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Flood Resistance and/or Recoverability

Ed Barsley

Founder of ‘The Environmental Design Studio’ and ‘Hazard + Hope’ and author of ‘Retrofitting for Flood Resilience: A Guide to Building & Community Design’

The Code of Practice for Property Flood Resilience (CoP) highlights a range of ways in which properties can be made flood ‘resistant’ and/or flood ‘recoverable’, but the distinction between these two approaches to Property Flood Resilience (PFR) is important to note.

‘Flood Resistance’ is defined in the CoP as being, ‘the use of materials and approaches to manage water entry into the property.’ This approach is centred around excluding water entry and that could be through the use of measures such as flood doors or deployable flood barriers. However, whilst resistance-based approaches can be incredibly effective in helping to prevent and slow the rate at which flood water enters a building, they aren’t necessarily suited for every construction type or flood risk context. Added to that, their performance is of course reliant on them being correctly specified, installed, managed and maintained over time.

So, while resistance measures are intended to keep flood water out of buildings, the CoP defines a ‘Flood Recoverable’ approach as being, ‘the use of materials, products and construction methods that prevent the internal fabric of the property from being unduly damaged by floodwater and allow it to recover quickly after a flooding.’ This approach really focuses on minimising the impacts flood water can cause, if and when it comes within a building. It could for example include replacing or specifying internal wall / floor finishes with materials which won’t swell or distort when in contact with flood water. However, even with a recoverable approach in place, after a flood there can still be a need for drying, decontamination and the replacement of affected items. But crucially, recovery may not require a significant rip out and reinstatement of the building’s fabric and its contents, and that can mean a far less lengthy, costly and stressful process.

Alongside flood ‘resistance’ and ‘recoverable’ strategies, it’s important to note that there are also avoidance-based approaches for PFR. These can include raising floor levels, changing the location of habitable areas or even adjusting the vertical or horizontal position of the building itself to reduce the overall ‘exposure’ of the property to flood risk.

So which approach should we use?! Well, following the stages and steps set out in the CoP can help to determine the flood risk context, the site/property setup and suitability of particular PFR approaches and this applies to both new build as well as existing developments. You would for example, not necessarily expect a new build property to have to be reliant on flood resistance measures from day one to keep the building safe and dry. If that were the case it could well be that key thresholds, the position of habitable areas, or location of the property itself has not been thoroughly considered. It does of course depend on the context, and given that the frequency and severity of flood events is increasing as a result of climate change, the inclusion of flood resistance and/or recoverable measures to help ensure a development is future proof, can be very apt.

In the end though, it doesn’t have to be a ‘one or the other’ choice when it comes to considering flood resistance or recoverable approaches for PFR. They can be complimentary approaches and used conjunction to great effect to provide a diverse range of resilience measures that can help weather any storm, or should I say flood.