top of page

BLOG

Canvey Island and it's Unique Building Techniques and Issues



Canvey Island is a unique location for many reasons and is a place I will always call home. From it's relationship with the River Thames (being below sea level) to an area that is predominantly made from alluvium, Canvey Island has a number of challenges that make building extensions and new houses here an individual challenge. 

 

History

 

Habitation of Canvey Island is believed to have started as far back as 2000 years ago when during the Iron Age it was used as an offshore pasture. However, living upon Canvey Island became more prominent when Dutch immigrants set up home here in the 17th Century. Dutch influence runs strong throughout the area with the original Dutch Cottages which still stand today and many of the road names being of Dutch origin. 

 

Fast forwarding a couple hundred years and Canvey Island became a visitors haven with Frederick Hester planning to turn the area into a holiday destination. However, a number of factors caused that vision to change with Canvey becoming a popular place for many people to call home with Southend becoming the main visitor attraction for the South East of Essex.

 

From the start of the 20th Century, Canvey Island was often split into 60' x 60' plots with timber roughcast bungalows being popular and built across the island for homes and holiday properties. In some areas, there were larger plots where residents would also have livestock upon the land. Many of the residents at the time were moving away from London and heading to the Canvey to retire or for a different lifestyle whilst being able remain close to the city. 

 

I could go on more about the history of Canvey, but there are some fantastic websites such as www.canveyisland.org/ and www.beyondthepoint.co.uk/ which already delve in to this so follow the links to check these out.

 

Soil Conditions and the "Canvey" Raft Foundation

 

Canvey Island is predominantly made from alluvium, soil collected from the River Thames and deposited along the coast and then reclaimed for housing. You'll find the majority of Canvey Island beneath top soil is London Blue Clay. This soil type has it's uses, however how Canvey Island has been formed unfortunately means that the bearing pressure available is limited. 

 

This means that most of the buildings here have had to utilise a type of foundation which you may not find in all places, a Raft Foundation. This is a type of foundation that runs underneath the entirety of the property, however to a relatively low depth, typically around 300mm deep. Other types of foundations I've seen in older buildings include a "Ring Beam" style foundation, brickwork foundations and even some smaller timber buildings built off concrete blocks. 

 

In newer properties, you'll find the raft foundation easily. Most properties, you'll find a concrete path that runs around the property around 800mm - 1000mm beyond the external wall of the building. This is in fact, the foundation to the house that not only provides a handy path, but helps protect the property from frost and heave issues. Foundations are typically reinforced with steel mesh to ensure they remain strong for years to come. 

 

Drainage Issues

 

One of the major issues for the island is drainage. Canvey was historically made up from a network of drainage ditches which ran throughout the area. Whilst most of these are now changed to pipes underground, there are some main ditches still present that feed into the lake and other drainage areas such as around Cornelius Vermuyden and Thorney Bay. 

 

These ditches often became property boundaries which you can still see to this day. If you look closely on Aerial Maps, you can see fences which are curved or run at an angle through multiple roads such as the examples you can see below. Drains are often still present as large pipes up to 1m in diameter and building near or over these is strictly prohibited. 



During heavy rainfall, Canvey Island can also suffer from flooding with two major events occurring in 2014 and 2016. I remember distinctly the 2014 event as I happened to be visiting Movie Starr to watch "Dawn of the Planet of the Apes" that got abruptly cut short due to the rising flood water at the cinema entrance. 


A number of factors such as our soil type, pumps breaking down and unmaintained pipework contributed to these events. Governing bodies have improved the maintenance of the drainage system to help prevent these events happening again however there's little that can be done about the soil. 

 

The type of soil present here, mixed with our high water table as we are below sea level, prevents water being able to drain into the ground. This is why you'll often find your garden or grass areas such as Waterside or Smallgains being waterlogged during heavier than typical rainfall. 

 

New housing and commercial developments seek to improve the drainage by including attenuation systems that improve drainage within the area. The aim of these developments is to work to SUDs principals by attenuating and then cleaning rainwater before discharging into the mains system. Whilst no-one wants to see us lose green spaces, you'll often find that the drainage is improved in the area by the construction.

 

Tidal Flood Impact

 

Being below sea level, Canvey Island is at severe risk from flooding by the River Thames. However, we benefit from some of the best sea defences in the country with a 14km concrete sea wall that runs around the perimeter of the island. The Environment Agency has classified the area as Flood Zone 3a, and development in these areas are strictly monitored.

 

Ideally, the National Planning Policy Framework seeks to locate development outside of these areas. However, development is allowed if it meets the Sequential and Exception tests as set out by the government. Canvey Island is a distinct location and meets these tests as it has an identified need for Social, Economic and Physical Regeneration that simply cannot be met elsewhere. You could say, Canvey is a victim of it's own success, with a population of circa 40,000 that now needs to be sustained and is growing. As such, development of new housing is often acceptable as long as it can prove that the occupants are safe during the event of a flood.

 

Evacuation of Canvey during a flood event would be extremely difficult due to the limited road network. Therefore, in order to do this, the best way to protect occupants is to provide a "Safe Refuge" above the flood depth. New properties are designed to be protected from collapse in the event of a flood with occupants being able to remain safe upon the first floor. All new houses will also have a Flood Response Plan to aid occupiers in what to do. We often provide these for new developments in the area.


This is again why, you'll notice that there are very few, if any, new build bungalows being constructed upon Canvey.


I have worked with Structural Engineers to model and develop wall constructions that protect properties from pressures that would be exerted upon buildings during a flood event. These are known as Hydrodynamic and Hydrostatic flood pressures and is a crucial part of new buildings.



New Buildings and Homes on Canvey 

 

As mentioned, Canvey Island is a victim of it's own success. Whilst a number of you reading this would ideally not want to see any new houses in the area built due to the issues, there is a population that needs to be protected. We all want to see the younger generation thrive, however without new, affordable housing they will struggle to sustain a life within the area. 

 

I believe, development should be supported where it can be sustained, and major planned developments such as that by Canvey Road, Roscommon Way and even Jotmans in Benfleet will go ahead in the near future, whether we think they should or not, to meet growing demand and shortages of housing. 

 

These developments should be used to offset the cost of providing a Third Road to Canvey Island which is unlikely to be considered due to the significant investment that would be needed. Residents of the Island have been calling for a much needed third road for 30 years yet there has always been little support from local or national government considering the costs that would be required. These developments could help provide affordable housing for local people but can also be a platform to improve access and facilities for the island.

 

New housing shouldn't be met with an automatic "No", but should be used to seek ways to improve and create affordable housing for the area whilst ensuring developments are designed to meet Canvey Islands unique issues. These developments should be used to improve the area for all and provide a safe, affordable place to live for the local population.


"Good buildings come from good people, and all problems are solved by good design" - Stephen Gardiner OBE, Architect


96 views0 comments

Recent Posts

See All

Comments


bottom of page