Does a cement and sand covered wall need tanking?

[fandyman]

Hi,

I'm in a process of prepping before retiling my bathroom. I've stripped the old tiles with adhesive down to some old plaster (I think it is an old sand and cement coat). I've also installed the STS tile backing boards on the other wall where the new bath with a shower will go. See the photos attached.

Can anyone tell me whether I should be tanking the boarded/plastered corner area above the bath?

Will some special adhesive be needed or the standard wall and floor tile adhesive will do like the one below?

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Finally, if the tanking is needed, do I need to prime after tanking and if so what type of primer to use there?

Thanks in advance.

 

[J K Tiling Cornwall]

Hi, tanking the area is not essential but would be belt and braces. Most tanking kits come with a primer either acrylic or resin based is fine. Then tile directly to the tanking solution no need to prime again. Use a cement based adhesive, the no nonsense one is quite sandy and really quick setting so more wastage. A standard set will give more time. Also looking at the pics, if that bath has been fitted in place then it could do with the gap being filled with sanitary Silicon sealant. Hope it all goes well 👍

 

[fandyman]

Thanks a lot. Really appreciate your help

 

[fandyman]

One more question - would you tank below the line of the bath to the floor?

I have tanked slightly lower than the line of the bath and thinking of siliconing there so thought no need to go to the floor but wanted to double check.

Do you think Silicon is a good option to seal there or shall I use some specialist product?

Cheers

 

[J K Tiling Cornwall]

Hi, no need to tank it to the floor just below the bath line would be sufficient. A decent Silicon sealant is fine, Mapei, Dow Corning or BAL easier to work with and clean off than the hybrid sealants. 👍

 

[Bond]

Looks like a decent gap between wall and bath,l would be tempted to use expanding foam in the gap, trim and Silicon, then tile.

 

[fandyman]

Thanks a lot again. That really helped with the work. Appreciated

 

[Dave]

Thanks a lot again. That really helped with the work. Appreciated

Let us know how it goes and maybe post some pics as you progress and finish.