Repair After Flooding
After a flood has occurred, many things need to be established prior to remedial works taking place. Firstly, what caused the flood? For example, the way in which you approach remedial works will be different depending on whether the flood was caused by a failed sewage system, or was due to a river overflowing. The possibility that the water may have come from more than one source will also need to be considered.
Potential future flood frequency, expected flood depth and expected flood duration should be determined for the property and should inform the level of repair. Information on flood risk is available from https://www.gov.uk/check-flood-risk. Flood surveys can also be carried out by a qualified surveyor. Where there is a significant risk of future flooding, then the standards of repair will suggest improving the resilience or resistance of the building.
How Does Flood Water Enter a Building?
Flood water will always follow a path of least resistance and will enter a building at the weakest points in the construction, particularly through masonry and construction joints, and any voids and gaps. When designing a flood repair solution, it is important to consider all the various points of entry into a structure including porous masonry, construction defects, floors, service penetrations (e.g. utility pipes or cables), ventilation ducts, windows and doors.
Flood Resilience and Resistance
Flood Resilience Systems
Also known as a ‘water entry strategy’, flood resilience systems allow water to enter the building but use materials that will not be damaged by floodwater or materials that can be easily repaired or replaced. This is considered a robust strategy as it is not always possible to completely stop floodwater from entering a property. According to UK guidelines, any design must let water enter the building above 0.6 m floodwater depth to avoid placing too much pressure on the structure.
Flood Resistance Systems
Also known as a ‘water exclusion strategy’, flood resistance systems use low permeability materials to keep floodwater out of a building. They cannot be employed for floodwaters above 0.6 m depth due to structural concerns but can significantly reduce the impact that flood events have on the lives of building occupants. However, an effective flood resistance system can be hard to achieve due to the extreme diligence and attention to detail required at both the design and application stages.