Flood resilience for the building and construction industry

An introductory guide to help builders, architects, engineers and trade contractors prepare their client’s properties for flooding events.

Getting started

There are many things to consider to start improving flood resilience for your clients, starting with the below:

What is flood resilience – It’s important to understand the principles and definitions of flood resilience.
Understand flood risk mapping – In order to prepare a property for flooding, you first need to know what type of effect flooding will have on the property.
Different flood resilience strategies available – Understanding what strategies are available will help you recommend the most suitable flood-resilient solutions for your clients.

What is flood resilience?

In many cases, it’s not possible for your clients to completely avoid flooding. Flood resilience offers a cheaper and more convenient way for residents and businesses to work with the building industry and prepare their property for flooding.

Flood resilient design uses materials, construction techniques and design choices that can withstand substantial and multiple water inundations to actively mitigate the effects and minimise the cost of flooding. Flood-resilient design, provided by trade contractors, enables property owners to easily clean and move back in quickly after a flood event with minimal long-term disruption. By implementing these measures, homeowners can actively mitigate or minimise the effects of flooding and in some cases, can even reduce their insurance premiums. See below for some key definitions regarding flood resilience.

Wet-proofing

Wet-proofing is the recommended flood resilience strategy for Brisbane properties. Wet-proofing is adopting design and building techniques that can withstand multiple and prolonged inundations of water in a flood event. This can be applied to internal and external structures and surfaces. The ultimate goal of wet-proofing is for clients to clean out their property following a flood event and return to normal routines with minimal time and money spent in the process.

Dry-proofing

Dry-proofing is designing and constructing a property to entirely prevent flood waters from entering. Due to Brisbane’s location on a floodplain, drainage systems and unique land features, flood events can be unique and unexpected. Due to this, it is difficult to guarantee that dry-proofing techniques will always work for your clients and therefore, it is not recommended for Brisbane properties.

Why consider flood-resilient strategies for your clients?

There is a growing demand for flood and climate-resilient strategies when renovating and building new homes. While this is a long-term trend, it has particularly increased since the February 2022 flood event.

Customers want a home where they feel safe and have peace of mind that their investment is protected. By proactively offering flood-resilient outcomes for your clients, you are positioning your business as one that’s up to date with current building techniques that consider sustainability and future-proofing your customer’s property against potential flooding.

Understanding flood risk

It is important for you and your client to understand the likelihood of flooding for their property and local area so you can know how high to design flood-resilient building strategies to. Ensure that you and your client have done the steps below.

Understand the flood risk of the lot

Use the Brisbane City Council’s Flood Awareness Maps for the Brisbane area and download a FloodWise Property Report for the address you’re working on. This will tell you what chance of flooding the entire property has, what type of flood can affect the property and what height waters might rise to.

To learn more about the types of flooding featured in a FloodWise Property report, visit the Brisbane City Council Flooding in Brisbane Guide for Residents.

Understand the flood risks and levels of the building

Next, have your client engage with a property-level surveyor to determine the exact habitable floor levels of the property.

Then you and your client can match the flood water levels of the land to the habitable floor levels of the property. This will show you what chance of flooding the property has and to what height the water levels might rise. The FloodWise Property Report will supply different percentage chances of flooding at different heights.

Remember, the FloodWise Property Report will give you an estimated flood level based on previous floods and modelling data. However, every flood is unique and there is a chance that the next flood event may reach a higher peak than estimated. Therefore, it is a good idea to consider this when determining what height you will build flood-resilient strategies to.

Flood resilience strategies for architects, engineers and trade contractors

Now that you and your client have determined the estimated flood height of the property, you can start to determine which strategies will suit the property’s flood resilience needs and the client’s brief and budget.

A flood resilience architect and his client with their backs turned to the camera, crouching inspecting flood resilient skirting of a house under construction.

Choosing flood resilient strategies

When working on a flood-prone property, you can adapt what you are currently doing to introduce the best flood-resilient techniques into your work.

Watch this video to learn techniques that will build flood resilience into your clients’ properties:

https://vimeo.com/565879608

Quick flood-resilient tips

There is a range of simple and complex flood resilience techniques that you can adopt for your client.

Use water-resistant external wall materials and cladding

Builder inspecting hardwood external cladding of a house being constructed

Use water-resistant flooring and skirting

Builder installing tiles as skirting to above the estimated flood level

Use first stair riser to avoid cavities

Image of wooden stair with the first vertical panel popped out to make cavity underneath accessible for water to escape.

See below for some quick tips to build flood resilience in your home.

Decide if materials need to be water-resistant or waterproof

Receiving information from your clients and their FloodWise Property Report about how long the property can be inundated with water will help you make decisions about which materials to use. If the property is likely to only experience short inundations of water (a few hours or less) then using water-resistant materials, such as hardwood, may be appropriate. Whereas, if the property is likely to experience long inundations of water (multiple hours, or even days), then using waterproof materials, such as tiles, may be appropriate.

Look out for cavities

Think about any cavities in the building design that can lead to a build-up of water. For example, if the property has a closed staircase, replace with an open staircase design or install a first-stair riser to let water out.

Treat every room like a wet-room

Treating every surface of the property below the estimated flood height as a ‘wet-room’ will help ensure that all materials are resistant to a flooding event and won’t lead to leakage, moisture or drainage issues.

Use resilient materials for internal walls

Use resilient materials like fibre cement sheeting instead of plasterboard, and use moisture-resistant insulation, such as rigid foam insulation. If there are internal cavities in the walls that can’t be filled with water-resistant materials, ensure there is ventilation to allow air flow in the space to avoid moisture and mould build-up.

Use resilient materials for external walls

Use water-resilient materials for the external wall structure (such as brick-work) and replace non-resistant cladding (such as weatherboard) with resistant cladding, such as rendered fibre cement composite or hardwood for properties with an expected short-duration of water inundation.

Use resilient materials for flooring and skirting

Replace carpet with easy-to-clean flooring solutions such as tiles or polished concrete. Install water-resistant skirting (like stainless steel or tiles) above the estimated flood level.

More flood resilience strategies

View the interactive window below to see how a variety of flood-resilient design strategies are used in a Brisbane house:

Click the links below for more flood resilience design strategies:

Full list of all flood resilient design strategies

Showcase of different strategies used in Brisbane homes

Become a contractor for our Flood Resilience Programs

Brisbane Sustainability Agency engages with the building, trade, engineering and architectural design industry to provide resilience assessments, recommendations and works for a range of Flood Resilient Suburbs Programs.

If you’re interested in improving your expertise in highly-demanded flood-resilient building and construction and would like to work with Council to build a manageable stream of consistent and challenging work, please get in touch with Brisbane Sustainability Agency at floodwise@sustainablebrisbane.com.au about becoming a contractor for our Flood Resilient Suburbs Programs.

More information

You can learn more information about flood-resilience strategies in this comprehensive Flood-Resilient Building Guide. Alternatively, read the many recommended techniques that have already been used in the pilot Flood Resilient Homes Program here: Flood-resilience strategies.

If you have more questions about flood resilience, contact Brisbane Sustainability Agency at floodwise@sustainablebrisbane.com.au

Interested in flood resilience but for your own property or business?

View more tips on how to build flood resilience if you represent an apartment building body corporate, own a house, or a business.

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