Porous grout lets water behind tiles and marks when wet

[ggodart]

I've just had my bathroom tiled by a 'professional tiler' and now when the wall gets wet the water penetrates through the grout and into the tiles which then shows up as a dark mark.
The tiler is blaming the tiles, they are cheap DIY ones unfortunately and the glaze does not go around the edges very far, this is made worse by his grout which doesn't lie flush with the surface everywhere. How do you suggest I fix this, get him to dig the grout out and do it again, or will a 'tile and grout' seal do the trick?
Thanks

 

[DHTiling]

Hello and welcome..

Do you know make of tile, make of grout .. and some pics would help of the grouting.

 

[Mike Mike]

Cementious materials, like grout, allow water to penetrate them. That is a law of chemistry. It doesn't matter if it says "waterproof grout" on the packet, the only truly waterproof grout is epoxy resin, which is used in hospitals and restaurant kitchens, but costs about 4 times more per m2 to have installed than your tiles cost.

Please upload a photo of the tiling, and a close-up if possible of a tile where the grout is sitting below the glaze on the edge of the tile, if indeed it is. The fact that it isn't sitting flush with the surface of the tile is irrelevant, it shouldn't do, especially if they have any sort of bevel, otherwise the grout lines would look about 10mm wide, which would look unacceptable.

A tile sealer will not stop water penetrating the grout. Nothing will, except epoxy resin grout.

 

[Diamond Pool Finishers]

and that also go's for adhesive render/screed , great point Swed

 

[Brian the Tile]

totally agree with Sweedish Mike,most grouts are only water resistant and there is a big difference between that and waterproof grout who supplied the materials?phone him ask his advice if he is a pro tiler i wouldnt imagine he would leave you in the lurch so to speak, give him a chance first,but then again if you have used cheap tiles adhesive and grout well i tend to feel a bit for the tiler as you cant make a silk purse out of a pigs ear

 

[Billy Hunt]

Some of the cheaper red biscuit tiles are prone to this i'm afraid,bar regrouting with epoxy can't see any solution TBH.
It shouldn't have any long term issues with the tiles as they should dry out as normal when not wetted.
I assume the tiler has tanked the area?