Fascinating facts about the Barbican estate’s construction

  1. In the building industry it is traditional to have a ‘topping out’ ceremony when a building is completed. On a particular occasion on the John Laing site, to honour tradition they put the City of London flag and the Union Jack on the top of the building ready for the ceremony the next day. There was a large number of Irish builders working on the site. Overnight some of them switched the Union Jack to the Irish flag – green, white and gold. It wasn’t noticed until the ceremony was already well under way. Apparently, one of the Royal family was there. There was a panicked scramble by the managers to swap the flags.
  2. All the walls and floors of the buildings were made on site.  Carpenters had to create boxes – called ‘shuttering’ – as frames to contain the wet concrete for the size of the required wall or floor. The shuttering was made using three-quarter inch plywood. Then the concrete was poured in and left to set.
  3. The walls would also have metal backs bolted to them. Then they would be hauled up by a crane, leaving the shuttering behind. When the walls or floors were dropped in place they would be bolted together.
  4. The concrete walls were thicker at the bottom because they had to carry more weight. The slabs might be 2 feet or 18 inches think. Higher up the building, with less weight to carry, the walls might be reduced to 12 inches thick.
  5. As many as a thousand workers were employed on the site at the height of the construction process.
  6. When work on the Turriff site started, the toilet for the workers was a hole in the ground with quick lime. The company refused demands for flush toilets. They said they would only install some then the buildings were two storeys high. (This is what passed for incentive arrangements in the 1970s.) So the workforce started walking to St Paul’s Cathedral to use the public toilets there. Very quickly proper flush toilets were provided on site.
  7. Two main contractors tried to quit the site before their part of the development had even been completed. One succeeded (Turriff).
  8. Industrial relations were so bad that the project was bedevilled with strikes – official, unofficial, and wildcat – culminating in work being suspended for a year on the Myton site. There had to be a Government sponsored court of enquiry to settle the dispute.
  9. On the Myton site, a crane was put up but someone forgot to put in the blocks to hold it in place, and when it picked up a large shutter the crane fell over. No one was seriously injured fortunately.
  10. In May 1976 there was an all-out strike for two weeks at the Barbican Centre site because of Laing’s refusal to remove asbestos safely from the site. They had workers simply sweeping the dust up.
  11. On Laing’s site, a worker was decapitated by a hoist. He stuck his head through a hole in the lift structure to see if the hoist was coming up. It was, but he had not realised that the counterbalance was coming down.
  12. The building companies’ original tenders had been based on a provisional bill of quantities and only about 50 or 60 drawings per site. But when they came to carry out the construction work they had to deal with thousands of drawings from the architects and a continuous procession of building instructions to deal with issues big and small which occurred as problems were encountered in turning ideas into practice. At one point it was estimated that Chamberlin Powell and Bon were so swamped that they were six weeks behind in responding to problems with new drawings.
  13. A major practical construction problem arose from the use of exposed concrete walls. There were tolerances of only 1/8 of an inch on walls 30 feet in length. Since door frames were all pre-made with no architraves around them, there were no tolerances at all on them. Window frames also had very small tolerances. The builders were not used to this. When using bricks and plaster there is considerable flexibility in dealing with tolerances or covering up ‘bodges’ with plaster. You only have to look at the precise holes for lift buttons in the Barbican Centre to see how exact every measurement had to be.
  14. To carry out the Barbican development Chamberlin Powell and Bon split their operation into two offices: one for the Barbican Centre under Charles Greenberg, and subsequently John Honer; the other office for the rest of the estate under Christof Bon.
  15. St Giles Cripplegate, which mostly dates from 1545–50, was half-ruined by aerial bombing during the War. Chamberlin Powell and Bon proposed that it should be used as an occasional concert hall, with practice rooms for the Guildhall School of Music and Drama attached to it. Instead, the church was restored as a working church in 1960 to designs by Godfrey Allen.
  16. The only pieces of history finding their way into the new development (apart from the church itself) were fragments of the City Wall and grave slabs from St Giles’s churchyard. The walls may have started out as Roman but the bits that survive are mainly medieval, and they were mainly exposed from below road level. Grave slabs from the former graveyard were fixed into raised tiled sections in the new podium terrace around the church.
  17. The terrace blocks were constructed on pile foundations deep into the London clay. They must have done something innovative where buildings were built over the new railway tunnels.
  18. There was concern that the construction of the foundations of the Barbican buildings might affect the water table of St Paul’s Cathedral. They carried out investigations and found that there were no streams going through the site towards St Paul’s which might be stopped or diverted. But then they also worried that water extracted for construction might affect the cathedral, creating settlement problems like houses after a drought. I guess the structural engineers must have worked it all out.
  19. The floor of the podium consists of large slabs, each about 150 ft². To avoid them crashing together like tectonic plates when temperature changes caused them to expand, they are all separated by expansion joints – what they call structural discontinuities – which are rendered watertight by the use of flexible water bars. I guess these are the strips of blackened rubber with their broken ends sticking you which you can sometimes notice when crossing the podium.
  20. The terraces were constructed using the cross wall construction system. It’s not the outside walls which form the structure, but the inner walls – the walls between flats or between flats and staircases. That’s why the living room windows of flats can be completely made of timber and glass from side to side and from floor to ceiling. The depth (front to back) of the terrace blocks stretched crosswall construction to the limits. They had to supplement the crosswalls with huge beams of concrete, six foot high, right along the façades of the blocks at every floor level. You don’t know what I am talking about? That’s because, incredibly, they are invisible to us. They are those innocuous little walls on which the window boxes are placed. In fact, of course, those ‘little’ walls go right down to the ceiling of the flat below.
  21. The City Corporation arranged for a stock of wooden railings, like the side of a playpen, to be available to occupiers with small children. These could be bolted into the sliding door openings of flats to prevent children gaining access to the balconies. (I don’t know if these are still available today.)
  22. There were British Rail and London Underground lines running under the Barbican area, mainly from Barbican station (or Aldersgate and Barbican station as it was then called) to Moorgate station. They couldn’t exactly cut these off for the decade while they built the estate. But the existing rail lines ran in a kind of curve like a bow, so what they did was construct a completely new tunnel in a straight line, like the string of a bow, and then just join the ends up when everything was ready.
  23. The potential noise and vibration from railway and underground lines running under the estate was a potential problem. But the structural engineers were optimistic about it because they’d had the same problem under the Royal Festival Hall and solved it. One solution employed was for the tracks to be laid on rubber devices to reduce the vibration, and these seem to have been generally successful, although there are some flats where you can feel a distant rumble occasionally.
  24. The columns were created in situ by pouring sections at a time within cylindrical containers. Something had to be done to “decorate” them, or else they would have looked like columns of bamboo as each section was added on top of the previous one. (You can still see the bamboo-like effect if you look carefully at some columns. The solution was pick hammering the finished columns which succeeded in more-or-less obscuring the bamboo effect.
  25. The architects said that they had chosen the concrete “so that some degree of weathering produces an acceptable patina rather than objectionable discolouration”. I guess the jury is probably still out on that one. However, remember that the original plans for the exteriors were for polished concrete and white tiles. I fear that would have ended up looking like an extremely discoloured toilet pan. So, I’m content with the water-stained concrete look.
  26. Architects just have to get philosophical. “The tiles, they said, were intended to be the colour of earth, so as to form a visual transition in colour and texture between the natural colours of grass, trees and plants and the stone grey of the buildings. Not only is it transitional visually, but it is transitional technologically – between the natural and man-made world – and historically – between the Old City and the Barbican”. They really could lay it on with a trowel, and that’s of course how the tiles were laid as well.
  27. Only your kitchen tap has drinking water, not your bathroom tap. Each block has tanks containing thousands of gallons of water to allow us to run baths and flush toilets. But you can’t use that to drink. Drinking water has to come from the mains direct. However, the “head” of mains water – how far it will rise on its own – is 100 feet in the Barbican. So boosted mains were necessary to get drinkable water up to flats above that height.