Building Near Trees? Read This First
If you're renovating, extending, or planning a new house, beware the tree regulations that could stand in your way
Rebecca Naughtin
5 November 2016
I have dedicated my career to advancing the education and practice of architecture. My experience demonstrates an understanding of the challenges facing the architectural profession, and I actively work towards realizing the standard between education and practice, and how this needs to be benchmarked locally and internationally.
Upon registering as a practicing Architect in Victoria in 2007, I formed Allen Naughtin Architects alongside Bruce Allen, and in 2012, shifted my focus to the residential sector and formed my current practice, Rebecca Naughtin Architect (RNA). RNA is an award-winning practice specialising in conception to completion delivery of projects, with inner urban briefs challenged by density, government policy and complex procurement.
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Trees can easily be overlooked during the design process, but they can become critical items later on. And don’t think you’re off the hook if you’re not planning to remove any trees to make way for your extension, renovation or new build. Building anywhere near a tree of significance (even if it’s not on your land) can bring with it regulations that might force you to change your design or limit your ability to build at all. It’s best to know where you stand with trees on or near your property early, before the design process gets underway – it will save you from headaches later.
Do your homework early
Before you get started on planning your new or renovated home, call up your local council and ask about their tree protection policies or ‘Tree Protection Local Laws’. This will inform you of all the different aspects of dealing with trees within or near your site. Sometimes these documents can be a little user unfriendly, however, so let’s have a look into some of the key elements.
Before you get started on planning your new or renovated home, call up your local council and ask about their tree protection policies or ‘Tree Protection Local Laws’. This will inform you of all the different aspects of dealing with trees within or near your site. Sometimes these documents can be a little user unfriendly, however, so let’s have a look into some of the key elements.
Name that tree
The first step is to identify what kinds of trees you have, especially those standing in the way of your proposed home or extension. This is typically required to be the botanical name of the tree, written in italics (Angophora costata, for example). There are many great books, apps and tree databases available that can help you identify trees. Hiring an arborist is a sure way to guarantee you’ve identified a tree in question by the correct name.
The first step is to identify what kinds of trees you have, especially those standing in the way of your proposed home or extension. This is typically required to be the botanical name of the tree, written in italics (Angophora costata, for example). There are many great books, apps and tree databases available that can help you identify trees. Hiring an arborist is a sure way to guarantee you’ve identified a tree in question by the correct name.
Assess its significance
Once you have identified the species of the tree, you then need to determine if the tree is a ‘significant’ or a ‘canopy’ tree. Different councils will have different requirements and definitions of what these entail, so it is best to check before making the assessment.
Significant trees can often be listed on a register available through the council. These trees have a top priority to be retained and having them on your property or on your neighbour’s can impact your design drastically if you are planning to build too close to them.
Once you have identified the species of the tree, you then need to determine if the tree is a ‘significant’ or a ‘canopy’ tree. Different councils will have different requirements and definitions of what these entail, so it is best to check before making the assessment.
Significant trees can often be listed on a register available through the council. These trees have a top priority to be retained and having them on your property or on your neighbour’s can impact your design drastically if you are planning to build too close to them.
Canopy trees can often be determined through measurements outlined by the council. The measurement of the trunk is typically taken from the DBH (diameter at breast height), which can be anywhere between 1.3 and 1.5 metres in height, depending on which council area you live in. You will then need to take the circumference you’ve gotten with the tape measure and convert it to a diameter. With this measurement you should be able to determine whether your tree is a canopy tree.
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The root of the issue
If your tree is determined to be either a ‘significant’ or ‘canopy’ tree and you are planning on building anywhere near it, you’d be better off to consult an arborist about your options for moving forward.
If your tree is determined to be either a ‘significant’ or ‘canopy’ tree and you are planning on building anywhere near it, you’d be better off to consult an arborist about your options for moving forward.
The arborist will determine the structural root zone, tree protection zone and crown drip line. They will then need to determine whether these will be accurate to your specific case. This is because these zones are determined through industry-standard formulas and can’t take into account conditions specific to your property.
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Some of the most important factors determining the assessment will be:
- What species is the tree?
- How does it react to various environmental conditions?
- Does it have far-spreading roots?
- Is it tolerant of heavy pruning?
- Does it react well to compaction or water logging?
- Are certain areas around the tree compacted, paved or impermeable?
- Are there water sources nearby that would have attracted the root system to an area not near your proposed building?
Inspect and measure
Once again, an arborist will need to determine the relevant conditions and tree species attributes and then prove them to the council, ensuring the tree will not be damaged or distressed by your proposal. One technique to determine exactly where the roots are is through ‘air spading’. This involves excavation of the soil through a specially designed air-pressured hose, helping to prevent damage to existing roots.
Your arborist will then document the extent and health of the roots and may even invite a council arborist to come and inspect the tree themselves. More traditional methods of excavation, such as using a spade, crowbar or trenching, can severely damage roots and cause damage to the tree.
Once again, an arborist will need to determine the relevant conditions and tree species attributes and then prove them to the council, ensuring the tree will not be damaged or distressed by your proposal. One technique to determine exactly where the roots are is through ‘air spading’. This involves excavation of the soil through a specially designed air-pressured hose, helping to prevent damage to existing roots.
Your arborist will then document the extent and health of the roots and may even invite a council arborist to come and inspect the tree themselves. More traditional methods of excavation, such as using a spade, crowbar or trenching, can severely damage roots and cause damage to the tree.
Infrared or thermal imaging technologies can also be used without damage to existing roots, though the accuracy of these can been questionable and the cost quite expensive. This is all dependent on which operator and equipment is used.
Live and let live
Finally, if it is determined that your proposal does fall within the tree protection zone, a tree protection plan will need to be established outlining how your design is going to minimise any disturbance to the subject tree. This could be though certain construction techniques, management of the site during construction, cantilevering structures, permeable surfaces and so on. A joint discussion with your arborist, architect and builder will determine the best outcome for your design.
Tree in your way? Don’t cut It down just yet
Finally, if it is determined that your proposal does fall within the tree protection zone, a tree protection plan will need to be established outlining how your design is going to minimise any disturbance to the subject tree. This could be though certain construction techniques, management of the site during construction, cantilevering structures, permeable surfaces and so on. A joint discussion with your arborist, architect and builder will determine the best outcome for your design.
Tree in your way? Don’t cut It down just yet
If you absolutely want to ensure that your tree is not damaged during the construction process, bonds can in fact be placed on trees and are in some cases required by councils. This is a way to ensure that no damage occurs to your trees. In all cases it is best to consult experts in the field when dealing with trees in or around your property to ensure you, your architect, arborist and builder all have the same intentions of retaining your trees and potentially incorporating them into the design process.
YOUR SAY
Have you a tree tale to share? Tell us about it in the Comments.
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YOUR SAY
Have you a tree tale to share? Tell us about it in the Comments.
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Read more renovation planning tips
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Good points unifini33 & trettrenta. Safety has to be the top priority.
If ever The Main Breadwinner and I get a divorce it will be because of a tree - he likes to plant and grow vegetables and wont be happy until he has trimmed and shaped my gorgeous old (and huge) spreading mulberry back until it looks like a poplar. "Its casting shade on me broad beans/kale/lettuce/asparagus ......" is the lament as I sprawl in its beautiful summer shade with a book and picnic.
We are planning to build on our large block. We have uncontrolled regrowth on the block that was completely cleared over 40 years ago. As a consequence we have a number of large trees that are reaching the end of their life. Our advice would be talk to a reputable arborist. We found one that also does contract work for our local council so they are very familiar with the rules. They advised that if possible to remove trees around the house and utilities and replant when building. Other clients have spent thousands trying to preserve trees only to have the tree die a couple of years after the build. The reason? Root damage plus changes to drainage which affect the trees viability. Even the movement of equipment under the trees (like workers parking their cars in the shade) can cause root damage and disease. It led to a great deal of heartache for the house owners and ended up being more expensive as the dead tree was difficult to remove as they had built around it.