How Close to a Tree Can You Install Footings? A Melbourne Builder's Guide

Short answer: in Melbourne and across Victoria, footings should generally sit outside the Tree Protection Zone (TPZ), which is a circle around the trunk with a radius of 12 times the trunk diameter measured at 1.4 m above the ground. For most established suburban gums and oaks, that works out to a 4 m to 10 m exclusion zone. If you can't avoid the TPZ, your options are limited to non-excavated footings (screw piles or driven steel stumps) and, for council-protected trees, an arborist-supervised design.

That's the rule of thumb. The honest answer is more nuanced. It depends on the tree species, whether the tree is council-protected, the soil class on your block, and the kind of footing you're proposing. This guide breaks down each of those factors so you can plan a deck, extension, pergola or restump near a tree without ripping out roots, killing the tree, or copping a council fine.

Why the Distance to a Tree Matters

The temptation on a tight Melbourne block is to push the deck or extension as close to the tree as the design allows. Before you commit to a footing layout, it's worth understanding what's actually going on under the lawn.

A mature tree's structural roots (the woody anchor roots that hold it upright in a windstorm) typically extend out to at least the edge of the canopy, and often well beyond. The fine feeder roots that draw water and nutrients can extend two to three times further again. Cutting either type causes problems:

• Tree decline or death. Severing more than around 10-15% of a tree's root plate can destabilise it or kill it within 1-3 seasons. The damage often shows up after the build is finished, when the warranty conversation gets awkward.
• Wind-throw risk. A tree with one side of its anchor roots cut is far more likely to fall in a Melbourne summer storm, straight onto the structure you just built.
• Council penalties. Most Victorian councils protect significant trees through local laws and planning overlays. Damaging or removing a protected tree without a permit can attract fines from a few thousand dollars up to tens of thousands per tree, plus replacement orders.
• Footing movement. Reactive clay soils across Melbourne's west, north and inner suburbs swell and shrink with moisture. Roots dry the clay; cutting them changes that moisture profile and can cause differential settlement in nearby footings, even years after the build.
• Pipe and paving damage. Surviving roots redirect themselves around new obstacles and head for the easiest moisture source, often your stormwater, sewer or the underside of the slab.

In other words, "how close can I get?" is really four questions stacked together: what won't kill the tree, what won't get me fined, what won't move under the building, and what's actually buildable on this site.

How to Calculate the Tree Protection Zone (TPZ)

The Tree Protection Zone is the industry-standard exclusion radius used by Victorian councils, arborists and structural engineers. It comes from AS 4970-2009: Protection of trees on development sites, which most Melbourne councils either reference directly or mirror in their local laws.

So a tree with a trunk diameter of 0.4 m at chest height has a TPZ of 4.8 m radius, which works out to a roughly 9.6 m diameter no-go circle measured from the centre of the trunk. Within that circle, AS 4970 expects:

• No excavation, no soil compaction, no stockpiling materials.
• No more than 10% of the TPZ area can be encroached without an arborist's specific approval.
• Where the TPZ is unavoidably entered, footings should be non-destructive: typically screw piles, hand-augered piers or pin piles installed without trenching.

There's also a tighter inner circle called the Structural Root Zone (SRZ), which is the absolute minimum needed to keep the tree standing up. The SRZ is calculated from a different formula based on trunk diameter at ground level, and is non-negotiable. No footings, no exceptions, no matter how the design is rated.

For most suburban projects, getting an arborist to mark the TPZ and SRZ on a site plan before the engineer designs the footings is the cheapest insurance you can buy. It's a couple of hours of fieldwork that prevents a redesign mid-build.

Worked Examples: Common Melbourne Trees

To make the formula concrete, here's how the TPZ plays out for trees you'll typically encounter on a Melbourne block:

A few Melbourne-specific notes on these numbers:

• In the inner suburbs (Carlton, Fitzroy, Hawthorn, Camberwell, Malvern), elms, plane trees and oaks dominate. These trees have large DBH, large TPZs, and are almost always covered by council Significant Tree registers.
• In the eastern and outer-eastern suburbs (Knox, Maroondah, Yarra Ranges), eucalypts on bushland blocks are usually protected under planning scheme overlays such as the Vegetation Protection Overlay (VPO) or Significant Landscape Overlay (SLO).
• In the western and northern growth corridors (Wyndham, Melton, Hume, Whittlesea), street trees and reserve trees nominally outside your boundary still have TPZs that can extend onto your property, and their roots are absolutely on your block.

Why Concrete Footings Are a Problem Near Trees

Concrete is the default in Australian residential construction, but it's the worst footing choice when there's a significant tree on site. Three reasons:

1. The hole is bigger than the footing. A 450 mm diameter bored pier needs a hole at least that wide and typically 1.2-1.8 m deep. To get the auger in you also need a swept turning circle, plus space for the spoil. Inside a TPZ that level of disturbance simply isn't allowed under AS 4970.
2. Roots get cut, not pushed. An auger or a shovel doesn't negotiate around a 60 mm structural root, it shears straight through it. Each cut is an entry point for fungal pathogens like Armillaria (honey fungus), which is endemic in older Melbourne gardens.
3. Wet concrete is alkaline and exothermic. Fresh concrete sits at pH 12+ and gives off heat as it cures. Any feeder roots in direct contact with it during the pour are killed. Over the long term, the high-pH leachate continues to alter the soil chemistry around the footing, bad news for established trees that have spent decades fine-tuning their root zone.

Layer on the practical issues (the concrete truck can't reverse over the dripline, you can't trench services through the TPZ, the spoil has nowhere to go on a tight block) and concrete footings near a mature tree become an expensive, slow, risky proposition. Quite often, the tree is the reason a project gets value-engineered away from concrete in the first place.

How Concrete-Free Footings Let You Build Closer to Trees

Concrete-free footing systems (screw piles and driven steel stumps) change the conversation because they're installed by displacement rather than excavation. Instead of removing a column of soil and replacing it with concrete, they push the soil aside and lock into the surrounding ground.

This is why arborists and councils across Victoria increasingly accept these systems inside (or partly inside) the TPZ where a concrete pier would be refused:

• No excavation. No trench, no spoil, no compaction zone for plant equipment.
• Roots are deflected, not severed. A 76 mm or 89 mm steel shaft will glance off woody structural roots, and small feeder roots simply re-route. If the installer hits a serious root, the pile can be repositioned 100-200 mm and re-piloted.
• Tiny footprint. Most installs are done with a compact drive head on a mini-excavator or hand-piloted with a portable hydraulic motor, both of which fit through a 900 mm side gate.
• No alkaline leachate. Steel doesn't change the soil chemistry around the tree.
• Reversible. If the design changes, a screw pile can be unwound and reinstalled in a new position, a concrete pier can't.

At Easy Footings we install three concrete-free systems from BMSA Footing Solutions, each suited to different proximity scenarios:

• SurePile is a full helical screw pile. It's the first choice when you're inside or near the TPZ of a significant tree, because they reach competent bearing strata below the active root zone and can be load-tested in place.
• RapidStump is a driven steel stump for decks, pergolas, granny flats and similar light-to-medium loads. Quick to deflect around small roots; ideal on suburban blocks where access is tight.
• StumpRite is an adjustable steel stump system suited to restumping and relevelling existing homes near established trees, where the footprint is fixed and you have to work between the root flares.

For a side-by-side breakdown of which system suits which job, see our RapidStump vs StumpRite vs SurePile comparison.

Council Rules & Protected Trees in Victoria

Before you finalise a footing layout, you need to know whether the tree is protected. In Victoria there are three layers of protection that can apply, sometimes simultaneously:

• Local Significant Tree Register. Most Melbourne councils, including Boroondara, Stonnington, Bayside, Glen Eira and Yarra, maintain registers of individually listed trees. Works inside the TPZ of a registered tree typically need a tree permit and an arborist report.
• Planning scheme overlays. The Vegetation Protection Overlay (VPO), Significant Landscape Overlay (SLO) and Environmental Significance Overlay (ESO) apply across whole streets or precincts. If your title is covered, removing or lopping vegetation above a certain size needs a planning permit, and footing works inside a TPZ often trigger the same trigger.
• Federal & state-listed species. Indigenous species such as river red gums (Eucalyptus camaldulensis) on land in Melbourne's west and north can be additionally protected under the Planning and Environment Act and, in some cases, the EPBC Act.

The practical workflow most Melbourne builders follow is:

1. Check the property report and the council's online planning maps for overlays.
2. Check whether any tree on or adjoining the site is on a Significant Tree Register.
3. If yes to either, engage an AQF Level 5 consulting arborist to produce an Arboricultural Impact Assessment (AIA) before lodging the building permit application.
4. Have the structural engineer design footings to the AIA's recommendations, almost always non-excavated screw piles or driven stumps inside any TPZ encroachment.

Skipping these steps and digging a concrete pier inside a protected tree's TPZ is one of the fastest ways to convert a profitable job into a five-figure council infringement. It happens every year in Melbourne, and the fines have been climbing.

Practical Placement Tips for Builders

Once you know the TPZ and you've chosen a non-excavated footing system, there are still smart and not-so-smart ways to lay out the piles. A few rules of thumb we use on Melbourne and Victorian sites:

• Cantilever where you can. Pulling the line of footings 300-600 mm further from the trunk and cantilevering the bearer back over the TPZ edge is almost free, and dramatically reduces root impact. Most timber bearer details handle a sensible cantilever without an upgrade.
• Pilot before you pile. On any pile inside the TPZ, drive a small-diameter pilot rod first. If it stalls on a structural root, move the mark by 100-200 mm and try again. We treat the engineering setout as a target, not a survey peg.
• Reduce the pile count. Going from a 1.5 m pile spacing to 2.4 m using a deeper bearer means fewer root crossings, almost always worth the tiny added cost in steel.
• Avoid the radial strip. Roots radiate from the trunk like spokes. A line of footings perpendicular to the trunk crosses fewer of them than one running tangentially around the dripline.
• Plan the access path. Compaction kills as many trees as cutting does. Ground-protection mats over the access route inside the TPZ are usually a condition of the arborist sign-off, and they're worth using even when they're not.
• Watch the surface levels. Adding or removing more than 100 mm of soil over the root zone changes oxygen and moisture profiles. If your design needs a step or a retaining edge near the tree, work it out before piling, not after.
• Drainage matters too. Don't redirect roof or surface water onto, or away from, an established tree. Either change kills it slowly. Easy to forget when you're focused on the footings.

When to Engage an Arborist or Engineer

You don't need a full arboricultural team for every backyard project. As a working guide:

• Small ornamental tree, no overlay, footings outside the TPZ. Builder + structural engineer is enough. Standard concrete-free footing design.
• Established tree, footings outside the TPZ but the access is inside it. Get an arborist's written sign-off on the access route and ground protection. A short letter, not a full report.
• Any encroachment into the TPZ, or a council-listed tree, or an overlay on title. Engage an AQF Level 5 consulting arborist for an Arboricultural Impact Assessment. The structural engineer designs to the AIA's recommendations, and the building surveyor will require both documents.
• Encroachment into the SRZ. Stop. Redesign. The SRZ is not a negotiable boundary; even with permits, footings inside it are very hard to justify and almost certainly destabilise the tree.

A consulting arborist's report typically costs less than the cost of redesigning a footing layout mid-build, and a fraction of the cost of replacing a damaged street tree under a council infringement notice. Engage them before the engineer drafts the footing plan, not after.

Frequently Asked Questions

The Bottom Line

You can build close to a tree in Melbourne, much closer than most builders assume, as long as you swap the default concrete pier for a non-excavated, concrete-free footing and you respect the Tree Protection Zone defined in AS 4970. Get the arborist on board early, design the footings around the roots rather than the other way around, and use the right BMSA system for the load you're carrying. The tree stays standing, the council stays happy, and the build runs on time.