Both my bathrooms are over an unfinished garage. The garage is insulated but there's no ceiling. Both toilets are seeping some moisture that just following the grout lines. It's just moist. Not puddles. And it's only on one side (both toilets). No leaks visible from looking in the garage ceiling where they are located. My husband decided to replace the wax ring on one of them, which was only a year old and when he pulled the toilet up there was no sign of a leak but he said the underneath up inside the toilet has condensation all in it. We are wondering if this because of our main floor being over an unfinished garage and the heat/cold differences? My only concern is that this constant moisture is eventually going to cause my grout to start cracking and breaking apart. Does this sound like it might be the issue?

there 'should' have been a vapor barrier

the toilet penetration is oft overlooked/ignored


set the toilet(s)

check carefully for leaks


spray LOW expansion foam from BELOW juuuust enough to seal penetration

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638