Soem advice please. Our builder ordered beams incorrectly and decided to effect a ''botched installation'' by welding them on site rather than wait for the correct beams to be delivered. The beams were originally welded by a non-coded welder and all tested welds failed NDT. When the repair work was done (this time by a coded welder) the structure was changed by the addition of several plates (but no new beams). We have repeatedly asked for new drawings and calculations, but he is refusing to do this, saying that the Building Control Officer has signed off the installation - based on a loosely worded e-mail from the Structural Engineer saying that he has inspected the revised installation and ''has no comment to make''. Are we worrying un-necessarily, or should we be pressing the builder to get revised calculations and drawings prepared ?