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Floods and heritage - technical notes

Following the October 2022 floods, technical notes were prepared by a panel of heritage specialists in:

  • structural engineering
  • mould and materials conservation
  • collections/objects
  • building
  • architecture rising damp and salt attack

Heritage Victoria would like to thank RBA architects, Kyi Conservation, David Young, Ingegnaria Consultants and Period Building Conservation for collaborating with Heritage Victoria in response to the 2022 Victorian Floods. The following guidance and the series of “Floods and Heritage” technical notes have been produced with their help.

The following technical notes are aimed at helping:

  • Land managers, owners, and heritage professionals better understand how to prepare for, respond to, and recover from flood events by learning from past experiences.
  • Prevent hasty, damaging treatments, ensuring that our heritage places can be enjoyed by future generations

Each technical note includes strategies or actions you can take across the various disaster management stages.

Each note is on a stand-alone topic but may reference other notes in the series where issues are inter-related. We've also included a glossary of terms to help you understand specific terminology used.

Technical notes

The technical notes provided are for download and printing to help you. If you require an alternative format please get in touch with us.

Glossary of terms

Buoyancy

Floodwaters can produce enough force to make lightweight buildings (eg. weatherboard clad buildings) that are watertight, to float, especially when not attached to their piers or stumps.

Colourwash

A coloured weatherproof finish to lime coatings and masonry substrates. Refer to limewash.

Data loggers

Data loggers are used to monitor the key parameters of temperature and relative humidity (RH), providing an insight into the environment of a space/building and the relationship with its surrounds. Undertaking environmental monitoring during the prevention phase of a Disaster Risk Cycle is strongly recommended. Dataloggers are relatively inexpensive (approximately $300/unit) for temperature and RH, and are easy to use, with Bluetooth pairing connecting to a phone/tablet app for downloading the data. These are suitable for the level of environmental monitoring required for buildings

Earthen berms

Similar to a levee bank, that is a raised barrier composed of earth. Berms would be more permanent than levee banks and would assist in preventing stormwater runoff or floodwaters from entering a sensitive area or direct the water to drainage away from buildings.

Footings

Footings are the structural element built in the ground at the base of the building that the building walls are built on. Generally small scale heritage buildings are founded on shallow and low stiffness bluestone or rubble footings. From early in the 20th century, heritage buildings started to be built on concrete strip footings which again for small scale buildings were shallow and of low stiffness.

Foundations

Foundations referred above as founding soils, are the soils the buildings footings are seated on.

Hydrostatic pressure

The weight of flood water on foundations externally or underneath the floor and pushing upwards.

Limewash

A thin protective outer layer to lime coatings and masonry substrate, protecting the surfaces of new lime renders.

Relative humidity

The amount of water vapour in a set volume of air, relative to the amount it could hold at a specific temperature and pressure. In general, moisture moves into or out of materials in response to the relative humidity. When the relative humidity of the air is high, moisture is more likely to move into materials. When the relative humidity of the air is low, moisture is more likely move out of materials.
Render - Generally, traditional renders consist of three materials – cement, lime and sand. These are mixed in differing percentages and applied in three coats – a bonding coat (adheres to the substrate, contains cement), strengthening coat, finishing coat (no cement).

Skim coat

Finishing coat to render, generally a limewash or colourwash.

Soil reactivity

Reactivity of soils refers to the volume change that occurs in these soils as their moisture content changes – that is reactive soils shrink when they dry and swell when they wet. The different level of reactivity refers to the amount of volume change. Typical reactivities include Extremely Reactive, Highly Reactive, Moderately Reactive and Slightly Reactive and refer to soils which may experience extreme, high, moderate and slight ground movements from moisture changes.

Superstructure

The super structure refers to the collection of all building elements built on the footings, walls, floors and roofs.

Swale

A wide but shallow drain or channel with sloping sides designed to redirect rainwater (stormwater, floodwater).

Page last updated: 10/07/24