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Preparing for a flood if it's forecast

When floods are forecast, there are several essential steps heritage property owners/land managers should take to prepare and respond effectively:

  • Monitor emergency agencies flood warning classifications is crucial (minor, moderate and major tiers).
  • Gather essential items, creating a flood kit,
  • Have an emergency plan readily available are vital components of flood preparedness.

During a flood

When a building is being flooded, it’s essential to prioritise safety and minimise damage.

  • If it is safe to do so, turn off gas, electricity, and water supplies
  • Do not to touch sources of electricity while standing in floodwater, as this poses a severe electrocution risk.
  • No one should enter the heritage building until flood waters have receded and you have been told it is safe to do so.

By following these steps and being prepared, heritage property owners can better protect themselves and their properties during a flood, reducing potential risks and damage.

Recovery guidance (for after the event)

Managing recovery is a critical part of handling emergencies.

It involves various aspects like:

  • Fixing infrastructure
  • Restoring the environment
  • Stabilising the economy and ensuring the well-being of communities

Recovery offers a chance to improve these areas, making communities more resilient.

Community-focused recovery is essential because disasters have a significant impact on people's lives and helping communities in their recovery is a complex task. Every community is unique, with its own history, values, and challenges.

Dealing with flood damage

When floodwater enters a building, it usually causes some level of damage, which requires cleaning, drying, and repairs.

The extent of damage can depend on:

  • The water's depth, speed, path, how long it stays inside the building
  • Building materials, contaminants in the floodwater
  • How quickly the drying process begins

Minor damage

Shallow flooding, which doesn't rise above the floor level, usually results in minor issues. However, even if water didn't enter your heritage property during the flood, underground areas like cellars and basements might still be affected and should not be overlooked during post-event checks.

Major damage

More significant damage occurs when floodwater rises above the floor level, affecting internal finishes, electrical systems, furnishings, personal belongings, and even the building's structure.

Insurance and challenges

Sometimes, the recommended actions for flood damage repair from insurance companies and contractors can harm historical buildings and breach heritage laws. For example, unauthorised removal of wet timber panelling or floors and lime plaster removal from walls.

When in doubt, contact Heritage Victoria to talk to a heritage consultant before you agree to any flood recovery work – this can help ensure compliance with heritage regulations.

It's crucial that a heritage consultant assesses what is significant in an older building and what can and should be preserved or restored. Contractors or consultants with no heritage experience can inadvertently damage historic structures, leading to significant harm.

Damaged building materials

Historic building materials can deteriorate during floods and require appropriate treatment. These materials include:

  • Masonry (stone and brick) walls
  • Timber frames
  • Timber cladding
  • Concrete
  • Earthen walls and floors
  • Lime-plaster walls and ceilings
  • Various decorative internal and external finishes.

Impacts on timber

Organic materials like timber can swell, distort, and suffer from fungal and insect infestations when wet. If they dry too quickly or at high temperatures, they may even shrink, split, or twist. Inorganic porous materials are generally less susceptible to biological attacks but can experience significant damage if salts and water crystals within them are released through improper drying or in very cold conditions.

Impacts on walls, floors and mortar joints

After the building and surrounding land has dried out monitor the stability of walls, floors, and mortar joints. Investigate any cracks that appear in foundation walls or around openings. Cracks due to temporary factors like clay soil expansion should shrink or stop expanding as soil moisture returns to normal. However, cracks caused by foundation erosion may worsen over time as the building settles, indicating structural instability that requires examination by a structural engineer.

Regular inspections of under-floor timbers are crucial, especially six months after flooding and then annually, to detect evidence of biodeterioration and rot.

Archaeological sites

Archaeological sites are impacted in different ways:

  • Intense flooding can directly damage and displace structures and artefacts
  • Changes in rainfall can result in prolonged saturation, increased water erosion, or drying and cracking of soils, all impacting archaeological deposits and material integrity
  • Floodwaters, debris, and sediments can damage buried deposits, exposing previously buried archaeological materials and causing the loss of overlying deposits, ultimately impacting their integrity

Risk to structural damage after a floor after a flood (during a drying period)

Water erosion and soil movement can crack and impact the stability of earlier structures and artefact locations or even collapse structures.
Drying conditions affect materials like wood, brick, and metal in various ways. This can lead to structural damage, artefact exposure or burial, potential inundation and loss, and destruction of structures.

Recommended action to safeguard sites in the face of flooding threats includes:

  • Increase monitoring efforts to stay on top of any emerging risks (e.g., loss, collapse, or public safety concerns etc).
  • Establish a comprehensive plan that covers recording, excavation, and off-site preservation in situations where the risk becomes unacceptable and it's feasible to do so.
  • Consider a retreat strategy (if necessary) that involves site documentation and, in consultation with the local community, either accepting the loss of the site or relocating it to a safer location.

Page last updated: 10/07/24