Hi, my sipplier suggests I check the VAT rate I should be charged for the the work he is providing. He suggests I may be eligible for the 5% rate as I'm going from a single pane to double glazed and overal low u. The job is manufacture and installation of new sliding box sashes into the existing casements. I've looked on HMRC site and got confused. Any advice if 5 or 20% is the correct rate welcome. Also what admin, if any needs doing first?