In traditional curtain wall systems silicone is applied at the interface of the transom and the mullion, as well as the connection of the interior gaskets. However, this silicone connection was not engineered to be durable, as it cannot facilitate any thermally or mechanically induced movement. In the Fassada H60 system there is a precast TPE end piece with specific injection openings for butyl polymer. This was specifically designed for robust performance. The geometry of the end piece allows some movement and flexibility without inducing significant shear stresses.