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Pre-Purchase Inspection

Preliminary Assessments

Impact Assessment

 Protection Plan


A preliminary arboriculture assessment is a report generated by a qualified consulting arborist.

Through collecting quantitative and qualitative information on the site’s existing trees, a preliminary assessment will contain important information for everyone involved in the development of the site.

Crucially, suitability for retention must be assessed for every tree on site. Not all trees will be suitable for retention, and some may need to be removed before construction begins.

Conversely, some trees may be an asset to your development and could be incorporated into your designs to provide amenity and value to the future occupants. Certain trees may also be protected by state or even national legislation. Knowing this before you start designing the layout of your site is extremely important.

To demonstrate this point, imagine you skip a preliminary assessment only to find out you have damaged a protected tree on your site. Such a scenario may result in a Stop Work Notice, costing you valuable time and money as a result. On top of this, some councils have the authority to issue fines for damage to protected trees, which can be substantial, depending on the value of your tree.

Put simply, a preliminary assessment ensures the smooth approval of your development permit.

Read on to find out how we can help speed up the development process and save you money.


A preliminary arboriculture report requires an accurate location of all trees on site.

When in the development stage should the preliminary assessment occur?

If you are thinking about a developing a site that has any trees, engaging a qualified consulting arborist should be one of your very first steps. It’s vitally important to contact us before you engage an architect or designer, as the preliminary arboriculture assessment contains important information that will affect the layout of your site. Additionally, the report can be used to justify tree removal, understand biodiversity offsets, and can help you to understand the limitations of the site.

What information is required to produce a preliminary arboriculture assessment?

Before we begin, we require an accurate location log of all trees on site. We can conduct the survey ourselves, or this can be completed by a surveyor.

What information is provided in a preliminary arboriculture report?

Our preliminary reports are comprehensive, and contain both qualitative and quantitative considerations. To begin with, we provide an assessment of suitability for retention which has two components:

  • Tree significance, which accounts for the size, age, visual impact, amenity and conservation or heritage values
  • Sustainability in the landscape which accounts for the health and structural condition of the trees.

Basic morphometric data such as Diameter at Breast Height (DBH) and Diameter Above Buttress (DAB) are collected, which are used to generate Tree Protection Zones (TPZs) and Structural Root Zones (SRZs) for each tree. These measurements are essentially a setback distance from each tree and the starting point for your designers to plan the layout of the site.

With all this in place, this information can be used again during future reports provided by the consulting arborist.

What is assessed?

The two most important things to assess in the preliminary arboriculture assessment is the significance and sustainability of each tree as it relates to the landscape.

Put simply, we ask two questions:

  1. Is this tree important or valuable?
  2. Is it in good enough condition and healthy enough to remain viable for an extended period of time?

To answer these questions, we employ the Significance of a Tree Rating System (STARS) and Sustainability Retention Index Value (SRIV), which have been produced by the Institute of Australian Consulting Agriculturalists (IACA).  Additionally, these methodologies also contain a consideration of the trees’ life expectancy.

Our reports assess your trees’ vitality and structural integrity while taking valuable measurements.

What are the outcomes?

The final result of this process is an arborist report. In this report, all high value and healthy trees are identified in a site plan, which can then be incorporated into your designs for the site. In essence, it describes what can and can’t be cleared for development.  After all, why would you try and retain a tree that is falling apart and most likely be removed in the futrue. Instead, retain the ones that have a long life expectancy and will provide real value to you and the future occupants of the site.

Why is a preliminary arboricultural so important?

Developers, architects and designers all greatly benefit from a preliminary arboriculture report, as it assists in:

  • Smoothing-over the development application approval process
  • Identifying areas which can be cleared for development
  • Identifying encroachment limits to trees which are to be retained
  • Avoiding costly stop work notices
  • Avoiding costly redesigns

Additionally, the arborist report is also a valuable tool in preventing the unintended loss of valuable community assets. That is, our reports help:

  • Retain the value that trees provide for the future users of the site
  • Prevent the loss of habitat, heritage or community values
  • Prevent the loss of benefits which are conferred on the wider community

What can happen if we miss this step?

The principal behind the saying “measure twice, cut once” applies to more than just cutting wood.

If you don’t have a preliminary assessment done by a certified arborist, you are likely to run into trouble with your development application. If your designers do not have the correct information beforehand, they may produce a design which will have unacceptable impacts to some trees from the councils perspective. The council will likely ask you to consult an arborist, and we will be forced to tell you the bad news: re-design.

What’s more, if you start work without an understanding of Tree Protection Zones you may end up unintentionally damaging trees. Damaging trees to a point where they are either unviable or structurally compromised will result in the removal of the trees.  If a tree is protected by legislation, you may be responsible for reparations in the tens of thousands of dollars, and incur a poor reputation with the council and community.

Avoid this costly process and provide your designers with the correct information.  This will also make the next step go much smother, an arboriculture impact assessment, which details the impact the designs will have on the trees.

How does our report align with the Australian Standards?

Our reports are created in line with The Australian Standard Protection of Trees on Development Sites (AS 4970). Section 2.3.3 outlines all of the information required for a preliminary assessment.

Basic morphometric data is collected and used to generate Tree Protection Zones (TPZs) and Structural Root Zones (SRZs) for each tree.

Can any arborist prepare a preliminary arboricultural report for me?

The minimum requirement for preparing arboricultural reports is a Certificate 5 or Diploma in Arboriculture (Australian Qualification Framework Level 5), as this is the minimum qualification accepted by local councils.  Making sure your arborist has at least has this qualification is important, otherwise the report may be refused by council.

Our consulting arborists have much higher qualifications (click here to see our Team page). Tasmanian Arboriculture consultants are more than experienced and fully prepared to meet your needs.

Okay, I’m convinced – how do we make this happen?

A preliminary arboricultural assessment is a must when considering development on your property. It can significantly speed up the design and development application process by providing the right information to all those involved.

It’s our role to provide best practice, evidence based arboriculture reports for your development application. Our professional tree care and management advice will help you make important decisions regarding the health, safety, and maintenance of your arboricultural assets.

Contact us for a chat about how we can help.

Colin is the director of Tasmanian Arboriculture Consultants

Blog written by Colin Fry

Colin is the director of Tasmanian Arboriculture Consultants Pty Ltd and our lead consulting arborist. He comes with an academic background and more than 20 years in practical tree care. As a registered member of Arboriculture Australia and secretary of the Tasmanian Arboriculture Organisation, Colin is passionate about Urban Forestry and helping people realise the benefits of living with well managed trees.