The external envelope consists of hundreds of interfacing surfaces of differing materials and constructions forming the upper floors alone. The co-ordinated design of these elements and their associated intersections proved a particular challenge. Difficulty in obtaining Local Authority responses, changes in Planning personnel and late input from the main contractor in respect of sub-contractor and supplier information all provided challenges which we dealt with successfully. A forced changed to a second main contractor half way through the build, the need for value engineering and other design changes demanded by the Client were also successfully navigated.