Need for tanking on shower walls

Discussion in 'Tilers' Talk' started by Duncan Forsyth, Jun 7, 2019.

  1. Duncan Forsyth

    Duncan Forsyth New Member

    I am currently discussing with my tile fitters the need for tanking on my shower walls. The walls are stud walls lined with plasterboard, which has been skimmed. I am thinking that these walls require tanking before tiling since grout is not waterproof, and either is the adhesive, nor the substrate.

    My fitters tell me that tanking is not required because I have a shower tray, but I can't understand how the tray prevents water seeping through the grout on the walls, which are almost continuously wet, and damaging the substrate beneath.

    Could someone settle this debate, please?

  2. LEH

    LEH Active Member

    See here:

    I would also be sure that your tiles (+adhesive) are not too heavy for a skimmed wall - these can only take 20 kg/m2. Normally you would just fix to the plasterboard as this has a higher weight loading, or a specific tile backer board. Was it skimmed specifically for the job or was the wall already like that. If they skimmed it, I'd maybe find another tiler, doesn't sound like they know what they're doing.
  3. MalcyB

    MalcyB Member

    I would get some one who knows what they are doing. Seems to me you know more about it than they do.
    Tanking should be done in a shower area.
  4. CGN

    CGN Well-Known Member

    Generally tank all shower cubicles. A kit costs £40 so a no brainier.
    rogerk101 likes this.
  5. Mr Rusty

    Mr Rusty Well-Known Member

    +1. Always tank pb. Why wouldn't You? As others gave said watch the loading.
    CGN likes this.
  6. Duncan Forsyth

    Duncan Forsyth New Member

    Thanks for all your responses.

    I chose 10mm marble tiles for covering the bulk of the walls. I am now thinking that these are too heavy for the skimmed walls. What do you think?
  7. LEH

    LEH Active Member

  8. RL424

    RL424 New Member

    Hi, I'm in a similar position looking for some advice on preparation. Looking to tile around 3 sides of a bath with a wall mounted shower. Currently the surface is a plasterboard stud wall with a skim over the top, which has been repaired in patches where damaged from removing the old tiles. I understand I'll need to be careful with the weight when choosing the tiles. But for preparation I understand I need to apply a tanking but do I need to apply any primer before/after the tanking?

    Also I will be tiling the floor (outside of the bath) and was going to use fix a 6mm aqua board over the floorboards tape/tank the joints but does this also need any primer or can I just go straight on with the adhesive.

  9. LEH

    LEH Active Member

    For tanking: pick a product and then follow manufacturer's instructions. It depends - Mapei kit you prime first, Ardex for example, you don't, you just apply two different mixes.

    For tiling onto cement boards, you don't technically need to prime, as both board and adhesive are cement-based (cement and gypsum i.e. plasterboard do not mix). However, you'd be better off priming anyway, as it stops the board sucking the water out of your adhesive super fast, which can make it harder to get a good bond.
  10. RL424

    RL424 New Member

    Thanks for the reply LEH.

    So does this mean I should be using a different adhesive for the tiles on the walls after tanking? I was intending on using 'Mapei Mapeker Rapid Set Flexible Tile Adhesive' for both applications?
  11. LEH

    LEH Active Member

    No you're fine, primer/tanking is a barrier between the two, so you're sticking onto the coating not the plasterboard. I'd go for a standard set tile adhesive though, e.g. Mapei Keraflex Maxi S1. Pros would use rapid set for the floor (because you can walk on faster), but for a DIYer you will find it less stressful and waste less adhesive by using a slow set :)
  12. Neil Thakore

    Neil Thakore New Member

    Waterproofing has long been a recommendation for commercial areas, but under new BS 5385-1:2018 its now a requirement for domestic areas too. Ardex have a great product called WPC Rapid drying coating.
    Its a two part product, at the moment it also comes with scrim tape for the corners and a free roller sleeve. The great thing about this product against the rest is you can tile after 90 mins.

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