Having built the block walls, we then had to get all the steelwork engineered (which involved meticulous measuring on my part – and only one small error!) and fixed in place so we could work on the roof.
Once the steels were up, we fixed 7m-long sheets of Kingspan Multideck permanent formwork to them, added rebars and a mesh before casting concrete on top to form the roof.
The whole process (fixing the steelwork and casting the concrete) took just over three days.
The roof structure is thin (just 200mm thick), but as the concrete binds onto the channels and ridges of the Kingspan Multideck sheets, it forms a very strong structure, making it the perfect base for our planned green roof and allotment area.
We were initially looking at using large hollowcore planks to form the roof, but these would have needed to be craned into position (not a good idea when we have some overhead high voltage cables).