Assessment Results

Tree Protection During Construction

Standards for protecting trees during construction and development activity.

Before reviewing your results, verify how your state governs local authority. States follow either Dillon’s Rule, which limits municipalities to powers explicitly granted by the state, or Home Rule, which allows broader local authority unless specifically prohibited by state law. If you’re in a Dillon’s Rule state, your tree ordinance must follow state-enabling legislation. Check your state statutes, municipal league, or community forestry program to confirm your state’s model.

When developing or revising a tree ordinance, we recommend you work with your community’s legal counsel. Legal counsel will help ensure your ordinance complies with state and local requirements, properly establishes enforcement authority, and can achieve your community's goals, while avoiding potential legal challenges.

Introduction

A construction site is a dangerous place for trees. Equipment can cause long term or lethal damage by breaking branches, cutting vital roots, or compacting soil. If your ordinance includes tree preservation requirements, it is crucial to also include detailed language on how preserved trees will be protected during site development.

The core strategy of tree protection during construction is to assign each protected tree a buffer area where all potentially harmful construction activities are prohibited. The buffer  area is often called the Tree Protection Zone (TPZ) or Root Protection Zone (RPZ) and is either defined by a set distance, the dripline of the tree, or an equation based on the diameter of the tree. The sample language and ordinance examples below demonstrate three levels of complexity for tree protection during construction requirements. 

Key Definitions

Tree Protection Zone (TPZ)

A designated area around a tree (minimum 1.5 times the critical root zone) where construction activities (e.g., excavation, soil compaction) are prohibited.

Construction Impact Assessment

An evaluation by a Certified Arborist to determine potential harm to trees during development and recommend protective measures.

Protective Barrier

A temporary, visible fencing system (e.g., 4' high) installed to enforce TPZ boundaries.

Example Language

Basic

Basic Level

Basic ordinances require minimal measures, such as fencing around trees during construction, to prevent obvious damage. This is an important first step for reducing accidental harm on job sites.

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Basic

Tree Protection During Construction

  1. Protective fencing must be installed around trees on construction sites.
  2. No material storage or vehicle parking is allowed within the fenced area.

 

Examples

Ithica, New York

Ithaca, NY Code of Ordinances. Chapter 306 - Trees and Shrubs, Sec. 306-7. Accessed May 29th, 2025.

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Newport, Rhode Island

Newport, RI Code of Ordinances. Chapter 12.36 - Tree and Open Space Preservation and Protection, Sec. 12.36.120. Accessed May 29th, 2025. 

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Katy, Texas

Katy, TX Code of Ordinances. Chapter 1 - General Provisions, Sec. 1.13.006. Accessed May 29th, 2025. 

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Intermediate Level

Intermediate ordinances define critical root zones, restrict certain activities near trees,  require signage, and instruct monitoring. These standards offer more reliable safeguards for tree health during development.

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Intermediate

Tree Protection During Construction

  1. A tree protection plan, approved by the City Arborist, is required for all development sites. A tree protection plan shall include the following information:
    1. A tree survey completed by an ISA Certified Arborist that correctly identifies the species, DBH, and location of each tree on the property, noting which trees are proposed to be removed and which trees are to be preserved.
    2. Specifications for protective fencing and signage during construction.  
  2. Protective fencing and signage shall be installed at the Tree Protection Zone (TPZ).

Examples

Fayetteville, Arkansas

Fayetteville, AR Code of Ordinances. Chapter 167 - Tree Preservation and Protection, Sec. 167.05. Accessed May 29th, 2025.

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Hartford, Connecticut

Hartford, CT Code of Ordinances. Chapter 28 - Planning and Development, Sec. 28-161. Accessed May 29th, 2025. 

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Shoreline, Washington

Shoreline, WA Code of Ordinances. Chapter 20.50 - General Development Standards, Sec. 20.50.370. Accessed May 29th, 2025.

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Advanced Level

Advanced ordinances mandate pre-construction arborist assessments, advanced root protection (e.g., air spading), and post-construction health monitoring. This ensures long-term survival of trees and minimizes construction impacts.

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Advanced

Tree Protection During Construction

  1. Tree Protection Plan. A tree protection plan, approved by the City Arborist, is required for all development sites. The plan shall include the following information:
    1. Tree Survey. A tree survey completed by an ISA Certified Arborist that correctly identifies the species, DBH, and location of each tree on the property, noting which trees are proposed to be removed and which trees are to be preserved.
    2. Fencing and Signs. Specifications for protective fencing and signage during construction.  
  2. Tree Protection Zone. Protective fencing shall be installed at the Tree Protection Zone (TPZ), with none of the following allowed in this area:
    1. Grading or excavation of any kind.
    2. Storage of construction materials or vehicles.
    3. Garbage or waste of any kind.
  3. Signage. One sign that describes the TPZ regulations shall be installed every 25 linear feet on the protective fencing. The sign shall be posted in English and Spanish.
  4. Enforcement. Failure to comply with this section may result in a stop work order until the site is brought into compliance with this section and the City Arborist can conduct an assessment of the impacted tree.  

Examples

Fort Collins, Colorado

Fort Collins, CO Transitional Land Use Regulations. Article 3 - General Development Standards, Sec. 3.2.1. Accessed May 29th, 2025. 

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Winter Haven, Florida

Winter Haven, FL Code of Ordinances. Chapter 21 - Unified Land Development Code, Sec. 21-185. Accessed May 29th, 2025. 

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Burien, Washington

Burien, WA Code of Ordinances. Chapter 19.26 Tree Retention, Sec. 19.26.090. Accessed May 29th, 2025. 

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Relevant Industry Standards and Best Management Practices

ANSI A300 Clause 13 Tree Risk Assessment (2023): Management During Site Planning, Development, and Construction: Outlines best practices for preserving trees during construction, including pre-construction assessments, root zone protection, and post-construction care. Defines Tree Protection Zones (TPZ) and mitigation for soil compaction.