Reasons for participating in the competition(s)

An amphibious house is a building that rests on the ground but whenever a flood occurs, the entire building rises up in its dock, where it floats, buoyed by the floodwater. Amphibious construction brings together standard components from the construction and marine industries to create an intelligent solution to flooding. 

The house itself sits in the ground and the floating base is almost invisible from the outside. Amphibious designs can vary to suit the location and owners’ preferences. 

The amphibious design allowed the floor level to be set less than 1m above the ground level instead of 2m, had the house been static. This enabled a 225sqm 3-bed dwelling to be constructed over three floors in place of the existing 1-storey 90sqm house without significantly increasing the ridge height, and therefore achieved full planning. 

Construction is slightly more expensive than mainstream house building due to the requirement for two foundation systems: the dock and the hull; but overall the costs are comparable to a typical basement extension, or around a 20-25% uplift on a similar size new house. The technology is ideally suited to areas of high flood-risk or if there is uncertainty regarding future flooding levels, as well as in historical or sensitive landscape settings where more heavy-handed solutions would be unacceptable. 

How it works

River and ground water are hydrologically linked, so during a flood here as the River Thames rises so too will the ground water beneath the surface. The dock fills gradually from the ground, gently raising the building, as the river level rises. When the water is just below the ground level the house becomes buoyant. The house can rise up to 2.7 m to cope with a 1 in 100 flood event. The guide posts extend almost 4 m above the ground level such that in the event of an even bigger flood the house would still be retained between the posts. The flexible pipes are designed to extend up to 3m allowing all of the services to remain clean and operational during any flood event and crucially to allow the occupants to return to the property immediately after a flood, maximising the continuity of their daily lives. 

Maintenance 

The Amphibious House is designed with minimal moving parts but like any house it requires maintenance and like a car or a boat it requires testing. The house may not float for several years therefore it is important to proactively test and maintain the can-float base and flotation system to ensure that the parts are in good working order, ready for when a flood occurs. 

Every five years the dock will be pumped full of water to repeat the flotation test when the house will rise up to 50 cm to test the integrity and free movement, before the water is slowly released and the building allowed to touch down again. 

Landscape/Hydroscapes

A carefully laid out garden acts as a natural flood warning system. Terraces set at different levels are designed to flood incrementally and alert the occupants well before the water reaches a threatening level, as an ‘intuitive landscape’ The lowest terrace is planted with reeds, another with shrubs and plants. The lawn is located a level above and the terrace is located at the highest point, immediately below the living room. The terraced levels improve recovery by providing dry areas as water levels drop, and the plants help to reduce siltation of the dock.

The limited plant diversity and hardstanding on the previous site was replaced with a variety of plant species and more absorbent surfaces.

The Environment Agency required that native plants such as Cornus sanguinea be used along the sensitive riparian zone adjacent to the river. The concrete river edge was replaced with timber piling, over which planting could grow, to create a softer, more natural river edge with shelter for fish and spawn.

Background

Architecture plays a critical role in mitigating flood risk and improving communities’ health and wellbeing during flood events. Flooding is one of the greatest environmental threats in the UK, causing an average £1.4 billion in damage a year to businesses and households. The impact of flooding is far greater than the resulting financial costs, disrupting thousands of lives and livelihood in and inflicting profound health and wellbeing impacts. These can be long-lasting and extend far beyond communities that were originally flooded.

Cities which today start to embrace water and take advantage of its benefits, whilst understanding the threat of climate change and flooding, will be cities that perform better economically, socially and politically in the next 20 to 30 years and beyond. Through this balanced approach we can create cities that are better prepared, adaptable and are fit for the challenges of the 21st Century. The Amphibious house is an important case study in addressing these challenges.

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