Alpha House that Jacks Built

Our Deputy Chair, Paul Maddocks, has been researching one of Coventry’s “firsts”!

M2-33_0Over the past few months I have been looking at some of Coventry’s ‘Firsts’ from the city with the first traffic free shopping precinct to the city centre with the first smokeless zone. Coventry has always been the hotbed for trying out new technology and ideas. Right back to 1868 when Rowley Turner, a sales agent of the Coventry Sewing Machine Company brought a French velocipede cycle from the Paris Exhibition to Coventry to start making copies of them and then the city improving on the design to opening up the cycle industry and the development of the cycle we have today. It was Coventry that the German Daimler company chose to set up the first British manufacturing of motor cars because of its skilled and technically minded work force.

So again when the inventor Jansz Joost Werner, from Hague in the Netherlands, came up with a new novel way of building fast and cheap tower blocks of flats he came to Coventry. Working with Richard Costain of Costain Construction Ltd., his idea was to build the roof and top floor first at ground level on a large number of jacks. It is then jacked up and another floor is built underneath it. What is now a two story block is jacked up another level and the third floor and walls built underneath.

The jacking devices acts directly on the central core structure which, together with the projecting floors, provides a substantially rigid structure. The jacks raised the building at a rate of half a metre an hour!  When all the floors are completed it is then anchored to the foundations, it was known as the ‘Jack Block’ system.

So why build it in Coventry? The city was a ‘boom town’ in the 1950’s and 60’s with full employment. Loads of people came to Coventry to work, so housing was in very short supply. The Coventry County Borough Council were on the largest building programme in history and one and two bedroom flats were very much needed. So if they could be built quickly and cheaply the council would try it.

The world’s first building to be built using the ‘Jack Block’ system was Alpha House in Barras Heath  in 1963.

Crystal Palace Exhibition

It came as a light bulb moment when I realised why this 17-storey residential tower block of 97 flats was named ‘Alpha House’.  Alpha is the first letter of the Greek alphabet and is used to designate the first of its kind and Alpha House is the first of its kind!

What are the advantages of building the ‘Jack Block’ way? Besides being quick and cheap, the building would be built on site in a factory type of way giving the advantages of being able to work in all types of weather as it was the roof that was built first. Heating and lighting could be easily available and all trades working on the ground level meant they did not have to have loads of scaffolding, heavy cranes and hoists to get worker and materials up and down the building. As each floor would be completely built it would then be jacked up and the process would be repeated over and over again. Each floor could be completed in about a week so 16 floors would only take 4 months then after final fitting the building could be ready in around 5-6 months.

What are the disadvantages? the building process relied on all materials and trades people arriving on site and doing their work in a systematic sequence and on time before the floor was jacked up. If there was any delay or work not completed it could become very expensive, especially if the fault was high up on the outside of the building.

There have been approximately 10 buildings in the world which have been built using the system since 1963. Mercia House, in the Lower Precinct, was the second one in Coventry.

So when I was looking for architectural firsts I was pleasantly surprised to find that in 1963 the very first block of flats to be made where the roof and the top floor are made first was Alpha House, the ‘Jack Block’ system way.

In 2010, nearly fifty years after it was built, Alpha House was renovated by the Whitefriars Housing Group at a cost of £1.97 million. The building was over-clad with aluminium panels and windows were replaced. “The externally refurbish Alpha House went extremely well and we are delighted with the outcome which provides high quality accommodation for our tenants.” stated the Whitefriars Housing Group now called Citizen Housing.

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I will be looking for some more ‘Coventry firsts’ so if you have any you know about please let me know and I will look them up.

Paul Maddocks

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