Flood Prone Land & Granny Flat Approvals NSW

How To Get Granny Flat Approval with Flood Prone Land

I’ve been meaning to write a guide on how to get granny flats approved in flood prone land for a long time now but, to be honest, I’ve been dreading it a little. It’s not a simple topic and despite my training as a high school teacher, this might be our most difficult guide yet! Luckily I love a challenge, so here goes!

Flood Prone land Granny Flats

So today you’re going to learn about flood-prone land in NSW and how you can get your granny flat approval quickly, cheaply and efficiently.

Flood Prone Land – Fast SEPP Approval

For fast SEPP approval, we need to prove that the site is not in any of the following as per the Main SEPP (Clause 3.36C):

(a) a flood storage area,

(b)  a floodway area,

(c)  a flow path,

(d)  a high hazard area,

(e)  a high risk area.

How Do I Prove SEPP Compliance?

The process in proving your property is SEPP-Compliant is as follows:

1. Check Section-10.7 (part 5) Certificate under Clause 7(A). This clause lists the severity of flooding. If it says the site is medium or low risk flooding, this is good. If it also states the site is affected by Overland Flooding’ or that it’s in a ‘Flow Path’, your property won’t qualify for fast SEPP compliance. A DA and CC will be needed.

2. Call Council and talk to the ‘Flooding Engineer’. When you call, be sure to ask him/her for  the property’s “Flood Info“. There may be a fee associated with this enquiry at some Councils but it’s invaluable information which you’ll need to give to us. We can also get this information for you.

3. Check Council’s website and search ‘flood maps’. These maps usually do not list the severity of flooding; they simply show whether or not the site is flood affected and which part is affected (if partial). The affected area is usually shaded blue.

In my experience, the most useful information comes form step 2 above. A Flood Info enquiry which will come as a written document and a map, will often be enough for an experienced Architect or Engineer to critically assess. If the site is NOT in one of the five categories listed above, you’ll be able to avoid a DA/CC which is good news – you’ll save considerable time and money!

My Land is SEPP Compliant. Now What?

If your land is SEPP-Compliant, we simply need to carry the work listed below:

1. We carry out an AHD Survey. These cost around $1,300 for the average Sydney residential  property including the relevant research and reports we must do. Once we have this done, we can check the site’s levels (NGL) against the Flood Info Report from Council to see how high (FFL) above the natural ground we need to build your granny flat.

2. We prepare your Architectural Plans as normal, except we make sure the FFL is at the (PMF or Freeboard) Level set by Council in their Flood Info Report and we plot it on the AHD Survey (above).

3. We hire a  Hydraulic Engineer (costs $980) who will check our plans and issue us a SEPP  ‘Flood Certificate. This is a written statement which certifies that the proposed structure is complaint with the SEPP Legislation and that it will withstand flooding.

CONGRATULATIONS! You have now resolved your flooding issues!

What If My Flood-Prone Land is NOT SEPP Compliant?

If your land is is proven to be in one of the five categories listed above, we need to carry out a DA (Development Application and CC (Construction Certificate). We need to carry out the following additional work:

1. The Architectural Plans must be much more detailed plus we need to submit additional documents when submitting a DA and CC Application. These extra documents include various Compliance & Environmental Statements, an Engineer’s Hydraulic Plan, a Site Management Plan, a Soil and Water Management Plan, a Construction management Plan, Shadow Diagrams, a Landscape Plan, a Waste Management Plan, Materials and Finishes Statements and a landscape Plan to name a few. This additional work costs around $3,800 extra.

2. The Time-frame for this path is considerably longer and your neighbours will be notified during the process and be given the opportunity to object tot he development.

3. There are No Guarantees with a DA but we always contact Council first to gauge their position on the prospects for approval. It’s worth noting that flood-prone sites which are High-Risk Flooding can be refused if the FFL will be too high. In these cases, we might look at a skillion roof in order to minimise the impact to neighbours. You can read about the different roof types in this guide.


All prices are correct at the time of writing this guide (June 2014) & they do include gst.

1. Section-10.7 (part 5): $133

2. Council Flood Info Advice: ranges from $0 to $200

4. Hydraulic Engineer’s Certificate: $980

5. AHD Survey, Architectural Plans, BASIX, Structural Plans, Fully Certified Approval: Approx. $7,480

TOTAL APPROVAL COST: Approx. $8,560 incl gst

TOTAL TIME TO APPROVE: Approx. 6 weeks


All prices are correct at the time of writing this guide (June 2014) & they do include gst.

1. Section-10.7 (part 5): $133

2. Council Flood Info Advice: ranges from $0 to $200

4. AHD Survey, Architectural Plans, BASIX, Structural Plans, DA Submission Documents: Approx. $11,800

5. Engineer’s Hydraulic Design & Certificate: Approx $1,200

5. Council DA and CC Fees: Approx $2,400

TOTAL APPROVAL COST: Approx. $15,400

TOTAL TIME TO APPROVE: Approx. 8 to 12 weeks

Are There Any Additional Construction Costs?

If Council set the Freeboard FFL quite high above the NGL (Natural Ground Levels), you may be up for some pretty tall foundations. In these cases the cost of your granny flat slab foundations may increase as follows:

1. Up to 200mm above NGL’s: $0

2. Up to 400mm above NGL’s: Approx. $3,000

3. Up to 600mm above NGL’s: $Approx. $6,000

Note: If the site is in an ‘Overland Flow Path’, Council will probably require us to build on brick, masonry or brick piers in order to allow the flow of water through the property.

Some Known Flood-Prone Areas in NSW

Here’s a list of some of the most commonly flood-affected Council areas that I know of in Sydney:

1. Auburn (Lidcombe Central, Auburn near M5 Motorway)

2. Fairfield (Lower Canley Vale, Lansvale, Carramar)

3. Holroyd (South  Granville, Merrylands)

4. Wollongong (Central Escarpment areas)

5. Campbelltown (Lower Glenfield- near railway Station)

6. Bankstown (Lower Panania, Lower East Hills and lower Padstow, near M5).

If you know of any other suburbs which are commonly flood-affected, please let me know in the comments below and I’ll add them to the list!

A Note to Property Hunters

To our investors, I’ll just add that when you’re out property-hunting, be very aware of Clause 7(a) in the Section-10.7 Certificate, but don’t be totally discouraged if it says ‘yes’ under flooding. If the site is not too severe, it may just scare off the other investors and allow you to grab a bargain on auction day. Just be sure to invest in the crucial checks I’ve written about in this flooding guide and you” be the smartest investor in the pool. A ‘high-risk’ or ‘overland flow-path’ property is a more risky proposition and can be an expensive property to deal with. You can always give me a call and I’ll gladly check it for you.

Here’s just two examples of Sydney Granny Flats we built in flood-prone areas:

Glenfield NSW: This property was in an ‘Overland Flow Path’ and ‘Hish-Risk’, hence the high piers.

Panania, NSW: This property was in a ‘Floodway Area’ but it was Low-Risk Flooding, hence the lower (500 mm high) slab.

It’s also important to understand some important terminology. Below, I’ve listed the more important words used in the Hydraulic Engineering World. If you get lost whilst reading my flooding guide just refer back to these definitions, which will come in very handy as you go through this guide.

Flood Prone Land – Critical Terminology

Flood Prone Land: Land that your Local Council has ruled to be at risk of flooding.

Overland Flow Path: The path by which water will pass on its way to other land. Affected properties need to ensure the flow of water is not blocked and is allowed to pass through the property.

Flood Storage Area: A parcel of land which receives a volume of flood water and holds it there for some time before it dissipates.

High Hazard Area: As opposed to a low-hazard and medium-hazard area, these areas  are at high risk of flooding.

AHD Level: This is a number which defines the height of a point on a property above mean sea level. Example is an AHD level of 14.55 which means that point is 14.55 metres above sea level.

1 in 20 Year Flooding (ARI): This is the AHD level which Council believes will have a 1 in 20 chance (every year) of flooding your site.

1 in 100 Year Flooding (ARI): This is the AHD level which Council believes will have a 1 in 100 chance (every year) of flooding your site.

AHD Survey: A Site Plan which shows all of the AHD levels on your land.

NGL (Natural Ground Level): An existing level at any given point on your land.

FFL (Finished Floor Level): This is the height of the floor for a granny flat. We draft plans to a particular Finished Floor Level on your land, as given to us by Council.

Free Board Level: This is a safe level (usually 500mm above the 1:100) which Council tells us to set your FFL at.

PMF (Probable Maximum Flood): This is the AHD level which Council tells us will be the highest possible flood level on your land – ever.

Structural Piers: A foundation system where the structure sits on ‘legs’ as opposed to sitting on a concrete pad or slab. This is usually required in an overland flow path.

Hydraulic Engineer: A person who has a degree in Hydraulic Engineering and is qualified to design and certify a structure as habitable.

Section-10.7 Certificate (S10.7 – Part 2): The Certificate in your Contract of Sale which lists zoning and other info, including a quick summary about flooding risk on your land.

Section-10.7 Certificate (S10.7 – Part 5): This is the more detailed S10.7 Certificate which provides more detail about flooding on your land, specifically under Clause 7(a). Unfortunately, most Contracts of Sale only have the Sectiion-10.7 (part 2) in them , so the S10.7(5) often needs to be bought separately from Council. These costs $133 as of June 2014.

Council Flood Map: A Map showing all the land in your area and whether your site is affected by flooding or not.

‘SEPP’ Approval Path: The approval path we love to take because it’s guaranteed to succeed. This path is much faster and much cheaper than a DA/CC approval path. The SEPP path is also fully guaranteed to succeed and no one can object to the development – not even a Council!

DA & CC Approval Path: A DA & CC is the approval path needed when a property is severely affected by flooding. A DA and CC (Construction Certificate) is submitted through your Local Council which costs more than a SEPP Approval and takes longer to approve.



This guide is a summary of the knowledge and experience I have gained from many years in the industry. Whether you are a Builder, Owner-Builder, Architect or one of our Customers that I have referred this guide to, I certainly hope this info helps you to understand flooding and the process we use to mitigate it.

Flooding issues are probably one of the trickiest to understand. If you have any questions or you’d like to let me know if this guide helped you, please write a comment below. I’d really love to get your feedback!


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14 replies on Flood Prone Land & Granny Flat Approvals NSW

  • Sue says:

    Penrith council have told me that I cannot build a granny flat on my block as they have put a limit on the number of people able to live in Emu Plains due to flooding & not being able to evacuate them if it ever flooded.For the life of me I can’t work it out.I can build as many bedrooms & bathrooms as long as they are attached to my house but no free standing dwelling.Have you ever come across this & how do I approach granny flat building?

    • Serge Panayi says:

      Hi Sue, I am aware of this problem in the Emu Plains “Flood Evacuation” Area and I’ve tried a DA to get a Granny Flat Approval but failed,. The client wanted me to try but it was unsuccessful. Frustrating I agree!

  • Angela says:

    Hi Serge,
    My house is ” Low Flood risk precinct” that is results on online search in Council website..
    Question: Is there any impact on granny flat building? Do i need to apply for Flood Infor. Letter from council (section 10.7 -part5 ???) before your making decision?
    Thank so much.

    • Serge Panayi says:

      Hi Angela,

      Low Flood Precinct is usually not such a bad thing. It may mean as little as having to just pay for the more expensive Section-10.7 (part 5) Certificate. Best way is to just get it for now and then an assessment of any other compliance/build costs can be determined. We do this type of assessment all the time and endeavour to do it all to minimise and save all future costs for the client.

      So, yes, by all means get the S10.7 (part 5) first. If you like we’ll be happy to asses/quote for the approval and/or build if you need the service.
      Thanks Angela,

      Serge Panayi

  • FH says:

    Hi Serge: This is a great article. We are considering to buy a property which is located in a ‘high flood risk’ precinct in NSW. I have sent the 10.7/2/5 certificate to you via sales@grannyflatapprovals.com.au. Would you please advise me further on the possibility of a granny flat in that plot?

    • Serge Panayi says:

      Hi FH,

      We’re looking at it now for you but I’m not hugely optimistic at this stage – ‘High Flood Risk’ often means no SEPP Approval BUT we may be able to do something under a DA/CC. This is a riskier and much more expensive route with no guarantees of success. The severity of flood risk can vary from Council to Council and type of risk so let us take a look and get back to you. We’ll help you to assess the risk against the purchase price and against the additional approval/construction costs on this particular property.

      We’ll do all of this quickly for you so that you can make a timely and informed decision before you purchase.



  • Bonde Ilievski says:

    Hi Serge,
    I own a property which is flood affected in wollongong. There is an existing Shed approx 14mx8m x 4m high at the rear of the property and a medium/high flood risk rating.
    The PMF is about 700mm above the slab level of the shed, The shed is approx 300mm-500mm off the boundaries. If I wanted to build a granny flat within the shed and alter the shed would this qualify under the sepp?

    • Serge Panayi says:

      Hi Bonde,

      I’m afraid not because the PMF is for habitable buildings so the dwelling would be vulnerable to flooding at the floor level.



  • Rajneesh says:

    Hi Serge,
    I own property (corner lot) in South Wentworthville which is flood affected and I got flood report from council and it is marked as medium risk (1% AEP). Can i get fast SEPP approval for Granny flat?

    • Serge Panayi says:

      Hi Rajneesh,

      It will most probably require a DA as opposed to fast SEPP approval BUT there are rare cases where we can get a Certificate from an Engineer which re-qualifies the property for SEPP approval.

      Give us a call and we can check it for you.


  • Pete says:

    Hi Serge, great write up, very helpful.
    My property is located in a flood zone, low hazard 1%AEP and freeboard. My original plan was to sub-divide and build but having trouble getting the sub-division through council due to not having a safe, low hazard evacuation route in the event of a 1 in 100 flood. The property itself is ok, but the road becomes inundated.
    Does the CDC application take into consideration evacuation routes or just the land you are proposing to build the granny flat on? Thinking this may be my back up option if council refuse the application.

    • Serge Panayi says:

      Hi Pete,

      I’m afraid a CDC might not be permissible on your lot due to the evacuation zone. Your best bet is to ask Council if the property qualifies for CDC development. They will be able to tell you.


  • Gunawan Samahita says:

    Hi Serge,
    Thank you for such a detail article about this subject. My property is at Denistone East NSW 2112 and Flood Report it is classified as ; Flood Risk: Low to Medium. The site affected by overland Flow Path .
    So, I suppose I have to go through DA. From your experience what is the chance to get approval ?
    Thank you,

  • Matthew says:

    Hi Serge,
    We wanted to build a granny flat on our property in Hornsby council and the granny flat is located on a over land flow path. Given the high volume of peak flow, and the position of the proposed development, monolithic slab-on-grade construction was deemed unsuitable due to the increase in flood affectation on neighbouring properties. A permeable open sub-floor
    construction methodology was prescribed and floor level raised to meet requirements. However our proposal was still rejected. Council noted the proposal does not comply with the desired outcomes and the prescriptive measures of Part 1C.3.2
    Flooding under the Hornsby Development Control Plan 2013 which encourages development that is located and designed to minimise the risk to life, property, and the environment from flooding. Have you had experience on any other solution that may get us the approval we needed? Thanks!

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