What is a shadow diagram and when is it needed?

A shadow diagram shows how your proposed building will cast shadows at different times of day and year.

It helps council assess how your project affects sunlight access for neighbouring homes.

At Town Planning Sydney, we prepare accurate shadow diagrams as part of our full DA approval support.

Here’s what they include and when they are required under NSW planning rules.

1. Shadow diagrams show where and when shadows fall

These diagrams are drawn from a bird’s-eye view and show how much shadow your building will cast at different times.

Most councils require them at 9am, 12pm and 3pm on 21 June, which is the winter solstice. We make sure these times are clearly marked on each diagram.

2. Councils use them to assess sunlight access

Development application rules often require new buildings to preserve at least three hours of sunlight to neighbouring private open space or windows.

Shadow diagrams help councils check whether these rules are met. In Marrickville, we shifted a rear deck and roofline to reduce afternoon shadow on an adjoining yard.

3. They are often required for two-storey additions or dual occupancies

If you are adding a second storey, building close to the boundary or proposing a dual occupancy, you’ll likely need a shadow diagram.

We recommend including one early to avoid requests for more information later in the process.

4. Accuracy is critical, even small errors can trigger delays

Shadow diagrams must be drawn to scale, using correct building heights and sun angles.

Inaccurate or missing information is one of the most common reasons councils delay DA approval.

Our planning consultants review all diagrams to confirm they meet the local Development Control Plan.

5. Good diagrams show both existing and proposed conditions

Most councils want to compare existing shadows with proposed shadows. This helps show how much additional shadow your development will create.

We prepare ‘before and after’ versions to demonstrate minimal impact and strengthen your case.

6. Some councils require 3D or context-based shadow analysis

In dense or sloping areas, councils may ask for more detailed shadow modelling. This can include 3D diagrams, perspectives or elevation overlays.

We tailor each shadow diagram to your council’s exact requirements.

In Willoughby, our advanced diagrams helped secure council approval for a two-storey build on a narrow block.

7. Shadow diagrams support other DA documents

These diagrams must be consistent with elevation drawings, site plans and the Statement of Environmental Effects.

We ensure all documents match, so your development application stays on track without conflicting information.

With Town Planning Sydney, you get more than just drawings, you get complete planning advice to satisfy council expectations the first time.