Grout gone black

boardtc

We tanked out bathroom with fibreglass and then laid tiles 6 months ago. We have found that the (grey) grout goes black. The tiler has even since skimmed off the top of the grout and reapplied but the same thing happens. He has never seen this before. Picture attached. Any ideas appreciated!

stephenmarr

possible leak running into grout

PK27

boardtc wrote: »

We tanked out bathroom with fibreglass and then laid tiles 6 months ago. We have found that the (grey) grout goes black. The tiler has even since skimmed off the top of the grout and reapplied but the same thing happens. He has never seen this before. Picture attached. Any ideas appreciated!

When he skimmed the top was it grey underneath or was it dark the whole way through? I assume if you've tanked the room then you have a wet room? Is there a glass panel on shower area or is the room entirely open? It's possible there's back falls on the room and water is getting under tiles. If you put a spirit level on the tiles there should be a fall into the drain from every direction. However, the tiler may have bedded the tiles to fall to drain, but the floor underneath may be falling the wrong way so if water gets under it will find the low points of the room and settle underneath. The mousture will then come up through the grout and make it appear dark.
Wet rooms are great in theory, but in an existing room with floors running off level built to abismal Irish standards they can cause problems , not always fitters fault!