Design WA – How to retain existing trees on development lots


Existing trees and their precious canopies are being cut down across Perth development sites at an alarming rate. Street and park trees in the public realm are comparatively easy to protect, but how can we protect trees on private lots in order to secure their well-documented benefits for future generations? And equally, how do we provide certainty to developers and not onerously increase development costs? This is a real challenge.

Damien Pericles (Founding Director at REALMstudios) has been working with Western Australia’s Department of Planning on the recently released Apartment Design Policy which will replace (in part) existing R-Codes. The policy is part of Design WA (formerly the ‘Planning Reform for Better Design’ project).

One of the key chapters of the policy is titled ‘Existing Tree Retention’ and is put forward as an important and early site planning consideration. Together with other related chapters (like Deep Soil Zones) this chapter aims to raise awareness and shift community and developer values. Tree retention involves careful analysis, planning, due diligence and resolution of technical issues. Four key innovations come through in the policy:

Five Year Rule

The first innovative approach is what defines an existing tree and the ‘five year rule’. “Existing trees” includes those physically on-site and those that have been removed but are clearly identified on an aerial photo within the last 5 years. This aims to address clearing by owners/developers long before lodging of a development application.

Deep Soil Zone Incentive
The second innovative approach utilises a built-in incentive relating to Deep Soil Zones. In a related chapter Deep Soil Zones set objectives and minimum guidelines for provision of soil area not covered by building or structure and that supports healthy plant and tree growth. The incentive allows a variation of 12% Deep Soil Zone down to 8% when existing trees are retained.

Tree Replacement Offset
The third innovative approach uses an offset mechanism. Where a tree is unable to be retained, then a cost is to be paid for the planting of 4 additional trees per tree not retained within the immediate project vicinity (but outside the development site). The cost per tree of supply, installation, irrigation and maintenance for 2 years of a 100Lt native tree is to be determined by and paid to the local authority.

Minimum landscape areas
The fourth initiative applies in high density areas where built form maximizes all or most of the site area and deep soil zones cannot be achieved. In this instance a minimum of 25% site area is to be planting on structure.

These and other initiatives in the Apartment Design Policy will set new standards of practice and improve the amenity and liveability for residents living in apartments.

Further information of the full draft suite of documents can be found at Design WA.

Apartment Design Policy Cover

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Last chance to have your say on the K2K Urban Design Competition coincides with Realm Studios Sydney studio launch

REALMstudios has launched its new shared studio space in Surry Hills Sydney, home to our growing NSW team and city making and liveability project base.

This month we will be celebrating the launch of the shared studio space by opening it up to friends of the practice and Damien giving a preview presentation of our CODA team’s K2K Competition Entry……see link for a sneak preview.

We invite you to this event which will be accompanied with drinks and canapés, and if you would like to be part of this then please email Tamara at We would be delighted to see you there.

The launch marks another milestone for REALMstudios having; a growing portfolio of work across the research, public and private sectors, policy and design guidance, and a growing and passionate team who are dedicated to the idea of better places and better cities through design. Our new Sydney studio represents that growth.

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