Advice needed on tanking wall-to-ceiling and wall-to-shower tray joints

[schismatic]

Planning to tank my en-suite tomorrow, using the BAL WP1 waterproofing kit. The ceiling is existing painted plasterboard. Do I need to tape and treat the joints between wall and ceiling like I do for the corners?

My gut says no, as the WP1 can't be painted on etc after. Presumably if I don't tank them, then I can just finish with sealant to match the paint? I know some just caulk too.

Just checking I'm not making a daft decision!

Also, where the bottom of the wall meets the shower tray, do I waterproof that joint? I'm assuming if I do that half of the tape will overlap down onto the shower tray for the time being, with WP1 just being applied to the walls and not the tray itself. Then presumably I just cut the tape away after tiling?? Some advice on how you go about waterproofing that joint would be much appreciate!

 

[Flintstone]

Your right about the ceiling, as long as you tank to the shower head that's enough. Sealing to the tray is a debatable thiing, some do exactly as you have said as I do myself when I need to, but I prefer tanking before the tray goes in when possible or even if the tray is in but not siliconed I will tape the tray up and tank below the tray Line give it a good deal with silicone after .

 

[GoneGuy]

Same as @Localtiler.
You could always mark where edge of tile sits on tray and use masking tape to protect rest of tray from paint and drips

 

[Waluigi]

Personally I don’t tape the wall to tray joint. I’ll tank and then silicone on top of the tanking

If you can, tank the wall first you then bond the tray to the tanked wall with clear silicone. Clear sticks better than white or coloured.

 

[schismatic]

Thanks for the suggestions all, amazingly useful as usual. I’ve already sealed between bottom of the wall and the tray itself, so will have to tank over that. Planning to use masking tape to assist with how far onto the tray I go as suggested.

 

[Waluigi]

Bal might’ve changed the formula since I last used it but I specifically remember them saying that their tanking won’t stick to silicone. This is going back many years though.

 

[Flintstone]

No tanking is gonna stick to silicone

 

[Waluigi]

Yes, that’s why it’s best to silicone onto tanking.

 

[schismatic]

Hmm, I’ve got a dilemma then. I’ve alresdy siliconed between the tray and the bottom of the wall. Do you suggest I remove this silicone and replace with something else than I *can* tank (caulk??), or should I just apply the tanking to the wall only for now and rely on the silicone underneath as a water barrier (note that this will be behind tiles and a further line of sealant between bottom of tiles and the tray).

 

[widler]

I’d just tank down to the tray , not a fan of rapping the tape over the tray , I can peel any spilled tanking off a tray with ease , so imo sticking the tape on the tray is a weaker joint than silicone ,silicone is harder to peel off , tanking is made to protect the substrate in a shower area, whereas in a wet room it’s to stop leaks .
I’m sure some will disagree with me
(That’s when I tank )

 

[Waluigi]

Hmm, I’ve got a dilemma then. I’ve alresdy siliconed between the tray and the bottom of the wall. Do you suggest I remove this silicone and replace with something else than I *can* tank (caulk??), or should I just apply the tanking to the wall only for now and rely on the silicone underneath as a water barrier (note that this will be behind tiles and a further line of sealant between bottom of tiles and the tray).

You’ve got Hardiebacker on the walls right?

I’d lay a blade flat onto your tray and score through the silicone, then scrape the silicone off the wall with a scraper. Leave the silicone that’s between the tray and the wall. Then tank, then a bead of sealant on top. Hopefully that makes sense.

 

[widler]

You’ve got Hardiebacker on the walls right?

I’d lay a blade flat onto your tray and score through the silicone, then scrape the silicone off the wall with a scraper. Leave the silicone that’s between the tray and the wall. Then tank, then a bead of sealant on top. Hopefully that makes sense.

Why just take a mm or two of silicone off the wall , than tank, the silicone is doing the same as the tanking would

 

[Waluigi]

Yes and no.

For me personally I think it’s a better job to apply silicone to tanking rather than trying to tank next to or on top of silicone. For the reasons stated above.

 

[One Day]

I've seen too many cases where silicone (usually clear) degrades and debonds over time.
Far better to carefully bond a tape to the tray using something like Kerdi-fix / Wedi 610 (a good elastomeric adhesive) and then the tape into the tanking.
Personally, I think silicone should be seen as a cosmetic rather than a functional product in wet areas.

 

[Boggs]

I always seal round with either Sticks Like S**t or CT1, that way you can tank over it as it’s paintable.
Mask off round the tray about 5mm in, apply tanking and remove the tape.
Use 2mm spacers between tiles and tray and fill the gap with silicone when finished.

 

[Qwerty]

I use Marmox sealant or Ceresit FT101 on the wall tray join and then paint over with paint on membrane