How can better design help us build more safely in flood zones?

Posted by Derek Mason

21st January 2020

We have seen a number of floods in recent years, with the media describing them as “unprecedented”. The implication is that these floods were unavoidable and homeowners have been unlucky.

However, building practices in England mean that homes are often built in high-risk areas. According to The Environment Agency, a high-risk area is one that has a greater than 3.3% chance of flooding each year.

And over the last few decades – between 1989 and 2016 – more than 300,000 homes have been built in high-risk areas. Essentially, these homes have been built on floodplains and in coastal areas where flooding is a distinct possibility.

Therefore it is the planning system itself that has been a factor in increasing the risk of homes being flooded.

The floods in Fishlake, near Doncaster, in November 2019 showed exactly what can happen when we build on floodplains. Fishlake lies beneath the high water level of the River Don, and back in the days when it was farmland rather than houses, farmers avoided planting crops there because the ground was so waterlogged.

It is not surprising that 500 homes were flooded when the river broke its banks. Even the name of the area, Fishlake, should have been a clue as to the likely outcome of building there.

Clearly, the ideal scenario is that developers stop building on flood plains. However, that seems unlikely to happen. A Greenpeace investigation has found that 9,688 new homes could be built on some of the most flood-prone areas of England… including hundreds of new build homes in Sheffield and Doncaster.

Proposed developments include 3,100 properties in a “new town” less than two miles from Fishlake, and more than 5,000 homes in a high-risk flood zone in Lincolnshire.

If developments are going to continue, despite the risks, it would make sense for developers to build homes that are “flood proof”.

It is not always straightforward to make a home flood proof, and it is not always budget friendly to do so. But it is something that needs to be addressed.

A recent project on Eel Pie Island in Twickenham – where the Rolling Stones performed before they hit the big time – saw us designing a timber-framed house on stilts. And we have done a few of these along the Thames where homes have been raised up well above the water level.

Another innovative solution seen along the Thames near Marlow, in Buckinghamshire, is an amphibious house that is designed to rise upwards when the area floods. Since the house moves with the water, there is no need for stilts.

If developers can embrace flood-resistant designs, then continuing to build on flood plains won’t be a problem. The fear is that standard homes will continue to be built in high-risk areas, causing inevitable problems for the people who buy them.

If you need assistance with the structural elements of an upcoming project, whether or not it is in a flood zone, please do get in touch.

Looking for help with your project?

It is our technical prowess for modern, clean design and astute commercial acumen that results in saving clients’ time and money.

Tell us about your project
RBA RBA The Instituition of Structural Enginners Trada member ACE
ISO-9001-UKAS ISO-14001-UKAS ISO-45001-UKAS