The construction sequence of a typical gable wall:
a row of 3m-high precast concrete insulated sandwich panels was installed by crane.
(At ground oor level the loadbearing inner leaf of each panel rests on a cast in-situ concrete boot beam);
a series of precast oor slabs (2.4m or 1,200mm wide and 810m span) was craned in, with edges bearing on the 150mm load-bearing inner leaf of the insulated sandwich panels. The 8mm-diameter reinforcing bars projecting from the tops of the precast panels were bent over and covered with structural screed topping to stitch the panel to the oor slab;
a firestop and dpc were fixed in the cavity and the dpc was dressed down;
the upper precast concrete insulated sandwich panels were craned in so each 150mm inner leaf would rest on the screed, exactly above the inner leaf.
The prefixed, threaded bolts projecting from the inner leaf of the panel below were fixed into shoes cast in the inner leaf of the panel above; this formed the panel-to-panel connection; and the sequence was repeated.
Because the precast elements could be craned in, the erection sequence was speedy and an early weatherproof enclosure was created to let following trades install plasterboard wall finishes, the underoor heating pipes in the screed and the composite timber/aluminium windows.
By Susan Dawson