Damp or a leak ?

[gertygumdrops]

Hi all, I have recently fitted a new bathroom suite for a customer and sited the thermostatic shower on the shared wall with next door. The bathroom pre fitting was an absolute disgrace with cracked tiles, mildew and a leaking bath. 8 months later I have received a call from the customer saying that the next door neighbours are complaining that the shared wall is damp. The neighbours had decorated just before I started the refit and painted the adjoining wall, and sited a mirror on it. They have just noticed that the area on the back of the mirror is damp. I have asked them to leave the mirror off for a while to see what happens. The wall remained dry, but on placing the mirror back damp reappeared. My question is ; has anyone come across this before? I am loathed to start breaking into the wall to investigate a leaking pipe ( there were a couple of compression fittings used ), as I suspect it is still damp from years of use of the neglected bathroom. I have had a chat with the neighbour and told them to give it a couple more months to see if it settles down, but it is causing me concern in the meantime. Your help would be greatly appreciated.

 

[heinz57]

It's probably the mirror itself thats causing the problem, if it fits flush
to the wall then there is no room for the air to circulate and damp appears
after they have had hot showers, baths etc. Ive seen this in both bathrooms and even kitchens where dressers and other items have been moved to reveal a damp and mouldy patch. Im not saying there is not a problem only that this is a common cause especially in older properties, hope this helps!

 

[Puddle]

Would point to condensation(maybe warm wall from pipework and cold mirrror back or could be warm air in flat against cold,badly insulated wall) anyway would suggest they can replace mirror on wall ,if they wish,however but place spacers behind to allow air circulation or insulate back of mirror or both,but allowing air circulation at back of mirror shold be enough

 

[Bernie2]

The obviouse thing seems to be the mirror. If its not damp without the mirror, but damp with it. There doesn't seem to be much doubt.

 

[REDSAW]

abd the other thing is, as you will know,
never use comp fits where you cant service them eh?.