- Protecting trees during construction helps save both trees and property from potential damage.
- When steps are taken to protect trees on construction sites, the risk of damaging or destabilizing trees is reduced.
- It is important to keep the crown, branches, and trunk clear from direct contact and injury by equipment, materials, or disturbances during construction.
- Tree protection measures should also preserve the roots and soil from compaction and disturbance, this is called a Root Protection Zone.
Protecting Trees During Construction
Two practical methods of tree protection are the Prescriptive Path and Performance Path. One of these methods should be implemented before any ground-disturbing activity.
The Prescriptive Path method of tree protection establishes a root protection zone and blocks this zone from construction activities. When it is not practical to establish a root protection zone to the specifications of the Prescriptive Path method, you may use alternative measures to modify the root protection zone, called the Performance Path.
- Modified measures when it is not practical to establish a root protection zone to the specifications of the Prescriptive path.
Whenever possible, hire a certified arborist to lead tree identification, evaluation, preservation, monitoring, and follow-up activities. Please see Arborist Report Guidelines for more information on situations where an arborist report is required.
Before any construction or tree protection activities begin, you must determine what trees or groves on the site will be preserved during construction. See Tree Requirements for Building Permits to determine what trees must be preserved or mitigated on your site.
Prohibited Activities in the Root Protection Zone
Some construction activities are prohibited in any part of the root protection zone.
These activities include:
- Construction activity involving vehicle or equipment access (unless the access is on an existing street or driveway)
- Excavation or fill
- Ground disturbance
- Impervious surfaces
- In-ground irrigation systems
- Other work activities
- Proposed buildings
- Storage of equipment or materials (including soil)
- Temporary or permanent stockpiling
- Underground utilities
Encroachments in the Root Protection Zone
Construction activities may not encroach:
- on more than 25% of the Root Protection Zone area.
- The encroachment may not be closer than one half of the Root Protection Zone radius.
Please refer to the following Tree Code Information Guide:
Installation of landscaping required by Title 33 is allowed within the root protection zone and is not an encroachment.
Root Cutting, Root Removal and Root Disturbances
Cutting a large percentage of a tree’s roots can be dangerous. Most large tree roots, those over 4 inches in diameter, are structural roots that support the tree. If large roots are disturbed or removed, the tree may fall over and/or decline or die. Roots over 4 inches in diameter should not be cut. If cutting a tree’s roots is unavoidable, a certified arborist must approve and oversee the root cutting.
Heritage Trees and Development
Heritage Trees must be protected during development. Work on or around any Heritage Tree requires the property owner or applicant to schedule an assessment meeting with the City Forester by calling Urban Forestry.
For permit approval, Planning and Zoning needs to see the recommendations that Urban Forestry provides for the tree transferred on to the tree preservation plan. Take a copy of the current plan to the onsite meeting with Urban Forestry. The onsite meeting should be scheduled early in the development application process.