With the available sites for new houses dwindling, building on flood plains looks more likely. But can we safely build new homes on flood-prone areas and how should the construction sector react to increased demand for new flood-resistant homes? Dave Howell reports.

The changing climate is expected to result in more extreme weather events. The UK has already suffered high levels of flooding. Around 16,000 homes were affected by Storm Desmond in 2016. With current estimates stating that one in six homes in the country faces a flood risk, coupled with the continued pressure to build more homes, and a declining supply of available land, can developers safely build on the flood plain over the long term?

The current strategy for building new homes is covered by the National Flood and Coastal Erosion Risk Management Strategy for England, which sets the policy framework for managing vulnerability of flooding. For developers, proposed new or replacement homes that fall into Flood Zones 2 and 3 need a full risk assessment, which forms part of their planning application. This ensures the properties have the appropriate level of flood protection.

Says Andy Stanford, Director for Leading Structural and Civil Engineers Walsh: “Should we build on areas which flood regularly? Almost certainly not. Should we build on areas which flood once every 50–100 years? No reason why not but mitigation should be provided. Should we build on areas which flood say once in a millennium? Of course, unless it is highly sensitive, eg a nuclear power plant. We also need to consider what we build: a boatyard? Of course. An office? Maybe. A hospital or old people’s home occupied by the vulnerable? Of course not.”

Building on the flood plain has been the norm in other counties prone to flooding, most notably the Netherlands, where a third of the county is below sea level. Indeed, the recently completed development at Ijburg where 18,000 homes are built on artificial islands illustrates how far technology could help developers find innovative ways to build on land with a high flood risk.

More thorough planning applications for homes on floodplain is clearly needed to ensure proper risk assessments have been made, and additional innovations in construction will be made to mitigate any potential flood risk. Building on the flood plain seems inevitable, and figures suggest that last year alone 20,000 new homes were built on flood plains.

Amphibious homes

The approach that developers and their supporting services take with the construction of new homes continues. Tim Wolfe-Murray, Partner at Clague Architects gives an insight into how building on flood plains must form part of an integrated plan for housing over the next decade.

In your view will the UK have no choice to keep building on the flood plain?

“We have been told that as a country we need to be building 240,000 new homes per year. The issue is that there is a lack of space for these buildings to be built. There are just not enough deliverable brownfield sites in urban areas, while more and more land is being protected as green ‘buffer’ space around existing settlements. Meanwhile flood plains are being ignored as potential sites for developments. It is time to reassess.”

Are there viable alternatives to building on flood plains?

“Obviously if there are alternatives to building on floodplains, then they should be explored. However, where are we going to find such sites? Instead we need to look at what we already have. Recently it was reported that there were almost 200,000 empty houses in the UK. Many of these are farmhouses which are ripe for redevelopment. By breathing life into these empty premises, we could have a potential answer for the housing crisis.”

Can technology help us build homes on flood plains without the risk of actual flooding occurring?

“Clague Architects has recently had planning approved for a development in Deal, Kent. The living accommodation of these modern town houses is to be on the first floor, while the ground floors are given over to garages and storage. These are less vulnerable to water damage, and incorporate flood-resilient/resistant construction.”

What can the UK learn from other countries about building flood resistant homes in flood risk areas?

“We must start thinking outside the box and not write off developable land just because of the technical constraints. If anything, this gives architects and the construction industry a real opportunity to think innovatively and really show off what they can do. With greater creative input from architects and building specialists, these solutions could very well be the answer to the housing crisis. By being at the forefront of future designs and technologies, we can ensure sensible and safe development on previously ‘at-risk’ areas.”

The question whether we should build on floodplain remains, but many in the construction industry state that there is little choice if green belt land is to remain off limits.

Ashleigh Gay, Sustainability Consultant at Radley Yeldar, concludes: “Creative and innovative solutions to this issue should be encouraged by Government from industry and research institutions. What can the Government do about land swapping? How do we harness the explosion in thought leadership on ‘resilience’ over recent years? How can green infrastructure play a role in adapting our built environment to minimise the damage of flooding? These are some questions we should be exploring.”

An enhanced planning application process and advances in flood protection technologies does mean that floodplain isn’t the high risk it once was. What is clear is that building on floodplain is a component of the construction industry that will remain long into the future. However, a balanced approach needs to be taken evaluating proposed new sites for construction and how any potential flood risk is to be addressed.

 

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