Preparing for a flood

Prevention and preparation  ​

Preparing your heritage asset will improve capacity to recover in a timely manner and, in some cases, lessen the impact. ​

Doing preparation in the dry times will give you the best chance to be able to respond during an event. This will help:​

• Minimise impact​
• Reduce financial costs incurred by individuals, owners, land managers, and the public during post-flood clean-up​

Understanding your historic building is critical for prevention, preparation, response and recovery: ​

• When implementing flood protection measures for historic buildings, sensitivity to their unique characteristics and significance is essential. ​
• The goal is to preserve and respect the existing structure and materials. ​

​Flood protection measures come in two primary forms: ​

• Flood-resistance or proofing works, which aim to reduce the amount of water entering a property​
• Flood-resilient works, which aim to minimise damage when water enters

Disaster management for floods

This section will help land managers or owners to:

• Understand what it means to prepare, prevent, respond, and recover from floods.
• Get practical advice that will help you to achieve better heritage outcomes.

In terms of flooding, there are four stages that need to be considered:

• Preparedness (before an event)  - assessing, understanding, and managing the risk.
• Prevention (when a flood is imminent) – immediate actions to prevent damage, like sandbagging.
• Response (during an event)– coping with the flooding while in progress.
• Recovery (after and event)– limiting damage after flooding.

The series of floods and heritage technical notes provide further detail on specific topics.

Maintenance

The most effective action to help you prepare is doing regular maintenance. Keeping your buildings and site in sound condition has hidden benefits when faced with an imminent flood.

If you have maintained the property appropriately, you won’t need to be playing catch-up and will be able to concentrate on other big flood related tasks.

Examples of maintenance tasks are as follows:

Roofing

• Clearing gutters, rainwater heads, downpipes and ensuring stormwater drains flow will assist to get the water off your building quickly. Blocked gutters (or gutters falling the wrong way) and blocked rainwater goods will result in water backing up and entering the roof space and consequently the wall structure and ceilings.
• Check that roof coverings are sound, slates are not missing or shifting, iron sheets are not missing or rusted, and flashings and cappings are secure. Go to flood management of roof and rainwater goods for more information.
• View flood management of roof and rainwater goods.

Wall structures

• Moisture rising in masonry walls drawing ground salts. View looking after flood affected masonry.

Flooring

• If your building has timber floors, make sure sub-floor vents on exterior walls are clear of site soils, above paving levels and intact. View building footings for more information.

On the ground and/or adjacent sites

• Water overflowing onto the ground saturating already wet soils and backing up into the spaces under the floors.Adjacent site conditions:
  • garden beds are away from side of building to prevent excess watering on walls and foundation soils
  • site levels and adjacent paving fall away from buildings
    trees placed where root systems do not impact building footings or soil conditions
  • ground and stormwater drains are free flowing away from buildings.

Assessing and managing risk

The disaster preparedness toolkit has an easy-to-follow worksheet which shows you how do a risk assessment for your heritage asset. It will help identify the factors that keep your heritage asset safe or put it at risk.

Ask yourself the following questions:

• Are you in a hollow, at the bottom of a rise or hill, adjacent to a river/creek, between two rivers?
• Is there a history of flooding in this area?
• Is the landscape flat – water will travel long distances on flat ground finding its natural level?
• Is my roof sound and will the stormwater elements (gutters, downpipes, stormwater and site drains) be capable of taking heavy rainfall off and away from the building?
• Are the sub-floor vents clear and capable of allowing water to pass through the building in the area under the floors?
• Is electric wiring in a vulnerable location – at risk of water getting in and causing major costs in recovery?
• What are the identified heritage values for my heritage listed place/object (VHR, Local Government HO) and, if they are at risk, how may you protect those values?

By implementing these strategies, you (heritage asset owners and land managers) can significantly reduce the impact of flooding while ensuring the preservation of their architectural and historical significance.

Learn more about heritage disaster and risk management as a process.

Using support networks and communications

Strategies for assisting you, your neighbours and broader communities to be more resilient during events such as floods include the following:

• Stay aware of any communications coming from the Victorian State Emergency Services (VICSES). VICSES is the control agency for flood response and coordinates flood warning systems (VIC Emergency Application), emergency plans guidance, local flood guides and sandbagging guides.
• Follow your local community social media groups or threads as this can be a great place to find frequently updated information about what is happening around you
• Consider setting up a phone tree – while the relevant authorities will initiate a phone tree for their operations, private owners can do the same for your own use. Think about the hierarchy of who needs to be contacted first and prioritise from there. 
  Set up an emergency event directory with retreat safety zones for your area identified with a map, key contacts, procedures, and tasks identified.

Preparation for protecting heritage property against flood

When it comes to dealing with the possibility of your heritage property flooding, there are two main approaches – wet proofing and dry proofing.

Deciding which strategy to use for potential future floods is an important decision that should be made considering the specific circumstances and risks involved at your heritage property.

Wet proofing (flood resilience):

• Involves working with the water rather than trying to keep it out entirely. This approach can still present some level of risk to property.
• To make your building more flood-resilient, flood vents can be installed in walls or doors, about 300mm above ground level. These vents allow water to enter and exit your building at the same rate as the external water level, reducing the strain on your building's structure.
• When you anticipate flooding, it's crucial to move utilities and electrical appliances above the expected flood level, preferably to a second floor. If your building has a basement, you can use a pump to remove floodwater, but be cautious as rapid pumping on saturated soil can cause structural damage.

Dry proofing (flood resistance)

This involves sealing your building to keep floodwater out. While it does a good job of protecting your space, it can sometimes push water onto neighbouring properties.

To prepare for potential flooding, you can use temporary barriers like:

• Laying sandbags or plastic sheets to prevent water from entering your building, depending on how high you expect the floodwaters to rise.
• Constructing a temporary levee bank but be aware that this can also trap water inside, prolonging the flooding (masters hut).
• Creating drainage ditches, swales, or earthen berms made of natural materials to divert water away from your building.
• For low-level floods, flood doors are an option, but deeper floods can exert significant force on your building, potentially causing foundation issues. 
  Air vent covers can keep floodwater out for a limited time.
• To prevent sewage and stormwater from entering your building, consider adding backflow valves to your plumbing.

Resources for preparing for floods

Resources to help with recovery after a flood

Page last updated: 10/07/24