Once the budget question is settled, timing is usually the next thing on your mind. You've decided a granny flat suits your block, and now you want to know when you'll actually be able to use it. There's no single answer to how long to build a granny flat, but most across Wollongong and the Illawarra take roughly six to twelve months from first sketch to handover. That's a wide range, and the gap between the quick end and the slow end comes down to a few things you can plan for.
Design and planning comes first
Before anyone pours concrete, there's a design stage, and it takes longer than people expect. This is where we measure the site, work out where the granny flat sits, and draw up plans that suit your block and how you want to use the space. Engineering, a site survey, and picking your inclusions all happen here too.
For a fairly standard build, design and documentation might take a few weeks. If you want a custom layout, or the block has its quirks, it can stretch to a couple of months. It's worth getting this part right. Changes are cheap on paper and expensive once the frame is up.
Approval: CDC or DA
Approval is the stage that swings your timeline the most, and it depends on which path your project takes.
In NSW, a granny flat is a secondary dwelling, and there's a 60 square metre floor area limit for many of the standard pathways. If your plans meet the rules, you may be able to go through complying development, or CDC. That's assessed by a private certifier rather than council, and it's generally the quicker route, often a matter of weeks.
If your block or design doesn't tick every box for CDC, you'll likely need a development application, or DA, lodged with council. A DA involves council assessment and sometimes public notification, so it usually takes longer, and the timeframe is harder to pin down.
Every block is different, so treat this as general guidance. Before you lock anything in, confirm the right pathway with your council or a certifier for your specific address. We handle the approval as part of the job, so you're not chasing paperwork on your own.
The construction stages
Once approval is in hand, the build itself tends to be the most predictable part. For a straightforward granny flat, construction often runs somewhere around three to five months. It moves through fairly set stages:
- Site prep and slab. Clearing, setting out, and pouring the slab or laying the footings.
- Frame. The walls and roof structure go up, and the shape of the place suddenly feels real.
- Lock-up. Roof, windows, and external doors go on, so the building is weathertight.
- Fit-out. Plumbing, electrical, insulation and plasterboard, then the kitchen, bathroom and internal doors.
- Finishes and handover. Painting, flooring, fixtures, a clean, and the final checks before you get the keys.
Each stage depends on the one before it, which is why a delay early on pushes everything back.
What adds to your granny flat build time
The timeline isn't fixed, and a handful of things reliably stretch it. Worth knowing before you start:
- A sloping block. Sites around the Illawarra and the Southern Highlands aren't always flat. Slope can mean extra excavation, retaining, or a suspended floor, and that adds time at the start.
- Custom design. A standard layout moves quickly. A one-off design with unusual rooflines or finishes takes longer to draw, approve and build.
- Weather. A wet stretch during the slab or frame stage can hold things up, and coastal weather doesn't always cooperate.
- Changes mid-build. Deciding to move a wall or swap finishes once work has started adds time, and usually cost.
- Service connections. Getting water, power and sewer connected can involve other parties and their timeframes, not just ours.
A realistic timeline for your block
Put it together and a typical granny flat lands around six to twelve months start to finish, with design and approval taking a good chunk of the early months and construction filling the back half. A simple design on a flat block that qualifies for CDC sits at the quicker end. A custom build on a sloping site going through a DA sits at the slower end. Treat those figures as a starting point, not a quote.
The best way to pin down a real timeline is to have your block and your plans looked at together. Once the site and the design are clear, the stages and dates firm up, and you can plan the rest of your year around them.
Want a hand with this at your place? Get a free quote or call 0434 037 851.