External walls below flood levels must be made of resilient materials. They should have no internal cavity. This means they can dry out afterwards with little effort. This also avoids water traps that could grow mould on surfaces.

Some examples of resilient materials include:

• external single-skinned rendered fibre cement
• hardwood framed fibre cement external wall with extruded polystyrene closed cell insulation
• concrete or core-filled block (no cavity) and
• rendered AAC (autoclaved aerated concrete) wall systems.

If you are retrofitting or repairing your home after a flood, consider replacing cavity walls with single-skin ones. Examples include:

• single-skin stud or brick walls
• solid block walls or
• off-form concrete walls.

You should also replace weatherboard cladding below the flood line with new cement composite cladding. 

Waterproof membranes provide a seamless and flexible waterproof barrier. They will prevent water absorbing during flooding. This reduces drying times. They can also protect timber wall framing and other structures from flood damage.

If structural members are porous and not protected by a waterproof membrane, then floodwater can penetrate them. This can increase the time it takes to dry.

Open stair designs don't have a void or cavity underneath. They should be made from water-resistant materials in new homes

You should consider replacing existing closed stairs with open-design stairs. These should be made from flood-resilient materials in existing homes.

Use open, bolt-fixed removable treads made of water-resistant material. The tread is the horizontal part of a set of stairs – the part you walk on. Bolt-fixed means that the tread is attached with bolts that may be readily removed so they can be easily replaced after a flood.

Stairs should be wide enough to enable furniture and other items to be carried upstairs as part of the preparation for an approaching flood.  It is recommended to have 1 metre clear between balustrades, or wall and balustrade and to have treads at least 280mm wide and risers of no more than 180mm high.

Use solid core doors in houses to limit potential water damage.

Solid core doors are constructed with a solid piece of material. For example, hardwood or engineered wood. This makes them more resistant to water damage. They’re less likely to warp, rot, or develop mould and mildew, even after prolonged exposure to moisture.

Hollow core doors are constructed with a cardboard-like material in the middle. This makes them highly susceptible to water damage during a flood.

If parts of your home have been flooded they need to be completely dried.

It is important to install stud walls with exposed hardwood next to non-habitable spaces. These spaces include carport, garages, etc. by eliminating wall cavities. This helps to prevent mould and fungal attack developing. 

Rendering block walls can provide a durable and waterproof finish. This improves resistance to damage from flood waters. 

Use solid core doors in houses to limit potential water damage.

Solid core doors are constructed with a solid piece of material. For example, hardwood or engineered wood. This makes them more resistant to water damage. They’re less likely to warp, rot, or develop mould and mildew, even after prolonged exposure to moisture.

Hollow core doors are constructed with a cardboard-like material in the middle. This makes them highly susceptible to water damage during a flood.

You can increase the flood resistance of your property by installing corrosion proof fittings.

Door and window hardware include:

• hinges
• handles
• catches
• stays
• fasteners
• locks and
• deadbolts

Manufacturers can produce corrosion-resistant fittings from corrosion-resistant materials. An example of this is stainless steel. You can also enhance normal fittings by applying a protective coating or plating. 

Weep holes in double brick construction allow for ventilation of the cavity between the walls. This can prevent damage from moisture buildup. They are usually spaced evenly at specified intervals.

Flood water will penetrate the wall via the weep holes or through seepage during a flood event.

Additional weep holes installed above the possible flood level will improve the drying process after the flood waters recede. They should be cleaned out regularly.

A recessed or flush threshold in doorways allows you to sweep water, mud and debris out of your house more easily once the flood waters have receded. This makes cleaning the property easier. It may also reduce secondary damage.

Rigid or closed-cell insulation is flood resilient. It helps to fill the gap in a typical cavity wall. Examples include:

• extruded polystyrene,
• thermoset polyisocyanurate (PIR) or,
• phenolic insulation.

Rigid cell and closed cell insulation do not absorb water. They are less prone to water damage and mould compared to loose-fill insulation such as 'batts'.

Creating water resistant walls in your house reduces the risk of damage during a flood. This can include building walls made out of materials like concrete or blockwork, or installing water-resistant linings. These linings can be:

• marine-grade moisture-resistant plywood
• villa board
• fibre cement sheeting.

Make sure there aren't any wall cavities that can trap flood water and extend drying out times.

Flood water can cause extensive damage to internal wall linings made from vulnerable materials such as plasterboard. The water can even get into cavity walls and damage insulation. 

This advice is best to consider when designing your home or doing major renovations.

Sealed floor and wall tiles are more resistant to water than unsealed tiles.

Coatings can provide waterproof barriers and help reduce flood damage. They help seal the concrete. This prevents contaminants from getting into the tile and grouting. Some coatings can also provide antimicrobial protection. 

Plasterboard ceiling linings are susceptible to damage. This includes mould growth caused by high humidity levels after a flood event.

You should consider replacing plasterboard linings with water-resistant materials. You could also remove the linings to create open ceilings.

Floors are the first thing in a house that is affected by even low levels of flooding. Timber flooring may swell or cup, and carpets are particularly vulnerable to water. Some flooring materials and floor coverings, such as polished and sealed concrete or sealed tiles,  are more resistant to damage from flood waters than others.  

Note:

Waterproof flooring may impede drying when placed over timber (plywood). These floors may require special attention to drying and repair or replacement. 

Carpet is relatively inexpensive to replace compared with timber flooring. 

Polished and sealed concrete floors are resistant to fluids, especially water. Coatings can provide waterproof barriers that seal the concrete and prevent contaminants from penetrating the concrete. Some coatings can also provide anti-microbial protection.