I went to look at a job tonight. It was a basement in a office building. They had floating LVT installed a while back. Now they are getting this white powdery substance ( efflorescence?) coming up between the seams. There is a black rubber back walk off mat that was placed over one area and there is moisture under the mat. I told him I thought the vinyl is trapping the moisture. I suggested maybe they should go with carpet as the moisture can escape. I mentioned carpet tiles but was wondering if a action backed carpet would allow the moisture escape better. Please share your thoughts.