Hope this is the right place, so a bathroom fitter did this. 100mm diameter, cut with a 70mm saw but took a few goes presumably due to the 40mm pipe being fussy. 200mm depth joist and 2800mm length. I believe that the horizontal location is ok, however the diameter simply couldn't ever be. Over in the plumbing forum a plumber suggested that a joiner would be the right person to get an idea whether or not it can be repaired and how? Any suggestions?
Many thanks
Many thanks