Location:
Watford, UK
Status:
Completed
Scale:
3-bedroom house, 225sqm
Constraints:
Flood zone 3, conservation area,
no UK planning precedent
FLOOD RESILIENT HOUSE
BRE Flood Resilient House
The UK’s first Amphibious House.
A small island located on the River Thames, in south Buckinghamshire, is home to 15 houses. The houses, which were mostly built before the 1950s, are typically raised about 1 m off the ground on timber piles to protect them from flooding. At the time of construction they were only built high enough to protect them from regular flooding rather than extreme flooding. When the owners of one house on the island plan to be built their home they discovered that the floor level would need to be raised a further 1.4 m above the ground level to cope with the predicted extreme. This would’ve resulted in a house with its ground floor elevated 2.5 m above the ground. The house was also subject to Conservation and Environment Agency rules.
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A small island located on the River Thames, in south Buckinghamshire, is home to 15 houses. The houses, which were mostly built before the 1950s, are typically raised about 1 m off the ground on timber piles to protect them from flooding. At the time of construction they were only built high enough to protect them from regular flooding rather than extreme flooding. When the owners of one house on the island plan to be built their home they discovered that the floor level would need to be raised a further 1.4 m above the ground level to cope with the predicted extreme. This would’ve resulted in a house with its ground floor elevated 2.5 m above the ground. The house was also subject to Conservation and Environment Agency rules.
The solution was an amphibious house, a building that rests on the ground when conditions are dry, but rises up in its dock and floats during a flood. The house itself sits in the ground and the floating base is almost invisible from the outside. The ground floor of the house is raised above the ground by less than 1 m rather than by almost 2 m as will be required if it were not amphibious. This approach meant that the 225m² three-bedroom dwelling could be constructed over three floors in the place of a single-storey 90m2 house without significantly increasing the ridge height.
The site is located in the middle catchment of the river Thames. The river is wide and navigable and requires a large rainfall before it floods. Flow gauges installed along the river help to provide two more days early warning of a flood. However, when the site does flood it can last for several days.
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 flood water reaches a threatening level – at Baca Architects, we term this 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 plants help to reduce saltation of the dock.
The amphibious house is connected to its utilities via elephant cabling. These flexible service pipes are designed to extend up to 3m, allowing all of the services to remain clean and operational during any flood event. Crucially, this also allows the occupants to return to the property immediately after a flood, maximising the continuity of their daily lives.
A float test was conducted during construction when the wet dock was filled with the water and the house elevated half a metre under its own buoyancy. The house was also tested again once the steel frame was complete and the house filled with furniture.
Between November 2019 and February 2019, severe winter flooding occurred across the United Kingdom. During this period the River Thames swelled and the owners of the #AmphibiousHouse, as featured on Channel 4’s Grand Design series reported: “the house continues to rise and fall without intervention”.
This project has led to much excitement in the industry as it is the first of it’s kind in the UK and has set a precedent for alternative approaches to building in a future of increased rainfall and flood.
The Amphibious House has won multiple awards for innovation.
‘It would be wonderful if we could collect material of the Amphibious House for the V&A collection. It works well with the V&A’s desire to collect designs that relate to the improvement of society.’
-Dr Olivia Horsfall Turner Curator, Designs Victorian and Albert Museum + RIBA Architecture Partnership Lead Curator
Laying foundations for insurable, flood resilient properties.
The Resilient Repair Home acts as a fully working testing station, testing the design and installation of retro-fit flood resilient measures and how they perform in operation. The Grade II Listed Property is located at BRE Innovation Park at Watford, UK. The testing facility builds on the BRE/Baca co-authored publication: Flood Resilient Property for Defra and more recently Ciria’s publication: Code of Practice and Guidance for Property Flood Resilience.
The BRE Flood Resilient Repair Home aims to show alternative replacement products in the repairs that will not be affected by subsequent flooding; products that are resilient. It also shows how simple measures such as placing electrical outlets higher up walls and using doors and windows with flood resisting seals can help minimise future damage. And, if water does get in, an automatic 'sump pump' connected to drains in the floor quickly gets water out of the house again.
Code of practice for property flood resilience (C790F)
This work paves the way for pro-active and retrofit Flood Resilient Repair measures. Baca Director, Richard Coutts FRIBA, on behalf of the RIBA Policy team is lobbying the UK Government to adopt flood resilience measure within the UK’s Building Regulations. It is proposed that the type of measures required would be linked flood zoning and accounts for Climate Change. Therefore, new dwellings in Flood zone 1 would require less measures than those located in flood zone 2. And replacement dwellings located in flood zone 3 would be provided with constructional guidance for amphibious, wetproof or elevated buildings.
BRE Flood Resilient Repair Home > Typology: Wetproof
Baca Architects have recently created a demonstration home as part of the BRE Innovation Park at Watford which has been adapted to be resistant to flooding from water up to 600mm (2 feet) deep, and to be resilient to the effects of being flooded beyond that – in other words, it is designed to dry out quickly and be suitable to move back into in a very short time after a flood incident.
At present, following a flood, builders repairing a flood damaged home would strip off soggy plasterboard, take out the flooring and rip out a saturated chipboard kitchen. But, once the house has dried out, then they would very likely put plasterboard back in, install a new chipboard kitchen, and use non water resistant flooring and insulation materials, which, if the home were to flood again in the future, will suffer the same fate.
The Flood Resilient Repair Home aims to show alternative replacement products in the repairs that will not be affected by subsequent flooding; products that are resilient. It also shows how simple measures such as placing electrical outlets higher up walls and using doors and windows with flood resisting seals can help minimise future damage. And, if water does get in, an automatic 'sump pump' connected to drains in the floor quickly gets water out of the house again.
Although the house is designed to be water resisting and resilient, it still looks and feels 'homely'.
Resistant and resilient measures used in the house include:
- Water resistant insulation in the walls and under the floor (such as spray applied PUR foam or injected foamed cavity insulation)
- Kitchen units and doors made from resin bonded board, and fitted with all ceramic worktops Waterproof magnesium oxide wall boards instead of plasterboard, or, if plasterboard is used, this fitted horizontally so that in future only the lower boards need replacement if damaged
- Ceramic tiled floor and loose rugs in place of fitted carpets.
- As well as these measures, other things have been done to keep vulnerable items out of the way of any future flood water:
- Sockets and switches placed higher up the wall, and the wiring to them all coming from the ceiling Appliances in the kitchen (fridge, oven, washing machine etc) mounted at worktop height
- The lower kitchen cupboards fitted with slideout baskets so that they can be taken out and placed on the worktop if flooding is imminent
- To prevent flooding entering the property by seepage from under the floor (which happens as groundwater rises, even if floodwater doesn’t reach the door)
- Membranes installed under the floor and in the walls* to divert water towards…
- Drain channels beneath the floor around the perimeter of the room, directing water into…
- A sump in the corner of the home fitted with automatic pumps to remove the water, pumping it outside, before it can reach up to the floor.
- (*the membrane in the wall means that if the adjoining property floods, water that seeps through the wall from next door is channeled away to prevent damage on your side. This allows repairs to start even if the neighbouring property is still affected.)
- And finally, to stem the flow of any flooding that reaches above the door sill level: Enhanced seals and locks to the doors and windows to make them floodproof Air brick covers
- Oneway valves in the main drains to prevent water coming up into the home via the sewers.
As seen on BBC Countryfile
For the filming for BBC Countryfile, several thousand litres of water was poured into the home. Although this only created a shallow 'flood', this would have caused severe damage to most homes, and taken days or weeks to properly dry out. Here, just an hour after filming was completed, the water had all been removed via the floor drains and sump pump, the floor was dry and you would not have known that the house had been flooded at all.
The Environment Agency’s Emma Boyd visited the project. Emma Howard Boyd is the Chair of the Environment Agency, an Ex officio board member of the Department for Environment, Food & Rural Affairs, and has recently been appointed as the UK Commissioner to the Global Commission on Adaptation.
SITE COMING SOON
