Why New Homes Still Flood in Australia

1. Introduction – Still Mopping Up?

On a muggy afternoon in Wauchope, SES volunteer Dusty helped carry soaked carpet out of a brand-new four-bedder. It was built on compacted fill and passed certification, and it still flooded.

"I have been a member of the SES for 30 plus years going to thousands of call outs during bad weather and heavy rain. Most jobs calling for sand bags to stop water running into houses.

There is no hope to prevent the water running inside. the damage bill is millions every time, and lets not look at some of the roof flashings they're a joke. The amount of new subdivisions that are dug into the side of hills or in very low areas are creating water run off directly into homes needs to stop."

“We’ve never seen new houses flood like this,” he later said.

"People just assumed the slab was high enough… until water cascaded through the garage into the living room.”

That scene isn't isolated. Across regional NSW, Queensland and Victoria, homeowners and insurers are asking the same question: why are new homes still flooding in modest events?

The 2022 floods led to large buyback programs (for example around Lismore), and in 2024–25 the average insurance payout for internal water damage claims was reported at A$30,361, up 72% since 2014.

The Insurance Council of Australia has since pushed for changes to building rules to better protect homes in flood-prone areas.

Meanwhile, schemes like the NSW Northern Rivers Resilient Homes Program have bought and demolished or relocated hundreds of homes, many of them technically compliant with the NCC and state codes. That leaves residents and councils asking whether the rules really get it right.

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Code compliance isn’t resilience. Even when new slabs meet minimum code, paper‑based certification systems and lenient oversight leave homes vulnerable to floodwater.

Major insurance losses, buyback programs such as NSW’s $880 million Resilient Homes Program, and the Insurance Council’s push to embed resilience in the NCC all underscore that doing just enough under the Code no longer protects Australian homeowners from flood risk

2. Minimum Slab Heights — Myths, Codes & What’s Currently Required 📏

Here's what you need to know:

What the codes currently require:

National Construction Code (ABCB Housing Provisions): Under the Deemed-to-Satisfy provisions in Housing Provisions 3.3.3(b) (NCC 2022), the slab must be at least:

100 mm above finished ground level in low‑rainfall or sandy, well‑drained sites,
50 mm above impermeable (paved or concreted) surfaces that slope away from the house, or
150 mm above any other ground condition

There is no requirement anywhere in the NCC or the Queensland Development Code (QDC) for a slab to be 250 mm above natural ground level (NGL). That 250 mm figure was a good builder rule of thumb for many years, and rightly so, but it isn't part of any standard.

Why “100 mm” isn’t enough when flood overlays come into play

Where a property lies in a listed flood hazard area, the Queensland Development Code MP 3.5, together with state flood overlay mapping, applies.

It sets the Finished Floor Level (FFL) at no less than the Defined Flood Level plus 300 mm freeboard by default, i.e. the floor should be at least 300 mm above the 1% AEP flood level (the flood with a 1% chance of happening in any year) unless council sets a different figure.

That requirement doesn't rely on NGL at all, and it's legally enforceable in Queensland. Builders must set slab levels (RLs, or reduced levels) using AHD, the Australian Height Datum. Sticking to the NCC minimum of 100 mm doesn't cut it in flood areas.

QDC MP3.5

View below or click HERE to view and download (opens Docsend).

What used to happen, and why that no longer delivers

Many homes constructed before the 2010–11 floods (especially in coastal floodplains) were built with slab levels of 250–300 mm above NGL, not because the code demanded it, but because it was safer based on experience.

👉️ Over time, slab levels have crept down as cost pressure and volume building squeezed margins. Value-engineering has to happen somewhere, and it's easy to trim the 'rare event' costs to make the price easier to swallow.

That old-school freeboard gave us a buffer, but without a flood-level plan the slab height often failed anyway.

Also beware: Slab surveys only record the reduced level (RL) immediately after pouring. But as soon as retaining walls are built, paving is laid, or landscaping takes place, the surrounding ground level can rise—eating away at the freeboard you thought you had.

That’s why it’s important not just to set slab height above ground, but also to actively consider how water flows to, across, and away from the site—not just how high the slab sits.

✅ What you should do:

Always show slab RLs in AHD on all plans, not “X mm above NGL” or driveway level.
Make sure an AHD reference point is marked on site so trades can set heights from it.
If in a flood overlay, the slab must meet QDC MP 3.5’s 300 mm freeboard above declared flood level.
Even outside overlays, the NCC's 50–150 mm rule is binding, but it's wise to exceed it near waterways or where site drainage is uncertain.
👉️ Allow for a buffer. Passing compliance and performing in reality are two different things. Talk to people who've lived in the area for years, ask what's happened in the past, and factor that into your plans.
- Sure, you might save money by meeting only the current performance standard, but will you really be saving when a foot of water is flowing through your property?
- It’s not like your house didn’t cost a packet to begin with — so think about how you apportion value and return on investment when budgeting for your new build. In the end, it’s a risk assessment — a balancing act between probabilities and consequences.

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✅ What you should do:
The NCC requires only 100–150 mm above ground, and QDC MP 3.5 mandates 300 mm above flood levels in flood hazard zones.
Always specify slab levels in Australian Height Datum (AHD) and design for flood‑resilient freeboard.

3. From Council Inspectors to Private Certifiers — What’s Missing Now? 🕵️

Since the late 1990s, NSW, Queensland and other states have moved away from council inspections at key build stages toward private certifiers appointed by the builder.

Before that, councils routinely inspected at slab, frame and final stages, which gave an independent second pair of eyes on things like drainage fall, fill compaction and slab height.

✅ How it works now — and where it falls short

In Queensland, private certifiers are licensed by the QBCC under the Building Act 1975. NSW has its own scheme under the Building and Development Certifiers Act 2018. Queensland's Building Regulation 2021 does require stage inspections for a new house (excavation, footings or slab before the pour, frame, and final), although some stages can be inspected by a 'competent person' on the certifier's behalf. What those inspections don't do is check your drainage design or site falls in any detail.

However:

Most developers nominate and employ certifiers, who are paid by the builders—not the landowners or councils.
Beyond the mandatory stages, there's no guarantee of extra site visits unless someone pays for them, and a stage inspection is a snapshot, not supervision.
Oversight of certifier performance is limited, with infrequent audits by regulators, and little or no public disclosure of adverse outcomes.

The result? Many homes tick every box on paper but perform poorly in real conditions, especially on filled sites, sites with too little fall, or flood-exposed lots.

Principal 1 (from the embed doc above)

The ABCB’s 2021 Discussion Paper (p. 30) states: “The owner should appoint the private building certifier and have a direct contractual relationship with the building surveyor for the performance of their services.”

As the saying goes, he who has the gold makes the rules. When certifiers are appointed and paid by builders, their financial interest lies with the builder, not with the home or the people who'll live in it.

👉️* This conflict of interest has to end. Having the owner appoint the certifier is a simple reform that fixes a problem that should never have existed.*

🔍 What the Shergold–Weir “Building Confidence” report found

Commissioned in 2017 by the Building Ministers’ Forum and released in 2018, the Shergold–Weir report flagged serious systemic failures in the certification regime:

A widespread lack of independence between builders and certifiers creates conflicts of interest (Recommendations 9–11).
Certifiers are often held in the same design‑and‑construct environment as builders, leading to "novated" relationships where the architect or certifier ends up working for the developer/builder—not the owner.
Mandatory inspections at notification stages (e.g., slab) are not enforced uniformly across jurisdictions (Recommendation 18), diminishing the ability to catch critical errors early.
Documentation is often poor or incomplete, and many performance solutions have never been robustly reviewed or audited in practice.

👉️ Less than half of the 24 recommendations had been fully implemented by mid-2021; audit and enforcement powers remain weak in many states.

✅ Practical consequences we see today

Slab RLs set on the wrong datum or at sketchy elevations, and no inspector checks the actual fall or stormwater path on-site.
Drainage planning after pour goes undocumented—post‑concrete fills often create water “bowls” around the slab.
Certification can be virtually invisible to the homeowner, yet their insurer must step in when things fail.

👉 *We’ve covered certifiers and compliance in more detail i*n this post

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Council inspections offered real scrutiny; private certifiers offer compliance facilitation. Certificate holders are paid by builders/developers, auditing is sporadic, and on‑site inspections are often minimal unless you pay for extras—meaning potential flaws in slab height, drainage and site fall commonly slip through. We've articulated our position on mandatory LGA inspections in THIS POST

4. LHA Building Standards: Designed for Support, Built to Fail Rain Events🏚️

These homes are a good example of inclusive design. LHA (Livable Housing Australia) standards and NDIS Specialist Disability Accommodation (SDA) homes, especially High Physical Support (HPS) homes, are designed for people with complex mobility needs.

Features like zero-threshold entries, step-free showers, wider doorways and gentle ramps are part of the spec. That's the good news.

But meeting accessibility requirements can create flood risk when drainage planning is skipped, poorly done, or not thought through for the site.

Here’s where the flaw emerges:

🧩 The problem: Accessibility rules override basic waterproofing principles

The SDA Design Standard for HPS homes requires a flush threshold at the main entry, meaning no step or lip. To get a compliant gentle fall to that door, the outdoor entry pad (porch or landing) may need to extend more than 1800 mm from the doorway.

That’s not the issue. The issue is what happens when builders take advantage of a code loophole:

If the porch is more than 1800 mm deep, there is no requirement to provide a grated drain or trench drain at the door.

In other words, a wide slab of concrete can slope gently toward the doorway with no drainage provisions, and it’s still compliant. When heavy rain hits, that wide apron funnels water toward the entry door with no strip drain, no fall away, no trench to redirect runoff.

🛠️ The fix is easy — but no one’s enforcing it

This issue is entirely avoidable:

A strip drain or grated trench should be installed at every flush-threshold entry, regardless of porch depth.
Even better: add a secondary overflow path that drains away from the building. In big storms, primary drains get overwhelmed or blocked, and if the water has nowhere to go it backs up against the house and finds its way in (under doors, through weepholes, frames and cracks).
Certifiers and designers must treat drainage and water management as part of access design, not a competing priority.

These solutions add only a few hundred dollars to the build but prevent thousands in damage and disruption.

see further reading section below for additional posts on this topic

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A design can be 100% compliant and still 100% flood-prone.
SDA homes often feature wide, step-free entries—but unless drains are installed, or sufficient grading from the dwelling has been done, water has nowhere to go but inside. Compliance rules aren’t enough. Good practice demands more - not just ticking a box.

5. Subdivisions on Hills and Floodplains — A Planning Problem 🌧️🏞️

Flooded homes aren’t always the result of poor individual design. Sometimes, the problem is baked in—right from the subdivision layout stage.

Over the past two decades, estates have been carved into former farmland, floodplains and steep hillsides. Under pressure to release land quickly, many councils have rezoned marginal land without fully considering drainage or long-term water flow paths.

🧱 Cut-and-Fill Plateaus: Great for Build Speed, Terrible for Water

Modern subdivisions often rely on mass earthworks to create flat, buildable lots. The standard approach:

Cut into the slope at the rear, fill at the front.
Build retaining walls to hold soil at lot boundaries.
Construct flat pads just wide enough for a slab and side path.
- failure to add diversion drains at batter toes
- failure to meet basic subsidence policy requirements
Run roads and footpaths on elevated crowns between lots.
No consideration of overland flow between properties. If your lot is the lowest in the street and surrounded by filled land, you're often stuck with the consequences. Councils have limited power to step in, and the fix is usually civil action.

While this works on paper, the outcome is often a series of shallow “bowls” where water accumulates:

The slab may be flat, but surrounding surfaces can trap water.
Footpaths built higher than lots can direct runoff toward houses.
Crossfalls toward neighbouring fences (instead of streets or drains) create private flood channels—often unnoticed until heavy rain.

🏞️ Subdivision on Floodplain Farmland — A Risk Rebranded

Many housing estates from Caboolture to Camden Haven are now built on low-lying farmland previously used for grazing or sugarcane. These lands are:

Naturally saturated.
Close to creeks or rivers.
Prone to overland flow and flash flooding, especially during La Niña years.

Developers make these sites work using civil works, detention basins and engineered fill to meet stormwater discharge requirements. But unless there's site-specific flood modelling and floor levels planned house by house, many homes are left exposed even when the estate is technically compliant.

🔍 Drainage Often Left to the Individual Lot

In these new estates:

There’s usually no consistent fall across multiple blocks.
Drainage is often left to each builder, who designs for their lot without considering the neighbour’s overflow or the original natural flow paths.
Many councils don’t enforce inter-lot drainage plans, especially after subdivision approval.
Builders then pour slabs without adequate fall or berms, relying on “future landscaping” to solve drainage later—which rarely happens properly.

🏛️ Councils Focused on Planning Codes, Not Performance

Planning schemes tend to focus on:

Road connectivity.
Minimum lot size (yield for developers).
Open space percentage.

But drainage and water movement across sites is too often treated as a box-ticking exercise handled by the civil contractor—and forgotten by the time homes are built.

The result? A whole suburb can tick every box on paper and still fail in a storm. And who's to blame? Nobody, because everything met the standards. Your insurer won't care either. The homeowner pays through higher premiums, if they can get cover at all (and you need it for your bank loan).

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Subdivision layout can set your home up to flood before it’s even built.
Steep slopes, shallow “cut and fill” lots, and floodplain farmland all create water movement challenges—but drainage is often left to individual builders, with little council oversight after roads are in.

6. Box-Ticking Culture — Minimum Compliance Is the Standard ✅📉

In theory, the building code and planning rules protect people and property. In practice, they've become the floor, not the foundation for quality.

Across the industry there's a culture of doing just enough to pass: minimum slab heights, token drainage, questionable flashings and cheaper substitutions.

🧱 “What’s the minimum I can get away with?”

Builders under time and cost pressure (especially in the volume market) often approach every decision with a minimum viable product mindset:

Slab just 100 mm above ground? Tick.
No strip drain at flush entry? Tick.
Roof flashings not sealed but technically “present”? Tick.
Paving falls toward the house, but it passed certifier sign-off? Tick.

No one is rewarded for doing better. In fact, exceeding standards is seen as too expensive or too slow—especially when competitors aren’t doing it.

🕒 Fast Builds, Fast Failures

In an environment where houses must be finished in 12–16 weeks to meet funding deadlines and workflow quotas, quality control gets squeezed out.

Certifiers, often engaged directly by the builder or developer, are incentivised to approve quickly. Homeowners usually don’t realise something was missed until after the first big rain.

There’s no margin for craftsmanship. Only compliance.

🗨️ Dusty’s Quote

To borrow from Dusty, the SES volunteer in Wauchope:

“There’s no hope to stop the water if it’s built like that from day one.”

And that’s the hard truth. Once the slab’s down and the paving’s done wrong, it’s already too late.

🔄 The Consequences

This culture of minimums means:

Homes pass inspections but don’t perform in real-world conditions.
Builders avoid liability by claiming code compliance.
Insurers wear the loss—until they pass it back to homeowners via premiums.
Public trust in new housing quality continues to erode.

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“Compliant” doesn’t mean “fit for purpose.”
Today’s building culture rewards the bare minimum. If the design isn’t right for the site, or drainage is skipped to save costs, homes may flood—even if every box was ticked.

7. Industry Messaging — “Let Builders Build” Is a Red Flag 🚩🧱

If you've read the industry press or listened to lobby groups lately, you'll have heard the latest line:

“We need to cut red tape.”

“Builders know what they’re doing — get out of the way.”

“We can’t fix the housing crisis if you keep slowing us down with regulations.”

It sounds reasonable. We're in a housing supply crunch and we need more homes. But it sets up a false choice between speed and quality, and it's increasingly used to justify removing the oversight, inspections and protections that prevent disasters like flooded homes.

🏚️ What Deregulation Really Looks Like

In the past few years, we've seen:

Private certification promoted over independent council inspections.
Performance solutions replacing prescriptive requirements — allowing loopholes and “creative” interpretations.
Shorter assessment time frames, limiting council planners’ ability to review site-specific drainage or slope issues.
“Self-certification” allowances, where builders sign off their own work.

Each of these steps removes a layer of accountability — in the name of “efficiency”.

📣 Who Benefits From Faster, Less Scrutinised Builds?

The builders? Maybe.
The developers? Almost certainly.
But the homeowner? Rarely.

You’re left with homes that pass on paper, but leak at the first big storm.
Drainage that looks fine on the DA but fails in the driveway.
Slabs poured to “minimums” that don’t survive landscaping.

And when it all goes wrong, the messaging flips:

“Well, it was signed off by… so it’s not our fault.”

🧩 Undermining Public Trust

When industry bodies push to remove rules, reduce inspections, or streamline everything, they frame it as a fix. But to many homeowners — especially those whose homes have already flooded — it feels like a system doubling down on failure.

Without independent checks, robust standards, and real consequences, the gap between what’s approved and what works continues to widen.

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“Let builders build” sounds like progress — until your lounge floods in its first summer. Speed without scrutiny creates risk. We can build faster without building worse — but not by removing every safety check along the way.

8. Responding to Damage Instead of Preventing It 🔁🚨

Australia is good at responding to disasters: SES callouts, clean-ups, emergency funding and buybacks. We're much worse at prevention.

Instead of designing homes and planning suburbs to withstand extreme weather, we rely on:

Insurance claims,
Government compensation,
Disaster declarations, and
The community spirit of volunteers to mop up the mess.

It’s reactive, expensive, and often traumatic.

🧹 Buybacks, Floodgates, and the High Cost of Cleanup

Take Lismore. After the 2022 floods, the NSW and federal governments funded an $880 million Resilient Homes Program to buy back, raise or retrofit flood-prone homes.
Many of those homes were decades old, and some had been rebuilt after earlier floods. What if better siting, higher slabs or drainage enforcement had been required at the rebuild?

Or Maryborough, where the levee system failed and CBD businesses flooded again. Engineers had warned of weaknesses, but repairs weren’t made. Response came after disaster — again.

💰 The Real Cost of “It’ll Be Right”

Emergency response is expensive, and it's demoralising and cyclical:

Homeowners suffer losses, twice.
Insurers raise premiums or withdraw entirely.
Councils pay out or repair public assets.
State and federal governments foot the rest.

Meanwhile, builders and certifiers often walk away — protected by limited liability or the simple excuse of “code compliance”.

🧠 A Smarter System Is Possible

Flood-resilient design isn’t rocket science:

Raise slabs based on flood overlays and real drainage patterns.
Install strip drains where water will flow.
Use site-specific assessments — not cookie-cutter designs.
Require real inspections — not just paperwork sign-offs.

Yet in most jurisdictions, these measures aren’t mandated. They’re optional. And when left optional in a race-to-the-bottom market, they’re usually skipped.

⛑️ The SES Should Be the Last Resort

Volunteers like Dusty — who spend weekends wading through flooded lounge rooms — should be responding to unexpected weather events, not predictable design failures. Every time a new home floods in a mild storm, it’s not nature’s fault. It’s ours.

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Disaster response isn’t a plan — it’s an admission that planning failed.
We can’t keep relying on buybacks, bailouts, and brooms. Preventing flood damage costs less than fixing it — and it protects lives, homes, and public trust.

A truly national code would help too. Every state can vary the NCC, so a builder can meet one set of rules in WA and another in Queensland even where the flood risks are similar. One national code, adjusted only for climate zones, would make it far easier to lift resilience everywhere. For now the direction is the other way: building ministers have agreed to make no further residential NCC changes, other than essential safety and quality measures, until mid-2029.

9. Insurance Premiums: An Indirect Tax on Poor Construction 💸🏚️

When builders cut corners and certifiers wave it through, it's not them who pays when things go wrong. It's you, through higher premiums, reduced cover or rejected claims. In effect, homeowners pay a stealth tax for poor construction oversight. Banks, valuers and governments all benefit from rising property values, even in flood-prone areas, while the homeowner carries the long-term risk.

💥 What the Numbers Say

Water damage (including storm and flood ingress) is now one of the top claim categories. Some figures:

The average internal water damage claim is now over $30,000, and rising.
In high-risk postcodes, premiums have increased by more than 50% in the last five years.
In flood-prone zones like Lismore, residential policies have been withdrawn entirely by major insurers—or offered at unaffordable prices.

When a new home floods because the slab was too low or the paving fell toward the house, the builder can still argue it was technically compliant. The claim lands on your insurer, not the people who built or approved the problem. That's a classic moral hazard: those best placed to reduce the risk don't suffer the consequences.

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Insurance is becoming a backdoor tax on bad building practices.
Homeowners pay more—not because their home is old or broken—but because the system let new homes be built poorly in the first place.

10. What Homeowners and Buyers Can Do Right Now 🏡🔍

You're not powerless. Whether you're buying, building or already living in your home, there's plenty you can do to protect yourself from water damage.

🗺️ Before You Buy: Know the Land

Check flood overlays. Every local council provides flood mapping (sometimes under “flood hazard overlays” or “overland flow paths”). It shows known risks based on 1% AEP events or historical flooding.
Review site contours. Sloped sites can create runoff issues even if they're not flood zones.
Ask the right questions. What’s the site’s Finished Floor Level (FFL) in AHD? Has flood modelling been done? Is the developer using cut-and-fill pads?

📝 Tip: If slab RL is described only as “X mm above NGL,” push for clarification in AHD. This is the only meaningful way to confirm elevation against known flood levels.

📐 During Design & Construction: Put It in Writing

Include slab height clauses in your building contract — e.g. “Slab RL to be not less than 300 mm above adjacent ground level and 500 mm above known flood level where applicable.”
Ask for drainage design drawings. Most builders won’t provide them unless prompted — insist on a stormwater plan that shows fall, surface gradients, and stormwater connection points.
Engage an independent inspector (not the builder's certifier) to check slab heights, site fall and downpipe connections before frame stage.

Carry out a stormwater test at handover. A simple hose test around the house can reveal whether water runs away from or toward your slab.

🧽 After Handover: Maintain and Monitor

Yes, your house needs maintenance, and you need to keep an eye on how it performs over time.

Keep garden beds, mulch, and paving at least 75–100 mm below the slab edge to prevent bridging.
Watch for “landscaping creep” — where soil, turf, or paving slowly builds up to match slab height, eliminating the freeboard.
Inspect flashings and gutters annually. Look for corrosion, lifted edges, or signs of water marks at eaves.
Install or improve overflow paths — especially if your home has parapets or is lower than neighbouring properties.

🔍 Final check: Use a level or phone app to confirm water falls away from the house perimeter. If not, re-grade.

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You can’t control what your builder does — but you can control what you ask for. Insist on slab RLs in AHD, drainage plans in writing, and independent inspections. The best time to prevent flooding is before the water arrives.

Conclusion – Raise Standards (and Slabs) So the SES Can Stay Home 🛌🚫🌊

The image of SES volunteers like Dusty wading through ankle-deep water in brand-new homes isn’t just heartbreaking — it’s preventable. And it should be unacceptable.

The SES runs on a shoestring, with few full-time staff and mostly volunteers. They tarp roofs, haul sandbags and pump out homes that should never have flooded.

The uncomfortable truth? Not fixing this may be a political choice. Higher slab levels, mandatory drainage design and more inspections would raise building costs, which isn't popular with voters. It's easier to keep the rules soft and let the SES pick up the pieces. In the long run, everyone pays more: homeowners through losses and premiums, taxpayers through recovery funding, and volunteers through burnout.

If we raised standards and designed for the real risks, the SES could focus on genuine emergencies — not mopping up failures that were “compliant” from day one.

We’re not dealing with “acts of God” — we’re dealing with acts of omission.

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Flood resilience isn’t about luck or the weather — it’s about smarter choices at the design and construction stage. Raise your slab, fix your drainage, and demand more from the people building and signing off your home. Yes, it will cost more upfront. But you’re already paying for poor design through higher premiums and repair bills — just without the benefit of avoiding the damage in the first place.

💬 Frequently Asked Questions (FAQ)

1. Is a 250 mm slab height above ground level mandatory in Australia?

No. The NCC requires the slab to be 100–150 mm above finished ground depending on site conditions, or 50 mm above paving that slopes away from the house. In flood hazard areas in Queensland, QDC MP 3.5 or the council planning scheme typically requires floors 300 mm above the defined flood level.

2. What’s the difference between NGL and AHD when setting slab levels?

NGL (Natural Ground Level) is the unmodified ground level at the site.
AHD (Australian Height Datum) is a nationally consistent elevation reference.
For flood resilience, slab RLs should always be stated in AHD, as it allows accurate comparison against flood modelling and overlays.

3. Are private certifiers allowed to approve drainage and slab heights without inspections?

Not in Queensland. The Building Regulation 2021 requires stage inspections for new houses (excavation, footings or slab, frame and final), although some can be done by a 'competent person' for the certifier. But those inspections are snapshots. They generally don't check your drainage design or site falls in detail unless a development approval condition requires it, so ask for a drainage plan and consider an independent inspector.

4. My builder said my site isn't in a flood zone — do I still need to worry about slab height?

Yes. Even if your lot isn't in an official flood zone, overland flow, poor drainage, and site cut-and-fill practices can create water risks. Always request a site-specific drainage plan, and consider raising the slab height for added peace of mind.

5. Do SDA (NDIS) homes really risk flooding because of accessibility design?

They can. While SDA design guidelines promote zero-threshold entries, there are loopholes where drainage isn’t required for porches over 1800 mm deep. Without strip drains or proper grading, these entries can funnel water into the home.

6. Should the council be responsible for drainage issues between lots?

Not always. Councils approve subdivisions and may specify basic drainage requirements, but individual lot drainage is often left to builders, who may not consider how neighbouring lots interact. That’s why inter-lot drainage planning is crucial.

7. Can I ask for a slab height clause in my building contract?

Absolutely — and you should. Include a clause specifying that the Finished Floor Level (FFL) must be a minimum of 300 mm above surrounding finished ground or 500 mm above flood level (if applicable), and must be shown in AHD on the site plan.

8. Are rising insurance premiums really linked to poor construction?

Yes. Insurers base premiums on risk, and poor drainage, low slab heights, and water ingress risks increase that. In high-claim suburbs, insurers may withdraw cover entirely or impose excesses. In that way, insurance becomes a cost on system failure.

9. I’m not building — can I still protect my existing home from flooding?

Yes. You can:

Regrade paving to fall away from the house,
Install strip drains at doors and driveways,
Lower soil or mulch beds away from slab edges,
Keep gutters clean and add overflows,
Add a sump and pump with a lay-flat hose if you know water will collect.
In rural or larger properties, create bunds or small dam areas to redirect or temporarily store stormwater away from the house. 👉️ See the video below for the mother of all dams — and how it stopped water from getting in.
And check flashings annually for leaks or corrosion.

10. Who can I talk to if I’m unsure about my home’s drainage or flood risk?

Independent building inspectors can assess slab heights, site fall, and roof drainage.
Local council flood engineers can explain overlays and flood levels.
Hydraulic designers or engineers can model water flow specific to your lot and home.