Guest essay by Eric Worrall
There have been a few stories in the press lately about climate proof floating houses. As someone who used to live next to a river, I’m concerned floating house advocates have no idea what they are talking about.
Climate change may lead to a rise in floating architecture
Published 5th January 2018
Trudie Carter, Dezeen
Climate change poses a serious question: how will our cities cope with rising sea levels? Some architects believe that floating buildings offer the answer, and have come up with a wide variety of designs to prove it, from simple prefab homes to entirely amphibious neighborhoods.
Leading the charge is the Netherlands, which has long been a pioneer of water-based living. With over half of its landmass underwater, the country has a well-established canal infrastructure, but is also now taking even more ambitious leaps to transform its cities.
In Amsterdam, a new breed of contemporary houseboats has been popping up all over the city. Among these is a slatted timber structure by Framework Architecten and Studio Prototype, which shows how floating homes can easily feature a story submerged below the water.
A more ambitious proposal is also planned for the Dutch capital — earlier this year, Danish firm BIG and Rotterdam studio Barcode Architects revealed designs for a huge housing complex that will float on the IJ lake. The 46,000-square-meter building will provide a gateway to IJburg, a whole neighborhood set on artificial islands.
My biggest concern is the expense. Water is a very corrosive environment, far more so than most people probably realise. Concrete floats usually only last 20 years or so, because they are continuously getting knocked about by the water and objects in the water, and corroded by minerals in the water. Anything sitting on top of those floats is also subject to enhanced corrosion – floating structures tend to deteriorate much quicker than land based structures. Floating structures require expert inspection on a regular basis.
Not a solution for poor people – only rich people can afford to keep their floating houses well maintained and safe. Poor people can live in floating structures, can ignore the recommended inspections which they can’t afford, but the safety risks are substantial.
Attaching emergency floats to a house which normally sit on land is a recipe for disaster, unless the owners of those houses are knowledgeable about the issues and take charge of their personal safety. The floats will work, the rest of the house might break during a flood, as the floats exert new stresses on the house frame.
When a hurricane or storm hits, there is no guarantee your floating structure will survive any better than a fixed structure. Look at the aftermath of any hurricane (e.g. picture above), all the heavily damaged boats which have broken their moorings. Boats are tough – but there has to be a little give in the mooring to support easy vertical movement of the structure as it floats. The coupling has to be slightly loose, to minimise the risk the vertical movement will jam. This loose coupling leads to problems in harsh weather. High winds, especially hurricane force winds, and rough water cause the floating structure to repeatedly slam hard against its mooring. For big structures, each impact will exert 10s, even hundreds of tons of impact force on the mooring and the floating structure. This slamming action in extreme conditions frequently leads to mooring failure, expensive structural damage and / or complete destruction of the floating structure.
If flood floatation events are expected to be rare, the is a substantial risk of substandard construction work on mooring fixtures which likely won’t be tested for a decade or two after the house is built. A little extra sand added to the concrete to cut corners and save some money wouldn’t be noticed until the concrete mooring foundation is stressed by the flood, by which time it would be impossible to work out who was responsible for the failure.
If someone wants to live in a flood prone hurricane risk area, there is a much simpler, cheaper solution to flood risk than a floating structure; don’t buy a house on low lying ground on a floodplain.