The situation is that I have a 9 inch (230mm) retaining block wall where the lane height at the rear is higher than the yard wall, We are up to dpc with my extension and when my building inspector came this morning to check is advising us to pass the 1200g visqueen that will be under the new floor, to run up the inner wall to dpc and take it right through the cavity and through to the outer wall and up along the outer block wall in the cavity between the retaining wall and the outer wall. He ten wants this continuous visqueen run to rise up to the lane level go right back through the outer extension wall and cavity to the outside of the inner wall and the run up to doc level above the lane level back through the inner wall at lane doc level. My builder just does not agree with this. Is anyone still burning the midnight oil ...like me 'cos it's driving me nuts!