A wall is then built round the brackets. Then the finished treads are bolted in place. These treads can be of steel or Wooden or wood clad metal. Cantilever measures should be created by a structural engineer, to make sure that they remain horizontal and rigid with use eventually. In https://staircaseinspirations.weebly.com/blog/the-rise-of-cantilever-staircases-in-contemporary-homes