Large Size Heavy Duty Box Pergola Complete DIY Kit, Quality Tanalised Timber.Heavy duty, large size timber Box Pergola DIY Kit, manufactured from high quality tanalised redwood timber treated to ensure a 10 year warranty for rot. This version is our range of larger sized box pergolas started at the request of our customers. We have a great selection of pergola's and gazebo's, see the full Timber Pergola and Gazebo Range, if you are after a more cost effective pergola our Standard Heavy Duty Range should give you what you need.