Granny Flat Designs for Small Backyards (Under 450 sqm)

The State Environmental Planning Policy fast-track for granny flats only works on blocks 450 sqm or larger. But that does not mean smaller blocks cannot have a granny flat. Here are the design moves that work on smaller lots.

Option 1: Attached secondary dwelling

Build the granny flat connected to the main house, with a separate entry and no shared habitable rooms. Setbacks apply only to the external perimeter, not between the two dwellings. This saves significant footprint.

Typical layout: granny flat at the rear of the main house, accessed via a side path. Compact 50 to 60 sqm with bedroom, living, kitchen, bathroom.

Option 2: Detached over the garage

Some blocks support a granny flat above a garage at the rear. Two-storey form reduces footprint. Requires careful design for stair access and acoustic separation from the garage below. Council approval is usually required as DA rather than CDC because of the over-garage configuration.

Option 3: Compact detached

On a 400 sqm block with a smaller main house, a detached 50 sqm granny flat may fit within setback requirements. Setbacks: 3m rear, 0.9 to 1.5m sides typically. This leaves a usable space of around 6m x 10m for the granny flat.

Design strategies for small footprint

• Open plan living-dining-kitchen as one space.
• Compact bathroom (2.0 x 1.8m minimum).
• Built-in robes rather than walk-in.
• Sliding doors to save corridor space.
• Skylights for light.
• High ceiling (2700mm where possible) for spatial feel.
• Covered alfresco of 3 to 5 sqm.

Build cost

• 50 sqm detached: $130,000 to $170,000
• 60 sqm detached: $145,000 to $190,000
• 50 sqm attached: $115,000 to $150,000 (savings from shared services)