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February 4, 2020 Written by: Hew Gerrard

The importance of accurate shadow diagrams

On 29 June 2018 the Victorian Civil and Administrative Tribunal (VCAT) highlighted the methodology for determining compliance with Standard B21 under Clause 55.04-5 and overshadowing of open space objective in a Red Dot decision . This was not the first time that VCAT had raised the issue of shadow diagram accuracy and interpretation of Standard B21 , but it was the first time they had elevated it to Red Dot status.

In the eighteen months since, there have been at least six decisions made by VCAT which reference this Red Dot in discussing a proposal’s failure to include accurate shadow plans. All six decisions made were to refuse a planning permit. The importance of applicants ensuring they provide correct shadow plans (and for responsible authorities to confirm their accuracy) can therefore not be understated, particularly given overshadowing is also often one of the main concerns raised by neighbours.


In the most recent of these six decisions , the Tribunal Member commented it has become increasingly common for parties to get overshadowing assessments wrong . For what is a quantitative standard, this should not be the case.


Standard B21 is made up of two parts. The first of these reads:

Where sunlight to the secluded private open space of an existing dwelling is reduced, at least 75 per cent, or 40 square metres with minimum dimension of 3 metres, whichever is the lesser area, of the secluded private open space should receive a minimum of five hours of sunlight between 9 am and 3 pm on 22 September.

The second part to Standard B21 reads:

If existing sunlight to the secluded private open space of an existing dwelling is less than the requirements of this standard, the amount of sunlight should not be further reduced.

It is imperative therefore that the existing conditions are understood, as whilst software such as Trapeze or ShadowDraw makes calculating shadow lengths straightforward, they rely on the underlying base model being correct. Without this knowledge the ability to accurately determine the overshadowing impact from a proposed development is doomed to failure.

Through the preparation of an accurate survey plan and an accurate Neighbourhood Site Description Plan, planning permit applicants need to understand:

  • Where is the secluded private open space and how big is it?
  • What is the extent of existing overshadowing on this secluded private open space?

The accurate establishment of these two pieces of information will facilitate the production of accurate shadow diagrams and a far easier and more accurate assessment of compliance against the standard to be undertaken.


Whilst the Council planning permit process allows multiple opportunities to rectify and make amendments to plans, the VCAT process is usually less forgiving. It is important therefore that VCAT advocates for planning permit applicants have faith in the accuracy of the shadow diagrams provided. Recognising this, here at Glossop we will always carefully review shadow diagrams prior to amended plans being circulated to help ensure that shadow impacts are clearly identified and understandable.

For all VCAT Advocacy matters and to understand how Glossop can assist you with navigating the VCAT process, please contact Hew Gerrard on 9329 2288.

THROWING SHADE: Advanced shadow assessment 

When: 11 March 2020 9:30am-4:30pm

Where: Maddocks Offices, Docklands

If you want to really hone your own shadow assessment skills,  book a place in ADDO's new course ‘Throwing Shade’. It’s a full day, intensive course that will really put you ahead of the curve! The course is presented by John Glossop and Chris Goss of Orbit Solutions. 

Spots are limited to click here to register your place! You can view ADDO's full training calendar here.