The Illawarra is a bit of a show-off. You’ve got the escarpment on one side, the ocean on the other, and a lake and a few creeks sitting in between. It’s gorgeous. It’s also exactly why your dream second storey or rear addition might need a few extra steps before anyone lifts a hammer.
Here’s the thing most people find out too late. Your block doesn’t have to be on a cliff edge or a riverbank to be caught by flood or bushfire rules. A quiet street in Woonona, a cul-de-sac backing onto bush in Figtree, a flat lot near Lake Illawarra: any of them can come with conditions attached.
I’m going to walk you through how the rules work, in everyday language, so you can plan your extension without nasty surprises. And fair warning, I’m not going to pretend it’s all simple. But it’s very manageable once you know what to look for.
First, Why Do These Rules Exist at All?
Short answer: because the Illawarra has a history. The escarpment funnels heavy rain down into creeks and low-lying suburbs fast. And the same bush that makes the area so pretty can burn.
The rules aren’t there to annoy you. They’re there so your new bedroom isn’t the first thing underwater, or the first thing to catch an ember. Think of them as the seatbelt of the building world. A bit fiddly, but you’ll be glad of it.
Which Council Looks After Your Block?
The Illawarra is covered by more than one council, and each has its own paperwork. In broad terms:
| Area | Council | Typical things to check |
| Wollongong, Thirroul, Corrimal, Dapto, Figtree | Wollongong City Council | Flood levels, flood planning level, BAL |
| Shellharbour, Albion Park, Oak Flats | Shellharbour City Council | Flood information, bushfire report |
| Kiama, Gerringong | Kiama Municipal Council | Flood and bushfire assessments |
I’d always start with your own council’s website or planning team. They know your street better than any blog post (including this one).
Flood Rules for Illawarra Extensions
Is my property flood-affected?
You can’t tell by looking out the window on a sunny day. The way to find out is to ask council. In Wollongong, for example, <you can apply for flood level information, or request a combined 10.7(2) and 10.7(5) planning certificate that shows whether your property is flood affected and the flood risk category where available. Council also suggests ringing first, because <it doesn’t hold flood level information for every property.
A planning certificate (people call it a 10.7 certificate) is basically a report card for your land. It lists the planning rules that apply to your lot, flooding included. It’s cheap compared with building the wrong thing.
The flood planning level (the big number)
This is the one to know. In Wollongong, <the minimum habitable floor level for most development needs to sit at the 1% AEP flood level plus 0.5 metres of freeboard, and that is called the flood planning level.
Let me translate that, because it sounds like a mouthful.
- 1% AEP flood means a flood with a 1 in 100 chance of happening in any given year. It doesn’t mean it only happens once a century. You can get two in a decade (bad luck, but it’s possible).
- Freeboard is a safety buffer on top. Think of it as the gap you leave at the top of a glass so it doesn’t spill when someone bumps the table.
- Habitable floor level is the floor of rooms you actually live in: bedrooms, lounge, kitchen, a new family room.
So if you’re adding a ground-floor living area, council may expect its floor to sit higher than your existing house. Sometimes that’s a step or two. Sometimes it’s a lot more.
Lake Illawarra is a special case
If you’re near the lake, take extra care. Wollongong council has applied a flood planning control to the Lake Illawarra floodplain, and its floor level requirement is based on <a predicted 2050 flood level that allows for climate-driven sea level rise. In one well-reported case at Windang, residents were told their floors might need to go very high, and some locals called it overkill. I’m not going to argue the rights and wrongs here. The point is: lake-side blocks can have tougher numbers than you’d guess, so check early.
Upper storey? Often the easier answer
Here’s a tip I give people a lot. If your ground floor can’t be raised easily, a second-storey addition can sometimes sidestep the worst of the flood floor issue, because the new living space sits well above the flood level. It isn’t automatic, and council still assesses it, but it’s worth putting on the table.
Complying development vs a development application
Many small extensions in NSW can go through a faster path called complying development, where a private certifier signs off if you meet set rules. Flood land makes this tricky. Wollongong has clashed with the state over how flood-prone land is handled under that fast-track system, and reporting at the time showed the state government told council its approach did not fit the statewide rules. Rules like this shift, so don’t rely on an old article (or on your neighbour’s memory from 2018). Ask council or your builder what path applies this year.
Bushfire Rules for Illawarra Extensions
Is my property on bushfire prone land?
Bushfire prone land is <an area on a bushfire prone land map that can support a bushfire or is likely to be subject to bushfire attack, and special construction standards and development restrictions apply there.
You’d be surprised how many suburban homes are on it. Backing onto the escarpment, a reserve, a patch of bush, even a big stand of trees nearby can pull you in. And a handy detail: the same source notes that <the map doesn’t show a property’s BAL rating, so being “on the map” is only step one.
What’s a BAL, and why do builders keep saying it?
BAL stands for Bushfire Attack Level. It’s a score that says how hard your house might be hit by a bushfire, and it decides how the house needs to be built. The NSW Rural Fire Service explains that <BALs have been used since 2009 as the basis for construction requirements that protect building elements from bushfire impacts.
Here’s the ladder, from calm to scary:
| BAL rating | Rough meaning | What it means for your extension |
| BAL-LOW | Very low risk | Few or no special bushfire construction rules |
| BAL-12.5 | Low risk | Basic ember protection |
| BAL-19 | Moderate | Stronger materials, ember-proof details |
| BAL-29 | High | Tougher windows, cladding, roofing and more |
| BAL-40 | Very high | Serious upgrades, bigger costs |
| BAL-FZ (Flame Zone) | Extreme | Direct flame contact possible; most demanding rules and often extra approval |
I’d summarise it this way: the higher the number, the pricier the build. A BAL-12.5 and a BAL-29 extension can be very different projects, even if the floor plans look identical.
How do I get my BAL?
You need an assessment. Wollongong council notes that <a Bush Fire Attack Level certificate can be issued by council or by a qualified consultant recognised by the NSW Rural Fire Service. Which route is best depends on how complicated your block is. Steep slopes and dense bush can make it a job for a consultant.
The main rulebook
If you ever want to impress your builder, drop this into conversation: Planning for Bush Fire Protection 2019, or PBP for short. It’s the RFS document that sets the standards for building on bushfire prone land. NSW law requires development on bushfire prone land to comply with it, and RFS describes it as <the development standards for designing and building on bush fire prone land. Your extension is also built to AS 3959, the Australian Standard for construction in bushfire-prone areas.
The very top end
If your land lands in BAL-40 or BAL-FZ, treat that as a flashing sign saying “talk to a professional early.” The planning circular on PBP 2019 flags those categories for special treatment, including in complying development. In plain terms: the fast-track option may not be open to you, and the approval path may be longer.
What If My Block Has Flood AND Bushfire Risk?
Oh, it happens. Picture a creek-side lot at the foot of the escarpment. Bush behind, creek in front, and a council planner somewhere saying “well, both.” (That’s a composite example, not a particular client, but I’d say it comes up more than you’d think in the Illawarra.)
The two sets of rules don’t cancel out, and sometimes they pull in opposite directions:
- Flood rules want your floor higher.
- Bushfire rules can make underfloor and subfloor areas more expensive to detail, because open space under a raised floor needs proper ember protection.
- Bushfire rules care about access and escape. Flood rules care about flood-free escape routes. Both are about getting people out safely.
This is why good design from day one saves heaps. An experienced builder and designer can often find one layout that satisfies both.
The Step-by-Step Checklist
Here’s the order I’d tackle things, from “just dreaming” to “ready to build”:
- Check the flood status of your lot with council (flood level information or a 10.7 planning certificate).
- Check the bushfire prone land map on the NSW RFS or council site.
- Get a BAL assessment if you’re on bushfire prone land.
- Ask which approval path applies: complying development or a DA.
- Talk to council early. Wollongong, for instance, offers <free development advice from a planning officer, which you can book as a call back on its website.
- Brief your designer on flood level and BAL before drawing anything.
- Get fixed costs that include the flood and bushfire requirements, not just the pretty bits.
What Does It Cost You?
I can’t give you a number for your project without seeing your block, and anyone who does is guessing. But here’s where the money usually moves:
| Factor | Why it can add cost |
| Raised floor level (flood) | More foundation work, extra steps, ramps or stairs |
| Flood-resistant materials | Better materials below the flood level |
| Higher BAL (bushfire) | Upgraded windows, doors, cladding, roofing, vents |
| Consultants and certificates | BAL report, flood report, survey |
| Longer approvals | Holding costs, rent, delays |
Spend a little up front. A few hundred dollars on the right reports can save thousands on a plan that has to be redrawn.
Common Mistakes I See (and How to Dodge Them)
- Designing first, checking later. Fall in love with a plan, then find the floor level is wrong. Painful.
- Assuming the neighbour’s approval applies to you. Two houses on the same street can have different flood levels or BALs.
- Trusting old information. Maps, flood studies and standards get updated.
- Building without approval. Council can make you remove unapproved work. Don’t risk it.
- Forgetting insurance. Tell your insurer about your extension. Flood and bushfire cover can depend on details.
FAQs
Do I need council approval for a home extension on flood-prone land in the Illawarra?
Usually yes, in the form of either a DA or a complying development certificate, if you meet the rules. Check your lot’s flood status first, because it decides the path.
What is the flood planning level in Wollongong?
For most development, the minimum habitable floor level is the 1% AEP flood level plus 0.5 metres of freeboard.
How do I find out if my house is in a bushfire zone?
Use the NSW RFS bushfire prone land map or your council’s map, then confirm with a Section 10.7 planning certificate. Remember that the map doesn’t tell you your BAL.
Who can give me a BAL certificate?
Council, or a consultant accredited with the NSW Rural Fire Service.
Can I build a second storey on a flood-affected block?
Often yes, and it can be a clever option. Council still assesses it, so confirm early.
Does a higher BAL rating mean I can’t extend?
Not necessarily. It means more demanding construction and, at BAL-40 or Flame Zone, a more complex approval path.
Do the rules differ between Wollongong, Shellharbour and Kiama?
Yes. State rules are shared, but each council has its own flood data, forms and local plans.
Wrapping It Up
Extending a home in the Illawarra is a bit like surfing here: gorgeous, rewarding, and best done with a good read of the conditions first. Check your flood status, find your BAL, talk to council early, and design with both in mind.
I’d rather you hear about these rules from me today than from a certifier halfway through your project. Not sure where your block sits? That’s the best time to ask.
Thinking about an extension? The team at Modern View Constructions Pty Ltd can help you work through flood and bushfire requirements before you commit to a design. Get in touch for a no-pressure chat about your block and your plans.