Multigenerational Duplex: Family Close, Living Separate
Multigenerational living looks different from the version most people picture when they hear the phrase. It's not a single big house with grandparents in the back room. Across the Illawarra, more families are landing on a much smarter answer.
Two attached homes on one block, with separate front doors, separate kitchens, separate bathrooms, and shared land. The grandparents have their own home, the family has their own home, and nobody is living on top of anybody. It's the multigenerational duplex, and it's quietly becoming one of the most practical ways to keep three generations close in Wollongong, Shellharbour, and the South Coast.
Why Families in the Illawarra Are Choosing the Duplex Path
The pressure is straightforward. Adult kids in the Illawarra are staying local because they want their kids near grandparents, near the schools they grew up with, near the beach. Ageing parents are watching the cost of retirement villages, in-home care, and downsizer apartments and not loving any of the options.
The duplex answers both problems at once. The parents move into one half, the family moves into the other, and the block they already love stays in the family.
It works financially too. The parents sell their existing house, which in suburbs like Bulli, Thirroul, Woonona, or Corrimal typically sells for enough to fund their half of the new build with cash left over.
The family contributes their share, often by leveraging the existing block they brought to the project. The total mortgage load across both households is dramatically lower than either family trying to upgrade on thei
Designing a Duplex for Three Generations
A multigenerational duplex isn't just two identical houses stuck together. The two halves usually need to be designed deliberately differently, because they're for very different households at very different stages of life.
The grandparents' half wants to be single-level wherever possible, or at least have a bedroom, full bathroom, and laundry on the ground floor. We recommend a downstairs bedroom and an accessible bathroom for any multigenerational build, even if the parents are healthy and active when they move in.
Adding it later means a renovation. Building it in now means it's there if and when it's needed. Wider doorways, level thresholds, a walk-in shower instead of a shower over a bath, and good lighting cost very little extra at build stage and make the home age-proof.
The family's half can be more conventional. A double-storey layout with bedrooms upstairs, an open-plan kitchen and living downstairs, a study or rumpus for the kids. The brief is whatever the family normally wants in a custom home.
The shared block is where the design gets interesting. Where does each family park, and is the access separate or shared? Where's the outdoor space for each home, and how is it screened so each household has privacy when they want it and connection when they want it? Where do the kids play, and is that space accessible from both homes?
Whose washing line is whose? These aren't small questions, and they shape the design from day one.
Privacy, Access, and the Things That Actually Matter Day to Day
The single biggest reason multigenerational living goes wrong is privacy. Two households, even ones that love each other, need real separation to make daily life work. The duplex format solves most of that automatically. Each home has its own front door, its own walls, its own bathrooms, its own kitchen.
The grandparents can have a quiet night in without hearing the kids' bath time. The family can have friends over without the parents feeling they have to come and say hello.
The separating wall between the two homes needs to be done properly. Fire-rated and acoustic-rated construction is mandatory under the building code for duplexes, but there's a difference between the minimum standard and the standard you actually want when your parents live next door. We build separating walls that go well beyond what you'd hear in a standard duplex, because the families on either side are going to be living with that wall for decades.
Outdoor space is the other piece. Side-by-side duplexes give each home its own backyard, which generally works best for multigenerational families because the two outdoor areas can be totally independent. Front-and-back arrangements can work but need more careful access design so the rear home isn't
Why TAG Homes Is the Right Builder for a Multigenerational Duplex
TAG Homes has multiple duplex builds active across the Illawarra, in Woonona and Bulli, plus the recently completed and award winning Henrietta Street duplex in Towradgi. Multigenerational duplexes are an increasing share of the brief, and the design decisions that matter most for these projects, accessibility, acoustic separation, independent outdoor space, separate services, are decisions we've made before on real builds rather than worked through for the first time on yours.
TAG Homes is a construction-led builder with our drafting team. Bring your approved plans, or plans you're working on with your own architect or draftsperson, or start from a blank page through our design and construct pathway, and we'll take it from there. If your project calls for an architect, we can refer you to local architects we work with regularly who understand multigenerational design.
Ready to Talk Through a Multigenerational Build?
If your family is thinking about a duplex to keep parents close, give us a call. The fastest way to work out whether your block stacks up, how the design might work, and what the financial picture looks like across two households, is a quick phone conversation.
Call Grant on 0423 409 212. TAG Homes Pty Ltd, NSW Builder's Licence 369859C. Winner at the 2026 Master Builders NSW Southern Regions Excellence in Building Awards, and 2024 HIA NSW Region Start-up Business winner.
Questions we hear most
What's the best layout for a multigenerational duplex?
Generally, side-by-side, with the grandparents' half designed for single-level living and the family's half designed for whatever the family normally wants. The grandparents' half should include a ground-floor bedroom, accessible bathroom, and step-free access. The two halves share the block but have completely separate front doors, services, and outdoor space.
Can two families share ownership of one duplex?
Yes, and there are a few ways to structure it legally: some families own the duplex jointly under a single Torrens title, while others subdivide into two Torrens title dwellings and own one each. The right structure depends on tax, estate planning, and how the families want to handle a future sale. A conveyancer or solicitor familiar with multigenerational property is the right person to advise.
Do I need a special design for elderly parents to live in?
A few key features matter: a ground-floor bedroom, a step-free shower, wider doorways for any future mobility aids, lever-style door handles, and good lighting throughout. None of these add much cost at build stage, but all of them are expensive to retrofit later. We always recommend including them even if the parents are perfectly mobile when they move in.
Can one family member fund the whole multigenerational duplex build?
Yes, that's common. Often the older generation sells their existing home and funds the build, with the younger family contributing the block or buying their half progressively. Whatever the structure, a conveyancer and accountant should sit down with the family early to work out how ownership, contributions, and inheritance will work over the long term.compromised.r own.