Flood repair and remediation

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.

It should be quickly established if any contamination may have occurred, as this will strongly effect how the whole flood remediation process is handled. It should be noted that although flood water may not contain contaminants from its source, it may have picked up contaminating materials during the flood period. Possible sources of contamination include:

• Black / Grey Water
• Oil / Other Chemical Contamination
• Sea Water
• Biological (e.g. Sewage)
• Silt, Salt, Sand / Other Fines

We strongly suggest that any materials affected by the flood are sanitised prior to removal.

Where buildings have been subjected to flood water above 0.6 m in height, or if there is evidence of movement or cracking of structural elements, a structural engineer should be consulted before any further works take place.

Knowing the building makeup and history is central in establishing the methods and considerations the flood repair team will need to take. If the building has been flooded before, several repairs may have already taken place and problems with contaminants may already be an issue. Materials during the construction of the buildings (and in subsequent repairs and modification) will need to be identified, as they may have an effect on the way the building dries out. All of these factors will affect how which system (or systems) can be used to repair the building and offer it future protection.

Sanitising, Stripping, and Drying

Prior to any flood remediation work being carried out it will be necessary to sanitise the flood-affected building using a suitable biocide. In most flood situations bacteria will have entered the building in the flood water, particularly in floods where sewers have backed up.

Once the area has been sanitised, all affected fixtures, fittings, floor coverings, and plasters / decorative surfaces will need to be removed and disposed of in accordance with local regulations. Once this process has taken place, the building should be sanitised again. Any materials which may hinder the drying out process (e.g. impervious floor coverings) should be assessed an removed if necessary – followed by further sanitisation.

The aim of drying out of the property should be seen as only removing the moisture that was introduced by the flood and not to eradicate other damp problems that may have already been prevalent e.g. rising damp or penetrating damp. These issues (if present) should be dealt with during the remediation stage or once the property has been re-inhabited.

The house may be considered dry once it has reached the stage at which no further deterioration to the structure or its elements is expected. It is at this stage that a full survey needs to be carried out to establish what needs to be done to return the property to use as soon as possible.

Flood Remediation to Walls and Floors

Oldroyd cavity drainage membranes offer a fast and practical solution for flood remediation of walls and floors. Because they allow the passage of water vapour behind the membrane they can be installed before the walls and floor have fully dried out – greatly speeding up the time it takes to reoccupy a flood affected building. Typically Oldroyd Xv Clear or Oldroyd Xp Plaster Membrane are used on flood-affected walls and Oldroyd Xv Clear and Oldroyd Xs are used on flood-affected floors.

Tanking of contaminated walls using Vandex BB75 or Vandex Unimortar 1 might also be considered.

Alternative products for waterproofing affected floor slabs include Drybase Liquid-Applied DPM, Vandex Super, and ECS Epoxy.

Other Flood Remediation Measures

All timbers should be assessed for timber decay (see our dry rot section). Damp timbers and masonry may have to be treated with timber treatments and masonry sterilants to prevent the spread of timber decay during the drying out period.

In some situations (e.g. where flood water has introduced salt contamination into a wall without a DPC) it may be necessary to inject a new DPC. Dryzone Damp-Proofing Cream offers an excellent solution as it has passed independent tests demonstrating its effectiveness in highly saturated walls (up to 95% saturation).

Improving Flood Resistance and Resilience

If a flood affected building is thought to be at risk of flooding again in the future, consideration should be made to improving its flood resistance and or flood resilience. See our flood resistance and resilience page for more details.

Further Information

If your property has been affected by flooding, or if you would like information on improving your property’s capacity to deal with a flood, please contact our technical department on 01403 210204 or submit an enquiry.