Shadow diagrams for ACT granny flats.
Every ACT secondary residence DA requires a shadow diagram. It’s the single biggest source of neighbour objections AND the easiest thing to get wrong at design stage. Here’s how it works.
What a shadow diagram shows.
A shadow diagram is a plan-view drawing showing the shadows your proposed granny flat casts on neighbouring properties at three key times:
- 9:00 AM winter solstice (21 June): Shadow direction is east-south-east
- 12:00 noon winter solstice: Shadow falls due south
- 3:00 PM winter solstice: Shadow direction is west-south-west
The diagrams are drawn to scale, using the actual sun-angle for Canberra’s latitude (-35.28°) on those times. They are required because winter solar access is highly valued in ACT planning.
The rules the diagrams must show compliance with.
Under the ACT Residential Zone code, your granny flat’s shadows must NOT:
- Reduce solar access to any neighbouring north-facing living-area window such that less than 3 consecutive hours of winter sunlight (9am–3pm 21 June) reaches the window
- Cover more than 50% of any neighbouring private open space (POS) at 9am winter solstice (or noon, or 3pm)
- Cover more than 35% of any neighbouring solar panel array
Fail any of these and EPSDD will request design modifications or the neighbour will object.
Design strategies to pass shadow compliance.
- Place the granny flat behind the main dwelling (south side of block). Shadows fall onto the existing dwelling’s shadow, not extending to neighbours.
- Single-storey, low ridge height (4.0m max). Shorter shadow. Eaves at 2.4m to floor.
- Step the design back from boundaries. A 1m extra setback reduces shadow extent at boundary by ~1.5m on south boundary, ~0.8m on east/west.
- Skillion roof sloping south. Reduces ridge height and overall shadow length compared to gable roof.
- Open-plan / no second storey on south side. Allows existing dwelling to remain south of granny flat without overshadowing.
What gets challenged.
Neighbour objections we’ve seen in 2025:
- Overshadowing a vegetable garden in winter. Genuine objection if neighbour relies on solar access. Resolution: reduce ridge height, reduce setback, or move granny flat 2–3m further from boundary.
- Overshadowing a clothesline area. Less compelling objection but still valid. Resolution as above.
- Overshadowing a swimming pool. Genuine objection if the pool is used in winter. Most ACT pools aren’t.
- Overshadowing solar panels. Mathematical — if the diagram shows <35% panel coverage, objection fails. If >35%, design must be adjusted.
- Privacy from upper-level windows. Not shadow per se, but often raised at the same time. Resolution: high-set windows or obscure glazing on south-facing facades.
How we handle it.
- Shadow diagram prepared by ANU-affiliated architectural drafter to ACT standard
- Pre-DA discussion with neighbour, sharing the shadow analysis upfront
- Design tweaks (ridge height, setback) if objection is anticipated
- Cost: $720 shadow diagram, included in our quote
- If a neighbour objects formally, we work with EPSDD planning officer to mediate — usually a small design tweak resolves it
Where we work.
Free preliminary shadow analysis.
We’ll model the proposed build against your block and tell you straight what’s achievable.