After noticing a decline in air quality following the renovation, I decided to remove a section of the parquet flooring. Underneath, I found a significant layer of dust and sand on the wooden beams. Beneath the beams, there's about 15 cm of debris and sand. The crawl space appears dry, but I need to investigate further. Below that, there's a thin layer of concrete separating my ground-floor apartment from the basement.
Would installing a plastic vapor barrier over the sand help resolve this issue?
