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Crunching Carbon Debate | Resilient Housing

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Urbanisation is adding to the pressure on the country’s towns and cities to provide adequate housing.

Late last year the government responded by commiting to build 300,000 homes a year by the mid-2020s. According to analysis by charity umbrella body the Wildlife Trusts, that means finding around 9,375ha of land per year, based on recent experience of average housing density.

So, as civil engineering becomes ever more intrinsically linked with the challenge of climate mitigation, adaptation and resilience, how much of this land can be reclaimed from the UK’s flood plains to become new residential development?

And 10 years on from Sir Michael Pitt’s review of the 2007 floods, can his key recommendation that building on flood plains be the “absolute exception” now be overlooked? Because as things stand, few are willing to take this on.

Over-engineering is important

“Planning is important but the doing is something we have to be brave about. That ‘doing’, in some circumstances, has to be over-engineering. I don’t think, sometimes, we’re brave enough,” says Cumbria County Council corporate director for economy and highways Dominic Donnini. “I’m not a fan of building big walls around houses. There’s no guarantee the water won’t come over the top of them. We need new solutions.”

Many agree that there are plenty of examples of new solution – particularly from abroad, in such places as the Netherlands – floating houses to name just one. And while this is being adopted elsewhere, in the UK adapting housing stock design is still some way off.

Historically when the UK has built on flood plains it has been a “bit of a mess”, suggests Mott MacDonald global water practice leader for rivers and flooding Fiona Barbour.

Fiona barbour crop

Fiona barbour crop

Barbour: Flood plain development hesitancy

“The result is we’re now hesitant to build on flood plains, even brownfield sites,” she concludes. “But it is possible that building on flood plains can be a catalyst for development and opportunity.”

Discussions in the industry around potential opportunities for development points to the suggestion by insurer and investor Legal & General (L&G) that there are questions about engineers’ competence to make real these opportunities. L&G  is demanding evidence from the engineering professional bodies about measures they have in place to ensure that the professionals offering advice are up to speed on climate risk (see p32).

I’m not a fan of building big walls around houses. There’s no guarantee the water won’t come over the top of them

Are engineers failing to give sufficient professional assurance to those who hold the purse strings that climate resilient developments are a worthwhile endeavour?

“Technically it’s possible to build [climate resilient] houses, but you’re not going to get volume housebuilders building them, because it doesn’t make financial and commercial sense,” says Countryside Properties engineering manager Tim Haines. “Essentially, housebuilders will build houses in the places that are the easiest. The initial flood defence investment needs to be in place.”

Haines is sceptical about at the idea that housebuilders could, perhaps help to initiate that early investment. “Who would we approach? The mechanism just isn’t there.”

Essentially, housebuilders will build houses in the places that are the easiest

The bottom line is that there is little evidence that the major housebuilders’ motivations will shift from the more familiar focus on building more, and building more cheaply. Especially when they can see that government policy looks set to support their interests and that building on flood plains often means mitigating for poor ground conditions with costly engineered solutions such as piling.

It will be interesting to see the ICE’s, and other institutions’, responses to the L&G request and whether the clarity of the engineer’s role in sustainable development comes through.

Someone should take the lead, as many in the housebuilding and flood defence worlds agree that funding streams are “unbelievably complicated”, suggests Donnini.

Dominic donnini crop

Dominic donnini crop

Donnini: Need for understanding of liabilty

Design accountability

For now, there is often “no understanding of where design accountability and liability sits”, continues Donnini. He argues that developers failing to take responsibility for flood protection infrastructure poses a significant problem.

Added to which, they often use umbrella companies and create new entities for individual developments to enable them to stay at arm’s length from future comeback if resilience issues emerge.

“When there’s a new [arm’s length] company, there’s no reputational damage [to the parent firm],” he asserts.

Concerns about data

There are also concerns about the usefulness and  robustness of data and analytics tools that determine the flood risk for any UK development.

“We are making great headway in flood risk analysis,” maintains Environment Agency national lead for development and flood risk Andrew Eden, before accepting that this headway is “not well understood” by developers.

Haines remains sceptical: “Can we even trust the flood risk analysis? We always treat it with caution.”

Can we even trust the flood risk analysis? We always treat it with caution

This is a blistering critique of the fundamentals on which many engineers base their own work.

But there is reason to begin questioning these principles, as they may hold the key to why the UK continues to build houses in a similar manner over consecutive decades with limited innovation.

Modifying standard designs

Volume housebuilders tend to have standard home designs. These could be easily modified to be more resilient. But this comes down, again, to finding someone in development industry who will take the risk.

This argument partly centres on the the stigma of building or living on a flood plain.

It is a stigma that is just that, and not reflective of reality, argues National Flood Forum chief executive Paul Cobbing.  He points out that in recent years, many insurance claims for flood damage actually come from properties in areas that have not been identified as being flood risk zones.

Tim haines cropped

Tim haines cropped

Haines: Treating flood risk analysis with caution

It is a fact that while more than 2.44M properties at risk of flooding from rivers and the sea, another 3M more are at risk from surface water flooding. Countless more are at risk from sewer flooding.

“All houses are at flood risk of some sort – and that is a conceptual issue,” says Cobbing, before asserting: “It’s the thinking and planning for an adaptive process that’s needed.”

After the floods of 2007, which claimed 13 lives and devastated parts of the country, Sir Michael Pitt was asked to carry out a review of the country’s flood defences.


Pitt Review: Key recommendations

His full report contained 92 proposals he said must be implemented if communities are to be better protected.

The key recommendations were:

  • Publish a 25-year plan to address the issue of flooding, along with the creation of a dedicated Cabinet committee
  • Overhaul building regulations for homes built or refurbished in flood-prone areas - these should stipulate appropriate construction materials and techniques and detail what drainage systems should be put in place
  • Building on flood plains should be the “absolute exception”, done only in areas of genuine housing shortage where no alternative land is available
  • Produce definitive electronic maps of all drainage ditches and streams, making clear who is responsible for maintaining them - these should be drawn up by local authorities, which must take a stronger overall lead on flooding l Introduce greater openness in the property market to ensure that buyers have a clear understanding of the risks of buying in a flood-prone area - local authority searches and Home Information Packs should both be required by law to carry that information

Debate participants

This report is based on a dinner debate that took place in London in November. The participants were:

Fiona Barbour, global water practice leader for rivers and flooding, Mott MacDonald

Paul Cobbing, chief executive, National Flood Forum

Stephen Cox, economist, Mott MacDonald

Matt Crossman, flood risk management lead, National Infrastructure Commission

Granville Davies, manager of asset strategy, Yorkshire Water

Dominic Donnini, corporate director for economy and highways, Cumbria County Council

Hazel Durant, head of water and floods integration, Department for Environment, Food and Rural Affairs

Andrew Eden, national lead for development and flood risk, Environment Agency

Peter Geraghty, director of planning and transport, Southend-on-Sea Borough Council

Neil Gibson, managing director for transport, economy & environment, Buckinghamshire County Council

Tim Haines, engineering manager, Countryside Properties

Mark Hansford, editor, New Civil Engineer

Paul Mackie, strategic funding manager, Coastal Partnership East

James Morris, head of flood and coastal erosion risk management, Welsh Government

Clare Wildfire, global practice leader for cities, Mott MacDonald

Alexandra Wynne, deputy editor, New Civil Engineer

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