The guy from BAL reckons the subfloor is incorrect, 6mm ply and as a result of this and the fact that unsuitable adhesive and grout has been used, we;ve got movement in the floor and this is causing cracks in the grout lines. The bathroom floor and entrance floor, which has the same issue, are all having to be removed and refitted. Real bummer.
We didnt specify that the plasterboard should be tanked, nor did we specify grouts and adhesives. We believed we had a professional doing the job, which we now know wasnt the case. Until we had the issues we hadnt even heard of tanking. We have got a contractor coming in to finish and make good the bathroom refit and he is bringing a tiler in to sort out the floors and potentially wet areas. I'm pretty sure, given other issues we've uncovered that our contractor didnt tank the walls. We are so reluctant to redo the walls though, as we have got 2 areas to redo and the showers are in e.g. our ensuite and main bathroom as both were fitted by our first contractor. When the tiler comes we will discuss it with him and see what he reckons. The suggestion to remove grout to see whats below is a good idea and we'll discuss this with the tiler. If it all has to come off the walls and be redone, then so be it as I'd hate to be storing a major can of woop *** for later.
If only you could buy hindsight.....
Many thanks to all who have contributed. Sorry I havent replied but we've been trying to sort it all out.