Please Define 'Fully Tanked' - Is This Acceptable?

[Terry1977]

I recently had my new bathroom installed which included a 1200x800 shower area. However, after several months the a hairline crack developed within the tiles and a leak developed. This particular wall is a solid wall which sits directly on a joist. It is likely that movement within the joist has caused the hairline crack.

The bathroom fitter initially quoted for concrete backer boards to be fitted in the wet area and the wet area to be 'fully tanked'.

However, concrete backer boards were only installed on one wall and the wall that failed was sealed with aqua defence direct on to bonding which was subsequently tiled over.

Does this constitute 'fully tanked' or should concrete backer boards have been fitted to the entirety of the wet area?

Please let me know your thoughts.

Regards,

Terry

 

[opps]

AFAIK, you should not tile over bonding plaster regardless of tanking.

It might be advisable to contact Mapei. I suspect that at a minimum they recommend sealing the bonding before applying Aquadefence.

I tile from time to time but I get really hacked of with tilers that I see on site that use cement based adhesives directly over plaster (not something that your tiler did but all plaster should be sealed to prevent ettringite crystals forming). I guess that most of them don't want to turn up, apply primer (SBR/etc) and wait for it to dry overnight before tiling. Get in, whack the tiles up, get paid and run away... (sorry, doesn't necessarily apply to your tiler).

 

[oldbutnotdead]

If your quote specified backer boards all round, why weren't they fitted? Did you agree to this variation? Did you get anything off the bill for reduced material and labour costs?

 

[Terry1977]

If your quote specified backer boards all round, why weren't they fitted? Did you agree to this variation? Did you get anything off the bill for reduced material and labour costs?

Yes, the quote specified backer boards all round. The variation was not agreed to. When questioned, the bathroom fitter's response was that the wall was already flat so the backer boards weren't necessary. Although the fracture in the grout could have been caused by the wall moving, the lack of backer board presumably could have been a contributing factor.

 

[oldbutnotdead]

Backer boards do a bit more than provide a flat surface. They insulate a bit (heat and noise). They don't fall to bits if they get damp. They can firm up a wall (so can any board for that matter). And they aren't free.
This failed grout- was it at a junction between walls? Usual sketch is to use silicon in the corners not grout for exactly this reason.
I'm assuming that your 'solid wall on a joist' is a masonry wall supported by the joist not just a joist at 90 degrees to the wall.

 

[Deleted member 292770]

tile backers wont stop flex in a joist that leads to movement in a block wall.

 

[oldbutnotdead]

tile backers wont stop flex in a joist that leads to movement in a block wall.

True. I was thinking more of half brick walls and lime mortar... still waiting to see whether this crack was in a corner