Tiling disaster. Dodgy grout?

[sam8364]

Hi,
About two and half years ago I tiled my bathroom - quick job when we moved in the house. After 18months we had the bathroom re-fitted and I re-tiles.

We used the same tiles with the same shower over the bath but invested in the recommeded power shower resistant, mould resistant grout.


After 10 months I noticed a tiles had come loose. Behind it I found a very damp wall. Close inspection of the grout found cracks and loose tiles all over. Having removed some of the tiles today I have found extensive black mould concentrated around areas of grout. There is also a off white mould growing like fine roots through the ridges in the adhesive. This later mould extends from a area of untreated (tiled over) soft wood forming the end of a stud wall. Untreated timber in this position was the result of a cowboy bathroom fitter.

Is is normal to find mould behing grout? Is this a failure of the grout? The only element that has changed from the previous tiling is the grout (i.e same make tiles, adhesive, same shower used in the same room).

I am going to strip back and dry out and the stud wall will be removed before retiling. Do I have anything to worry about in terms of mould re-growth etc?

Any thoughts greatfully received

Sam

 

[r896neo]

What did you tile onto? I assume plasterboard or ply? Tiles can not be relied upon to form a 100% waterproof barrier so either use aquapanel when you redo it or tank it or both.

 

[Richard C]

Only ever use quality trade adhesive & grout, not DIY shed stuff; it’s not cheap but with these products, you only get what you pay for. If it’s studwork, use cement tile backer board as a base not plasterboard or plywood unless you tank it; & studwork needs flexible adhesive/grout to tile.

Even the best water proof gout/adhesive is only water proof in the sense it won’t break down when wet, it is still porous! Only the even more expensive epoxy based products are impermeable so damp can still find its way through & destroy the plasterboard underneath & if there is any doubt about the quality/integrity of the adhesive, a festering mould growth will be the result; you need to get rid of all traces of mould before starting again.