Flood – payout – reinstate

Our flooding specialist and contributor to the new Code of Practice for Property Flood Resilience, Ian Paton, discusses the benefits of flood prevention schemes.

Flood – payout – reinstate. Is this a familiar cycle?

Well, there is plenty that can be done, but not without a full understanding of the actual design, flood risk level and a multitude of other factors.

To gather all the required information can involve extensive surveys. It is important to gather all the facts about what is hidden or buried, and it is always that which is not immediately apparent which is most difficult to ascertain. Out of sight out of mind is a certain way to render a flood defence project obsolete.

There is a wide-ranging palette of survey techniques available which must be expertly interpreted. Ground penetrating radar can reveal hidden voids, services or buried culverts; local boreholes monitored remotely can divulge hitherto unknown secrets about the pattern and flow of groundwater as well as important fluctuations in geology and sub strata; CCTV will plumb the depths of drainage pipework, often exposing surprise junctions with long forgotten tributaries; topographic surveys and laser scanning can hint at previous uses and provide clues for further investigations; boroscopes deftly introduced into wall cavities and other voids can determine how well workmen performed that day, or whether they skimped to get home early and left a future problem for others to worry about.

The investigations required to achieve a truly comprehensive flood defence scheme are the domain of experts, and everything must be considered because, if one item is missed out or overlooked, the full cost of a flood defence investment can be for nothing.

So, let’s assume an expert team has been assembled and investigations have been carried out. All the requisite knowledge about the site is there. How do you make sense of all this information and turn it into a cost effective and appropriate flood defence scheme?

Well in some circumstances you can’t defend against the power of water. For some coastal regions flood depth and dynamic forces might mean an engineered solution to resist flood waters would be too expensive, and then a resilient scheme might be best; work with the water and allow the flood to happen, but design to ensure a rapid return to service.

For inland schemes, especially in urban areas where there are combined sewer systems, don’t underestimate the time and cost of the clean-up. Contaminated water will mean that most things it touches will end up in a skip.

In other cases, after a detailed assessment, it may be feasible to defend a site. A scheme to exclude nearly all water – I say nearly because only a new build could seek to exclude all water – with capture and pumping out of the likely rainfall and what does get through would constitute a flood defended site. Such a scheme would comprise many different components, all of which must work together to keep the flood waters out.

A defended site might have elements of barrier walls, both temporary or permanent, specialist gates and doors, adapted existing structures for resistance or altered flow routes, sealed or valved service penetrations, sumps, pumps, attenuation swales, power back up, remote monitoring and automation systems.

The cost of flood defence schemes can be high, but generally pale into insignificance when compared against the cost of reinstatement, loss of trade, business interruption and, in some cases, penalties for loss of supply. A recent £6M factory flood defence scheme provided a fully defended site and a labour force proud of their level of protection, compared to a £60M overall cost of being flooded a second time; money well spent.

Added benefits will often manifest with grant aid, enhanced maintenance, site improvements, staff well-being and reduced insurance premiums. All a flood defence scheme needs to succeed is the right team of experts committed to considering all options and determining the most appropriate and most cost-effective solution, born out of good site information, and client confidence that the design is right.

Most sites will benefit from site specific flood defence schemes, especially when strategic flood defences may not offer the protection required given the influence of climate change.

Industry is largely on its own when it comes to flooding, and confident investment must be better than multiple successive pay outs – or no insurance at all.

This article was prepared for the Chartered Insurance Institute and has previously been published on the website for The Society of Claims Professionals


If you do not wish to receive further communications from us, please email [email protected]. More details on how to opt out can be seen in our Privacy Policy.

Ian Paton

Partner, building surveying


T +44 (0) 7894 461 912
Ian Paton