Hanson Birchwood put 18 months' effort into coming up with the design for a three storey precast concrete staircase for St James Homes. The housebuilder wanted a sound absorbing concrete version of staircases that had previously been constructed on another site in timber. This called for a combination of L and U shaped stair flights in plan, incorporating winders and finished with a smooth curved and winding soffit.
The apparently simple brief produced a problem that was best solved using one-piece, storey height, flights. Even when the computer generated image suggested a solution was possible some of the string sections looked so slim that there were concerns the stair flight may be too fragile to manufacture and transport.
A one eighth scale wooden model of the flight was made to gain confidence in the workability of the design. This was followed by a full scale mould of the most compicated section. Go ahead was given after 18 months of trial designs, experimental moulds and 3D modelling.