Looking for a bit of advice please- we had a new kitchen extension, after a few weeks of using it- the concrete where the extension meets the house looked visibly damp- this area is where the old sink was located and pipe extenders have been laid to the new sink. At first we thought it might have been loose plumbing connections, plumber came and dug it up, and tightened the fittings. It started to dry, but after rain this weekend it started to get wet again. The water seems to be seeping through old pipework in floor. Plumber has ‘listened’ to mains and can’t hear leak (not convinced he has ) although it is strange that it started drying out then started leaking again. Any other suggestions on what this can be- builder is stumped and so are we.Any advice would be appreciated- not sure what to do next.