If you’re planning to renovate in the Inner West Council area, and your property is located in a flood-prone zone, there are additional requirements you’ll need to meet to ensure your project complies with council regulations. Flood zone restrictions are designed to protect both your property and the community from the impacts of flooding, ensuring that renovations are carried out safely and sustainably.
In this post, we’ll walk through what you need to know about flood zones, the required certificates, and the key design and compliance considerations for renovations in flood-prone areas of the Inner West.
What is a Flood Zone?
A flood zone refers to areas that are prone to flooding during significant rainfall events. These areas are mapped and designated by the council to help manage flood risks. In the Inner West, flood-prone land is identified on a Flood Control Lot Map.
Floods can happen as a result of heavy rainfall, overflowing rivers, or tidal inflows. Being in a flood zone doesn’t necessarily mean you can’t renovate, but it does mean that your project will need to comply with specific flood management controls.
Flood Certificate: Your First Step
Before you begin any renovation plans, it’s crucial to obtain a Flood Certificate. This certificate provides important information about the flood risks affecting your property and is required for any development applications in flood-prone areas.
The Flood Certificate will include:
- The likelihood of flooding - (known as the ‘Annual Exceedance Probability’ (AEP). This is the probability that a flood of a given (or larger) size will occur within a period of one year. For example, a 1% AEP Flood means you have a 1-in-100 chance that a flood of that size (or larger) could occur in any one year.
- Flood levels specific to your property - the depth of flooding for the 1% AEP event and the Probable Maximum Flood (PMF)
- Flood hazard categories
- Information on overland flow paths
You can apply for a Flood Certificate through the Inner West Council website, and it will be a key document in determining the specific controls that apply to your renovation.
If you are undertaking a project with Banksia Building Design, we can arrange this for you and help explain what it means for your property.
Flood Planning Levels and Building Requirements
If your property is flood-prone, there are strict regulations regarding how high your home’s floor levels need to be. These levels are based on the Flood Planning Level, which ensures that habitable rooms are built above the flood level to reduce the risk of damage in the event of a flood.
For most residential renovations, the floor levels of habitable rooms must be at least 500mm above the 1% AEP flood level. This means if the council determines that your property has a flood level of 2 metres, your renovated home’s living areas would need to be 2.5 metres or higher.
For areas with minor overland flow (shallow floodwaters), a lower clearance (freeboard) of 300mm may be considered, depending on your specific circumstances.
Using Flood-Compatible Materials
Another key requirement for renovations in flood-prone areas is the use of flood-compatible materials. These are materials that can withstand the effects of flooding, such as immersion in water, and won’t deteriorate if exposed to moisture or flood conditions.
Examples of flood-compatible materials include:
- Concrete flooring or ceramic tiles that won’t warp or degrade when wet
- Solid brickwork or reinforced concrete for walls
- Metal doors or aluminium window frames that resist water damage
Using these materials in areas that are vulnerable to flooding will not only help protect your home but also reduce long-term maintenance and repair costs.
Designing for Flood Zones: Practical Strategies
Designing a home in a flood-prone area doesn’t mean sacrificing functionality or style. With thoughtful design strategies, you can create a beautiful, functional space that also meets flood compliance requirements.
Here are a few common strategies for renovations in flood zones:
- Raising Floor Levels: As mentioned, ensuring that habitable rooms are elevated above the flood planning level is a crucial requirement. This often involves adding extra height to foundations or reworking the layout to place living areas on higher levels.
- Wet-Proofing: Wet-proofing allows areas of your home that may be exposed to floodwaters (like garages or basements) to flood without significant damage. This can involve using materials that can get wet without deteriorating and ensuring that electrical and plumbing systems are waterproofed and above flood level.
- Dry-Proofing: In some cases, dry-proofing techniques may be used to prevent floodwaters from entering the building. This can include the installation of flood barriers or specialised sealants to block water from entering at vulnerable points.
- Improving Drainage and Overland Flow: Managing how water flows around your property is essential in flood-prone areas. Incorporating proper drainage systems and ensuring overland flow paths are maintained can help reduce the risk of water pooling and flooding your home.
Flood Risk Management Report (FRMR)
For properties identified as being at higher risk of flooding, a Flood Risk Management Report (FRMR) will be required. This report, prepared by a qualified engineer, assesses the flood risks specific to your site and outlines strategies to manage these risks.
The FRMR will typically include:
- Information on the local stormwater drainage system
- The extent of the 1% AEP flood event in the area
- Flood hazard categories affecting the property
- Recommendations on materials, waterproofing methods, and evacuation strategies
This report is a key part of your Development Application and will help ensure that your renovation meets council requirements for flood-prone areas.
Some types of development such as an increased floor area can mean there is less ground area for flood water to flow over. This can result in increased flood water depths. Council takes this into consideration when assessing flooding to ensure your project will not worsen the situation for surrounding properties.
Common Challenges and Solutions
Renovating in a flood-prone area comes with its challenges, but there are ways to overcome them while maintaining the integrity and safety of your project. Here are a few common challenges and how they can be addressed:
- Challenge: Minor Overland Flow
Solution: For areas with minor overland flow (flood depth under 300mm), it may still be possible to proceed with renovations. By using appropriate materials and ensuring that floor levels meet the council’s minimum height requirements, you can minimise flood risk while continuing with your project. - Challenge: Low-Lying Garages or Carports
Solution: Garages and carports in flood zones need to be carefully designed to allow for water flow. In some cases, raising the floor level slightly or incorporating drainage solutions can reduce the risk of damage. - Challenge: Neighbouring Properties
Solution: When renovating in a flood zone, you’ll need to ensure your design doesn’t increase flood risks for neighbouring properties. This often involves careful consideration of drainage and overland flow paths to prevent water from being redirected to other areas. Expert flood consultants can assist with this and run computer generated models simulating the flood flow with your project to review it’s impacts.
Conclusion
Renovating in a flood-prone area in the Inner West Council region requires careful planning, but with the right approach, you can create a beautiful and functional home that also meets flood compliance regulations. By obtaining the necessary flood certificates, using flood-compatible materials, and incorporating thoughtful design strategies, you’ll be well-equipped to handle the unique challenges of renovating in a flood zone.
If you’re considering a renovation and need expert guidance on how to navigate flood zone restrictions, Banksia Building Design can help. We have extensive experience working within Inner West Council’s flood management controls and can assist you with designing a compliant and stylish renovation.
