Kabina’s unique method for sustainable development in flood meadows enables great new homes to be built adjacent to existing infrastructure, in places where people want and need to live.
Types of flooding
We are all aware of global warming, climate change and increases in rainfall and flooding.
Winter precipitation trends across the UK for the 2080s. The increase ranges from +14% in the northeast to +23% in the southwest. The Thames Valley increase is within this range.
A report by IPCC in 2013 indicated that mean sea level would rise between 0.52m and 0.98m by 2100 due to melting ice sheets.
Sources of flooding:
- Rivers – when water overtops the riverbank
- Coastal (and tidal) – when seawater is driven on to land by storms and high tides
- Surface water – when excessive rain cannot be absorbed into the ground and runs off hard surfaces too quickly to be discharged
- Sewers – when too much rainwater enters sewers
- Groundwater – when below-ground water rises above ground level
- Artificial structures – failures such as burst water main or collapsed embankment
Terrain can be divided into upper, middle and lower catchment areas.
River basins, such as the Thames Valley, are in middle catchment areas.
The rainwater catchment area is larger than in the upper catchment, rainwater takes longer to reach the river and so large areas of rainwater can remain on the land for several days following a flood event.
Defra recommends that in such an area the rivers and floodwater should be allowed to flow.
Other recommendations are that roads are elevated above flood level and that planted open channels are created to provide drainage routes.
Flood types in a middle catchment such as the Thames Valley: mainly river flooding but also surface water, sewers and groundwater flooding.
Upper areas are in higher altitude locations such as the Peak District and Snowdonia; lower areas are typically coastal locations.
There are two ways to cater to flood events: raised foundations or a can-float system.
The default historically in the UK, US and elsewhere has been to raise the home so that the ground floor level is hopefully going to be higher than the level of flooding, often leaving a sacrificial lower level (void, basement or garage) which can take flooding at a cost that is deemed to be acceptable.
In the UK, where flood heights are generally less than the southern states of the USA the default is for ramps and raised homes. The homes have some flood mitigation measures such as ramps, washboards, raised electric points and perhaps sacrificial basements. They suffer from waste ingress in a serious flood but the damage is limited or mitigated by such measures.
The government refers to this as ‘flood resilience’, ie the homes are resilient and might suffer damage at an acceptable level.
Building on stilts or piers is commonplace across the USA. In low density coastal regions stilt foundations are almost transparent to tidal flows. However, when used as a defence against storm flooding this method can be vulnerable to heavy items of debris borne along on fast moving floodwaters. Furthermore houses that are permanently raised off the ground are not particularly convivial, nor is there any guarantee that a severe flood will not reach them. The recent flooding in Texas has proved the point. Public and governmental resistance to development in flood zones is most prevalent in high density housing environments, where councils naturally seek to prevent to new building schemes that may exacerbate or increase the existing threat of flooding to their homes.
This is relatively new to the UK and is more established in Holland. Flooding in the UK has not been on such a scale historically to justify the investment and rollout of can-float systems. However, with the impact of climate change and the increasing need for new homes, particularly given the desire to avoid greenbelts, the idea of can-float homes in flood zones is gaining acceptance as it is recognised as a means of providing full ‘flood resistance’ as opposed to mere ‘flood resilience’.
The Kabina Home responds to extreme flood conditions by adapting to varying water levels and flow rates. The Kabina house foundation system and landscaping give homeowners a great lifestyle, promote flora and fauna and can take surrounding neighbourhoods out of flood risk by providing effective flood management. The house design celebrates the deck which runs around the whole house and extends 3m at the back of the house to create outdoor recreational and dining space. The design is inspired by Japanese architecture, notably the flat-angled pitch roof and overhanging eaves and the adoption throughout of the 2:1 proportion. Kabina has sought to create harmony, balance and proportion, to eschew pastiche and to arrive at a semblance of both tradition and innovation. The Kabina home sits on a buoyant concrete box foundation and has robust guiding piles to ensure that it rises and falls safely and securely if there is an extreme flood event.