It was quite dampening to see my bto bathroom grout collapsing in between and under the tiles, since Wifey and I had barely moved into our flat a year ago.
The grout was crumbling at two spots and I thought to use the sharp corner of a metal ruler to prod those grout lines to check for the extent of the defect.
In short, there is too little thinset mortar under our bathroom tiles and the grout were crumbling into the crevice.
Furthermore, the abyss was swallowing water as we bathed, which means I’d better re-grout before the ceiling of the unit below starts peeling.
To sidetrack a bit, my brother-in-law is never one to wake early, let alone bathe in the morning. Yet of all days, the only day he chose to bathe early, over the 52 weekends he has stayed over, is the day I repaired my grout. Maddening.