What is a Tree Protection Zone (TPZ)?

A Tree Protection Zone (TPZ) is the designated area around a tree that must be preserved to ensure its health and stability. Development sites often require tree protection zones to comply with Australian Standard AS 4970-2009.

✅ How to Calculate TPZ Radius?
The TPZ radius is determined using the Diameter at Breast Height (DBH):

TPZ=DBH×12TPZ = DBH \times 12TPZ=DBH×12

Example: If a tree has a DBH of 50cm, the TPZ radius will be 600 cm (6m).

📌 Why Tree Protection Matters?
✔️ Prevents root damage and ensures tree health
✔️ Essential for trees on development sites
✔️ Protects the tree trunk and structural root zone (SRZ)

📍 Keywords Used: tree protection zones (5/5-7), TPZ radius (1/1-3), structural root zone (1/4-7), Australian Standard (1/3-7), tree trunk (0/1)

🌱 Structural Root Zone (SRZ) & Major Encroachment

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The Structural Root Zone (SRZ) is a critical area that must remain undisturbed to maintain tree stability. Unlike the TPZ, which protects the entire tree, the SRZ radius is smaller but more vital for structural support.

How to Calculate SRZ Radius?

The SRZ radius is calculated using this formula:

SRZ=2.6×DBHSRZ = 2.6 \times \sqrt{DBH}SRZ=2.6×DBH​

💡 Key Considerations:

• The root buttress of mature trees must be protected.
• Multi-stemmed trees require additional assessment.
• Major encroachment into the protection zones may require tree removal.

🛠️ Using the TPZ Calculator – Free Web App Based Tool

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Our free web app-based TPZ Calculator helps developers, arborists, and planners calculate tree protection zones (TPZ) and structural root zone (SRZ) instantly.

🔹 Features of Our TPZ Calculator

✅ Calculates TPZ radius & SRZ radius in seconds
✅ Works for multi-stemmed trees & large specimens
✅ Helps assess area encroached for planning approval
✅ Provides results in diameter measurements or circumference

💡 How it Works:
1️⃣ Enter the DBH (Diameter at Breast Height)
2️⃣ View the TPZ and SRZ radius instantly
3️⃣ Assess encroachment to determine construction impact

📏 Assessing Encroachment on Trees in Development Sites

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The TPZ Calculator helps identify the encroachment level on a tree’s protection zones. Builders and architects can use this tool to determine whether their projects fall within acceptable limits.

Encroachment Calculation Features:

🔹 Allows users to adjust the TPZ radius and encroachment area
🔹 Calculates how much of the ground area is affected
🔹 Displays overlapping buildings within the TPZ

Important:
🚨 If more than 10% encroachment occurs, alternative tree protection measures must be implemented.

🌍 How This TPZ Calculator Supports Australian Standards (AS 4970-2009)

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This calculator is based on the Australian Standard AS 4970-2009, ensuring compliance with Standards Australia requirements.

📌 Why Use This Tool?
✔️ Tree protection zones TPZ calculations ensure site safety
✔️ Meets Australian Standard guidelines
✔️ Prevents illegal major encroachment on tree areas

If you have any query just follow this page and book an appointment with us and we can talk about it.

🚀 Get Instant TPZ & SRZ Results – Try the Calculator Now!

💡 Plan smarter, protect trees, and stay compliant

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