The 14 trusses, fabricated and installed by specialist sub-contractor Severfield, varied in weight between 40 tonnes and 71 tonnes, with the total coming in at just over 700 tonnes.
Three elevations have bolted connections between the truss sections with 600 bolts per connection, while the fourth elevation has welded connections that provide a 28 metre clear span between the ground floor columns.
They have required a 500-tonne mobile crane situated at three separate locations to lift into place and have just been installed over a period of three weeks. One of the locations for the crane was the ground floor slab above a two storey basement, which required significant temporary back propping.
To allow the welding to be undertaken on the front elevation, the truss sections were installed on temporary trestles with hydraulic jacks used to level them in position. The welding was completed in 7 days working around the clock to maintain heat in the steel. 
Project manager Declan Galvin said, “It’s a huge exercise, and you won’t conduct something like this often in your career. It’s gone very well and has been a BAM team effort as BAM Design produced the structural detail design, with temporary works designed by BAM Technical Services and installed by BAM Plant.”

Declan Galvin

Project manager

Mick Kelly, the construction director overseeing the zone B schemes delivered by BAM’s South East team, says that work is on schedule on both the £80 million Eric Parry-designed building and its £60 million neighbour, B6 (3 Pancras Square) designed by Porphyrios Associates,  and being project managed by Geoff Hall, which is due to hand over next July. BAM Design is engaged and developing both schemes from stage 3.