.5 feet above grade from the high side of the slope. 
  • If the tree has irregular swelling in the trunk, measure 4.5 feet above grade above or below the swell(s). 
  • If the tree is a multi-stemmed tree
    1. Measure all the stems at 4.5 feet above grade. 
    2. Take the largest stem diameter, and add it to half of the subsequent stem diameters. 
      For Example: A Cedar Elm has two stems measuring 18 inches and 16 inches at 4.5 feet above grade. The larger stem is 18 inches, so take half of the subsequent stem diameter (16 inches / 2 = 8) and add it to the largest stem measurement. Calculate multi-stem diameter: 18 inches + 8 inches = 26 inch diameter. 
  • If the tree is a leaning tree, measure at 4.5 feet above grade within the center area of the leaning tree.

What Impacts Require a Permit?

  • Proposed removal of a regulated tree; and/or,
  • Proposed impacts in the full critical root zone of regulated trees; and/or,
  • Proposed pruning in excess of 25% of the canopy.

Tree Preservation Criteria

  • A minimum of 50% of the critical root zone of all regulated trees must be preserved at natural grade, with natural ground cover. 
  • No cut or fill greater than 4 inches allowed within the 1/2 critical root zone. Piers with suspended slab may be permitted within the 1/2 critical root zone on a case by case basis dependent upon tree impact and at City Arborist staff discretion.
  • No impacts allowed within 1/4 critical root zone.

Read the full Tree and Natural Area Preservation requirements, Section 3 of the Environmental Criteria Manual.

Digging Into Critical Root Zones

A tree’s critical root zone depends on its size. Larger and older trees have bigger critical root zones that must be built around. Even if your completed project won’t be within 10 feet of a tree, bringing in construction equipment may affect its health. For example, a large cement truck driving on your property can damage a tree’s root system since it is just 4 inches underground.

To understand where you can and can’t build around trees, imagine that there are three development impact zones around the base of the tree. We’re using a tree with a 20 inch diameter in the example below.

critical tree root zone diagram

The Critical Root Zone

In this example, the critical root zone extends 20 feet from the base of the tree. You can dig into the ground in the outer half of the critical root zone (in this example: between 10 to 20 feet from the base of the tree or the green zone).

1/4 Critical Root Zone

The 1/4 critical root zone (in this example: the red zone) extends 5 feet (1/4 of 20 feet) out from the base of the tree on the ground level. You will damage the tree’s roots if you dig in this zone.

1/2 Critical Root Zone

The 1/2 critical root zone (in this example: the yellow zone) lies between 5 and 10 feet from the base of the tree. You can only dig 4 inches into the soil in this zone.

Heritage Trees

You may not be able to remove heritage trees because they are highly protected by the City of Austin in order to preserve their natural beauty. Navigating the critical root zone of heritage trees may be difficult if the trees are 24 inches or more in diameter and one of the species on the list below.

  • All Oaks
  • Arizona Walnut
  • American Elm
  • Bald Cypress
  • Bigtooth Maple
  • Cedar Elm
  • Eastern Black Walnut
  • Pecan
  • Texas Ash
  • Texas Madrone

You may be able to apply for a variance to have the heritage tree removed if the heritage tree is dead or is a hazard to life or property.

Contact the City Arborist about your project if you have a heritage tree in your yard.