Went to measure some toilets that have been down less than 10 years. Looks like bitumen or similar causing discoloration. Any thoughts or other ideas?
bitumen sounds like a sound assessment, needs pulling up to investigate further although think your first guess could be the right one
Looking at the photo,there seems to be a light clean patch towards the bottom of the picture which to me indicates the contamination is not from below otherwise the discolouration would be more evenly spread. In my experience it looks like it has been introduced from above, dirty water left to stain? try buffing it down with a black pad and see what happens? i could be wrong though!!
My first thought is the staining comes from above and comes from the residue of lying water and has accumulated over the years. I'm wondering if the cleaner areas are high spots which wouldn't hold water.
