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Why the builder belongs at the first sketch.
Builder's perspective · Dual occupancy · Illawarra
Two generations, one block: what I ask families before we design a dual occupancy
When a family builds two homes on one lot for parents and children, the hardest questions are not about the building. These are the six I ask first, because the answers change the design.
Why ask families questions before designing?
Because two generations on one lot is a living arrangement first and a building second. The answers decide whether the right building is a granny flat, a dual key home, or a full dual occupancy, and each leads to a different design, approval and title.
What are the six questions?
- Who lives where, now and in ten years? A parent who is independent today may need a step-free home later.
- Will either home ever be sold or rented separately? If yes, only a dual occupancy keeps that open. A lot with a granny flat approved under the Housing SEPP cannot be subdivided.
- How separate should the homes feel? Separate entries, outdoor spaces and parking matter more day to day than floor area.
- Who pays for what? Separate meters for water and power make sharing costs simple and keep the option to subdivide.
- How much space does each household need? A granny flat is capped at 60 m² under the state rules (in Wollongong, the greater of 60 m² or 67% of the main house). A dual occupancy gives two full-size homes.
- What does the block allow? Zone, size, width and fall decide which of the options above is even possible.
How do the answers map to the options?
| If the family says | The option is usually |
|---|---|
| One property, never sold separately, small second home | Granny flat |
| One building, two front doors, one title | Dual key home |
| Two full homes, may sell one later | Attached or detached dual occupancy |
The planning side of each option is set out on dual living and multigenerational homes.
What is the next step?
Answer the six questions as a family, then have the block checked before anyone draws a plan (my site assessment page explains what that visit covers). This is how we build dual occupancy homes for Illawarra families, from the block check to handover.
Related reading
Fixed price or cost plus?
Which building contract I would sign, and why.
Sources
- NSW Planning, Secondary dwellings: the 60 m² limit and the no-subdivision rule.
- NSW Legislation, Wollongong Local Environmental Plan 2009: clause 5.4 secondary dwelling size.
- Dual Occupancy, Dual key homes in NSW: how a dual key can be approved.
General information from a builder, not planning, legal or financial advice. Confirm the controls for your lot with your council or certifier.
Questions
Keiron Moore on dual occupancy for families
What should a family decide before building a dual occupancy?
Keiron Moore asks six questions: who lives where now and later, whether either home may be sold, how separate the homes should feel, who pays for what, how much space each household needs, and what the block allows.
Is a granny flat or a dual occupancy better for parents?
Keiron Moore says a granny flat suits a small second home that will never be sold separately, while a dual occupancy gives two full-size homes and keeps the option of separate titles.
Can a granny flat for parents be sold later?
No. Keiron Moore notes that a lot with a granny flat approved under the Housing SEPP cannot be subdivided, so it stays with the main house.
How big can a granny flat be in Wollongong?
Keiron Moore explains the limit is 60 square metres under the state rules, and in Wollongong the greater of 60 square metres or 67 per cent of the main dwelling's floor area.