The May edition of Tree Link featured the article, “Introduction to Tree Protection During Site Development,” and the June edition discussed Critical Root Zones. Part three of this tree protection series focuses on the most effective tool for protecting trees in the field, tree protection fencing.

Tree protection fencing is any type of continuous physical barrier that keeps people, vehicles, equipment and materials out of tree protection zones on construction sites. A tree protection fence helps prevent disturbance and damage to tree trunks, roots and branches IF it is properly selected, installed and maintained. Common tree protection fencing materials range from highly visible orange plastic mesh to semi-permanently installed chain link fencing.

Why? Where? How?

Local policies and ordinances should clearly define tree protection requirements and why those are important to the community, along with enforcement protocols, incentives and penalties for non-compliance. Many communities develop standard notes and plan details for tree protection to reduce ambiguity over requirements.

Installation of tree protection fencing should be one of the first permitted actions taken on a construction site to prevent damage right from the beginning of the project. Properly planned tree protection fencing should align with approved tree protection areas, typically encompassing the Critical Root Zone, as discussed in last month’s Tree Link. Establishing tree protection measures early and maintaining them for the duration of construction minimizes the risk of damage not only to tree roots and the soils that they grow in, but trunks and branches as well.

Tree protection fencing materials vary in size, durability and cost. Most types of fencing materials may serve as tree protection fences as long as the material is durable enough to withstand the scope and duration of construction activities. In general, silt fences, orange safety fences, snow fences, or thin gauge welded wire fencing materials are considered too flimsy to reliably protect trees, especially on construction sites with large, heavy equipment. Thicker gauge steel fencing, such as chain link fencing, securely mounted to well-anchored steel posts is recommended. Fencing should be a minimum of 4′ tall and posts should be no further than 8′-10′ apart.

Tree protection fencing is most effective when it is highly visible, marked with flagging or other high-visibility material. Fenced Tree Protection Areas should be clearly designated as such with signs posted at regular intervals. Signage may also include contact information so that questions or concerns can be addressed in a timely manner.

Kirkland TP detail

Or Else…

Routine inspections are recommended for monitoring construction site activities to ensure that fencing is maintained in compliance with the approved tree protection plan. Trees are not protected when heavy equipment is parked or materials are staged ON TOP OF or BEHIND the protection fencing! Follow-up inspections may be needed to verify compliance if violations occur.

  • Minor violations may be addressed through written notification by City officials, and may include requirements to repair or restore inadequate or compromised fencing.
  • Depending on City code, chronic violations may result in a combination of written warnings, fines and/or fees, in addition to restoring protective fencing or mitigating damages.
  • Major violations that result in significant damage to trees may require prescriptive remediation, restoration or corrective actions to mitigate for damages in addition to fees or fines; this may include pruning, tree removal and replacement, or corrective soil treatments.
  • When violations are extreme, chronic or not addressed adequately, stop work orders may be issued, permits may be revoked or certificates of occupancy may be withheld until tree protection violations are satisfactorily rectified. Some communities issue criminal citations for the most egregious offenses.

It’s important to protect valuable urban tree resources while expanding your community’s built resources; from risk management to stormwater management all the way through to climate change adaptation, it just makes good $en$e.