PVC Columns bring a very different look to a pergola. PVC Columns may be reinforced with aluminum or with VFI's Steel Insert System (US Patent #8061106) for Columns. In ground or concrete pad installation options. Videos are available for the installation of a 13' x 11' Structural Pergola using columns. Click on Part 1: Setting the Posts, Part 2: Assembling the Columns, or Part 3: Assembling the Pergola Top to view instructions.