Unique Galvanised Steel Section Used In The Knauf Shaftwall System. The Knauf CT Stud is a galvanised steel section used in the Knauf Shaftwall system to allow quick and safe construction from one side with the minimum number of components. Characteristics Unique galvanised steel section Used within Knauf Shaftwall System Permits quick and safe construction from one side. Field of Application: ASTM Shaftwall System Compliance Compliance EN 14195 Scope of application Estimating Guide: 1.67 linear metres per m2 of Shaftwall (based on 600mm centres).