STS foam tiling board // tanking really necessary ?

[Evren]

Has anyone had first hand / long term experience with SBS foam boards for tiling ?

I am currently trying to tile a shower enclosure (3 walls)
Mainly due to uneven walls i have used 10mm STS tiling foam boards on all walls.
I am reading mixed views about priming and tanking these before tiling.

Firstly , I understand priming is to do with better adhesion of the tile to the board but aren`t these tiling boards meant to be tiles straight hence the price tag compared to plasterboard ,plywood etc?

Secondly , when you join 2 edges on the STS system you have to use the MEGA STRENGTH expanding foam type adhesive which goes hard like a glue while joining 2 edges together.
If water gets through the grout and behind the tile what could possibly happen ? go though the foam board layer into the foam and out the other end layer ?

Also if we are trying to stop water from getting through the grout , can i not just use a waterproof grout or seal the standard grout or use waterproof adhesive as well to stop water getting through ?



Apologies for million questions but i am trying not to overkill this thing and would like some real life experience /input on this.
People had shower cubicles for donkeys and they did survive without these massively overpriced tanking kits etc .

 

[mcprinter]

DIY

I used a different foam board that required joints/screws taped and tanked.
The STS replaces this with the Mega Strength adhesive.
You do not need to tank.

Presume you have seen the STS Tech Sheet? No need to prime STS before tiling.
Only place you would need to prime or SBR is solid walls before attaching the STS

https://media.wickes.co.uk/is/content/wickes/GPID_1100488308_TECH_0

Waterproofing wet areas makes sense. Either with a tanking kit or fully waterproof boards.
Tanking kit is £50. Not a great deal in the cost of a bathroom refurb.

I am sure I am not the only one that has removed water damaged plasterboard/plaster.
Things have moved on.

 

[Evren]

DIY

I used a different foam board that required joints/screws taped and tanked.
The STS replaces this with the Mega Strength adhesive.
You do not need to tank.

Presume you have seen the STS Tech Sheet? No need to prime STS before tiling.
Only place you would need to prime or SBR is solid walls before attaching the STS

https://media.wickes.co.uk/is/content/wickes/GPID_1100488308_TECH_0

Waterproofing wet areas makes sense. Either with a tanking kit or fully waterproof boards.
Tanking kit is £50. Not a great deal in the cost of a bathroom refurb.

I am sure I am not the only one that has removed water damaged plasterboard/plaster.
Things have moved on.

Thanks for your reply and clearing this up .

Yes i have seen the tech sheet before i decided on STS boards for this job but i had a chat with an SBS tech guy via their website today telling me i have to use a tanking system for peace of mind. I even for one minute doubted what i have read on that tech sheet long time ago (thanks for the link )
The guy disappeared before i could question any further .


I totaly agree and i am not being tight in terms of a tanking kit but i also live by the principle that if something is not broken dont fix it.

Any idea if the mega strength adhesive can be used for sealing the gaps between the shower valve and the STS board or shall i use something like PLUMBERS GOLD , Silicone ?

 

[mcprinter]

Not sure on the sealing to be honest. Not clear on the STS site.
Would probably go with a decent silicone.

 

[oldbutnotdead]

Tanking is belt braces and nailing it down. The costs in time and effort to fix any leak once the room is finished makes £50 for goo and tape a trivial expense.

 

[TeaAndBiscuits]

I used STS boards in one of my bathrooms - straight to the stud using the PU adhesive and stainless screws/those big washers.

I didn't tank anything - just used some patches of Impey Waterguard membrane I had laying around to cover the screws and washers, although I consider this to have been unnecessary/belt and braces.

CT1 or silicone between the bath and the wall and to seal around shower valves etc.

From experience you certainly don't need to prime for the sake of tile adhesion. Using cement based adhesive there's only one way the tiles will come off in the future - by taking the board with them.

 

[Evren]

On a different note I have slightly messed up the 90 degree between one of the short walls and the long one .
Its more like 93-94 degrees. In order to get the large tiles I have (30 x 75cm ) to sit at a 90 degree to the longer wall i need to back butter one end a lot.(20mm)
I can see on the tile adhesive instructions that i cant go over 10mm bedding though .

Can i however build up the STS foam board with a coat of adhesive (10mm) then tile over this tile adhesive after it is fully cured and dried ?
Would the dried /cured adhesive need to be primed before it can be tiled over ?

Any ideas / experience on this please ?

 

[oldbutnotdead]

4 degrees isn't slight! If you're using powder tile glue you can put a render coat (or whatever you want to call it) on to build up the low spot, let it go off, tile as normal.
Remember whatever line you set you will have to carry up to ceiling height and full width of the short wall otherwise it'll look odd (especially in the corner)

EDIT 4° out over a metre is about 70mm- a significant oops

 

[Evren]

4 degrees isn't slight! If you're using powder tile glue you can put a render coat (or whatever you want to call it) on to build up the low spot, let it go off, tile as normal.
Remember whatever line you set you will have to carry up to ceiling height and full width of the short wall otherwise it'll look odd (especially in the corner)

EDIT 4° out over a metre is about 70mm- a significant oops

Thank you , so i don`t have to seal /primer tile adhesive


To be honest i am not sure how many degrees it is exactly
But over that 75cm width of the tile it makes a around 10-12mm difference in depth between the ends (roughly )

 

[oldbutnotdead]

Thank you , so i don`t have to seal /primer tile adhesive


To be honest i am not sure how many degrees it is exactly
But over that 75cm width of the tile it makes a around 10-12mm difference in depth between the ends (roughly )

That's only 1.5 ° or so. Is your narrow wall only 1 tile wide?- if not you'll need to go a bit deeper on the corner fill

 

[Evren]

That's only 1.5 ° or so. Is your narrow wall only 1 tile wide?- if not you'll need to go a bit deeper on the corner fill

Hi yes only 1 tile wide ,longer wall is 120cm wide.