As building on flood plains continues to be an uncomfortable necessity, James Parker reports on a project to develop a house prototype that rises and falls as and when a flood occurs, thereby unlocking previously unviable sites across the UK.

Spiralling UK housing demand, coupled with the shortage of available land and exponential climate change, presents a thorny problem leading to an equally uncomfortable conclusion. The current 300,000 homes per year target means that the industry needs to continue to build on flood plains. The increased likelihood of serious flood events in coming years means that high water levels must either be grappled with by developers and their customers, or sites will remain unbuilt.

Floods are of course hugely disruptive and damaging – the Environment Agency says that the average time for a family to return to a home after it is flooded is over nine months, disrupting work, schooling and mental health, and causing millions of pounds of insurance claims nationwide. The average cost of flood damage to homeowners is £30,000. However, the Government currently remains committed to its new homes numbers, and the risk of homes flooding, despite SuDS and flood resilience measures, is made more likely by those developments on flood plains.

Currently, one in six existing homes have been built in what is now a ‘flood risk area’ – a total of 2.4 million homes. However, a further three million are at risk of surface water flooding, exacerbated by climate change. Perhaps most concerning, 27% of all new homes (60,000 per annum) are currently being built on a flood plain.

With housing developers having to look “further and wider” to meet demands – not least from home buyers wanting to live in certain areas – this sometimes means “venturing into less than ideal land,” as light gauge steel frame manufacturer Hadley puts it. With millions of homes at risk and millions being spent on temporary flood prevention, the company is proposing a more permanent solution in the form of its FloodSAFE House concept.

SAFE AS HOUSES 

Currently under testing in a giant water tank at HR Wallingford – the largest ‘wet’ water testing facility in Europe – the FloodSAFE House concept is proving its inventors’ claims of being a practical solution to avoid damage to a property. Based on an adapted Hadley light gauge steel frame, the three-bedroom (although roofless) replica detached home has been developed in partnership with Floodjack International, inventors of a mechanical steel jacking system purpose-designed for raising buildings in flood emergencies. 

Now a fully-functioning test prototype, the process will result in a Flood Protection Certificate before it sees a ‘live’ test with occupants to see how it performs as a home. Part of what enables this model to be easily lifted by the Floodjack is that while a traditionally built three-bed house weighs between 120-150 tonnes, Hadley’s brick slip-clad model is currently down around the 40 tonne mark.

The system is driven by sensors in, around and beneath the building, which activate the jacks to steadily lift the lightweight structure – at the same speed as the flood waters rise – and lower it gently once they have subsided. According to the project team, it will “keep contents safe and dry at precisely the moment it is needed,” therefore reducing both damage to the fabric, and the time needed for people to return home following a flood. 

The Environment Agency-approved water sensors will trigger a control panel within 15 seconds of detecting a “significant water-related event.” The house takes 15 minutes to reach its full 1.5 metre height  – UK floods are typically 500 mm, according to consultant WSP who are working with Hadley and the University of Liverpool to develop the system. WSP has liaised with both the Environment Agency and insurers to “help them understand how the house would work and what the implications would be for them.” They have also spoken to local authorities and housing associations about the ways in which the FloodSAFE House “could open up previously unsuitable sites for social housing development.”

The system’s control panel sits unobtrusively beneath the ground floor, and keeps the structure at its elevated level until “it is safe for the structure to return to ground level,” says Hadley. If any obstructions are detected, the jacks will automatically stop. As well as the steel frame, the house consists of offsite-constructed SIPS (structural insulated panels) modules, which are all shipped to site in a single day, and which offer sustainability benefits over traditional home construction, according to Hadley. 

INDUSTRY PIONEERS

Ben Towe, group MD at the Hadley Group, explained at the demonstration event why the steel frame company has jumped wholeheartedly into the initiative. It’s partly a commercial imperative; the commensurate potential numbers of homes which could be created in previously unviable sites give it “opportunity to achieve scale in the housing market.” 

“It’s not just about what you build, it’s how fast,” he says. With the highly accurate, as well as rapid ‘Advanced Methods of Construction’ approach it is using to create offsite buildings, “we could steal a bit of a march against the rest of the world” with the FloodSAFE House, he believes.

“Ultimately, the opportunity for us and developers is huge, because you can put more houses on the same site, which can make each site stack up commercially.” This is reportedly leading to large amounts of interest among housing developers already. Towe told Housebuilder and Developer, “If you have a solution like this in your back pocket,” (as a result of being able to build out more of a site), “you can potentially bid more on the land, and be more competitive.” This can also mean being able to build a higher value house or houses with an unobstructed view of countryside, potentially more than offsetting the increased investment of including the FloodSAFE system. Currently unviable developments (e.g. of 50-100 homes) might be able to achieve an extra 20 units, therefore making them a commercially realistic prospect.

He says that with occupants being able to stay in their homes for “two or three days” in a major flood (depending on utilities being working etc), the system also gives first responders a considerably wider window in which to operate. “The opportunity is not just to build things, it’s to give people in them a better quality of life.” Towe concluded however by wondering why housing has been the only sector that hasn’t embraced such advanced offsite concepts yet – “it’s been a real journey to understand it, but we are now seeing exponential growth.”

At an event where the prototype house was demonstrated slowly rising above a giant water tank at HM Wallingford, Andrew Parker, founder of Floodjack International, explained how the University of Liverpool was keen to collaborate, in order to gain detailed data from the various sensors placed around the house to assist with its research. 

The university researchers have created a Digital Twin of the house which will be able to take the data from the prototype and incorporate it in their model to see how the structure behaves, and feed back into the project to see where the testing parameters might need tweaking.

An ex-builder Parker developed the straightforward Floodjack system following the 2007 floods, when a friend’s family were uprooted from their home, with worse to come in 2009 when he had another, this time uninsured flood, devastating the family finances. He explains there is a ‘social value’ element to investing in a new, low-cost solution, and is particularly keen to target it at local authorities: “Most of the people affected by flooding are underprivileged, and have no choice of where to live.” 

He said that 300 local authorities were forced to still build in flood zones with “little to no flood defences,” and said that the FloodSAFE project offered the chance to “put the accountability on the developer, and take the responsibility away from the local authorities.” It enables them to offer “affordable, practical properties which are safe for the property and the people who live in them.”

Simon Gilliland, associate at WSP, reckons that the time is right for a solution like this, given that there is “no silver bullet for flood risk management, particularly in light of the impact of climate change. He stresses: “We need to think holistically and harness new approaches like the FloodSAFE House.”

The project’s instigators believe that the system offers a far more reliable solution than building “ever higher defences,” which even the Environment Agency admits will not be a long-term answer. It is also less expensive than installing resilience measures which need time before occupants can reenter the property after floods. According to a recent report, the FloodSAFE House instead provides a ‘social value forecast’ of a “£2 return for every £1 spent,” partly also because occupants would generally be able to remain in their houses for longer during a flood. They also believe such an innovation should enable insurance companies to offer a reduction in premiums for new homes in flood zones, which doesn’t exist currently.

Simon Gilliland says that the concept also has a wide potential application internationally, with 29% of the world living in flood plains. The house “unlocks so many opportunities” for planners, he says. And, against other more costly, carbon intensive mitigation measures, it’s a “low carbon, future-oriented development solution.” Taking a house completely out of the water, the system shifts the paradigm away from resilience or mitigation to “complete flood avoidance.” In this way, he believes it is “one of a kind.”

CONCLUSION

The next stage of the project is a test planned at Wirral Waters in conjunction with developer Peel L&P, which will see the team construct – and flood – a house in a somewhat less controllable ‘real world’ environment than the indoor test provides. The design forms part of a wider bid by Merseyside Strategic Flood and Coastal Erosion Risk Management Partnership to an innovation programme by the Environment Agency, focusing on how smart technology and data analysis could reduce the impact of flooding in the area. 

As we approach another winter flooding season, it’s inevitable that as the climate warms, we will see more serious flood events, causing untold misery for communities already crippled by a cost of living crisis. While housing developers remain forced to build on unsuitable flood plains, a pragmatic, although unusual solution such as this may be the necessary way forward. Hadley certainly thinks so, and is also confident that Defra is keen to give its support to the approach.