Sounds about right. I did a job for a local builder mate a bit ago, new garage/extension above. Did everything to the book, made sure joists were only drilled in correct places and dimensions, everything to the book. Got pulled up a bit ago by some young BCO lass for being 15mm outside of safe zone for an outside light, fair enough. Then the plumbers turn up, just hack the woodwork to bits and basically shove plastic pipework anywhere they fancy with no regard to weakening joists and running pipes 5mm from the surface that would be boarded over. What happened to the 50mm bit? AND they used plastic push fit joints in voids that would be inaccessible afterwards, I thought you were supposed to use copper and soldered joints in such circumstances? How can gas pipes just be installed anywhere the plumber fancies?? Keeps them in megabucks I suppose.