Tanking and Tiling onto bonding/rough plaster?

[piper64]

I've posted this in the plastering forum as well as I'm not sure where the proper place would be for advice. ( turns out that post was removed because I was so naughty as to duplicate a post)

I doing up the bathroom - new tiles etc.

The old tiles in the bathroom are coming off reasonably easily, because the finish plaster is also falling off with them. I don't really know what was holding them up all this time.

Question is, I'm tanking this particular area for a shower so is it necessary to have the walls nicely, smoothly plastered before putting the tanking on? Could I not just put the tanking on top of the rough/bonding coat, which is solidly stuck to the wall?

I intend to tile the whole room, so it will be the same for the rest of the bathroom I expect, plaster coming off with the old tiles. Do I really need to have a smooth, finish coat of plaster in order to fix tiles onto the walls. Can I not just apply tile adhesive to the rough plaster?

Time is the major issue here, as the bathroom is used daily and is in uproar at the moment, so any additional delays ( getting a plaster in and waiting for it to go off....) are going to be a pain. No, it really is.

thanks

Read more: https://www.diynot.com/diy/threads/...removed-the-plaster-too.503076/#ixzz5G97BF0ds

 

[piper64]

ok, it seems that some say it's alright to tile onto it ( with a SBR primer first) some say not. So not recommended, but who's right?

 

[piper64]

Thanks for chipping in anyway chaps.......

 

[piper64]

Is this really such a dumb question to ask that no one will reply? I've trawled the web, this forum and the wider world and the advice/opinion is inconclusive.

-I've been told I CAN tile to the bonding, but PVA it first.
-I've read that SBR is to be used rather than PVA.
-I've been told that it should be re-skimmed, but I won't be able to put the porcelain tiles on ( each weighing 4kg) because the skim won't take it. Plasterboard is best in that case.
-I've been told that I can plasterboard it with battons or if space is limited ( which it is) then dot and dab.
-I've read that Aquapanel is better, but putting some frame fixers through the dab is advised. (I presume that this will apply to plasterboard too?)
-Some say that standard plasterboard is ok to use so long as it's treated with SBR and tanked. ( Both?)
-Some say ONLY use Aquapanel or HardieBacker.

In the shower area, I assume that whatever I use it needs to be tanked.

So far, I can only see that skimming is out.

It seems that I need to board the walls with PB or Aquapanel or HardieBacker. Can I dot and dab onto bonding plaster? Do I need to use the often mentioned SBR first?

I'm a DIYer, not a tradesman and don't pretend to be, but as this is a DIY forum, I would really like some advice from the experienced among us.

 

[piper64]

I even posted this on the plastering forum in order to get something from anyone that might have an insight. That post was removed due the rule about about 'not duplicating posts'. As it seems that there are no tilers out there with any advice and due to the forum policy, no plasterers will see it either, it's been a waste of my time.

Maybe you're all sat there thinking "bl00dy amateurs, they should pay for us pros to do it" is all I can say.

Thanks a bunch chaps.....really helpful.

 

[Gerrydelasel]

I can't answer much of your questions, but yes you can dot and dab onto bonding plaster without SBR.
Some fitters are obsessed with using hardibacker and tanking. Basically they want to make showers that are tighter than a submarine and just as difficult to dismantle. This is probably a good idea in a hotel or whatever, but in a residence it's overkill. Your shower won't be used by thousands of customers daily, and these days people change their bathrooms like they change their gender. Plasterboard with tanking is fine. (Millions of homes don't even have the tanking so meh!). You might enjoy this thread that argues the toss. https://www.diynot.com/diy/threads/...er-on-same-wall-bathroom.486529/#post-3963429
Personally I don't see any reason why you can't tile straight onto bonding plaster, after all it's not really any different from tiling onto a rough concrete subfloor, but I haven't done it ¯\_(ツ)_/¯

 

[piper64]

Thanks Gerry, I was starting to think my computer wasn't connected to the web!

You say that I CAN dot and dab on bonding without using SBR, so I guess that you have done it. I'm assuming that using SBR wouldn't cause any issues though if I wanted to do it as a cautionary measure against the bonding sucking moisture from the adhesive?

I have read many threads that I thought would help me but, as you say, they just seem to argue the toss over personal preferences.

Tiling onto the bonding would be prefered, as space is an issue for the shower area and the tray will has VERY litttle wiggle room. I would say that tiling onto a rough concrete floor is different in that there are no 'gravity issues', compared to tiling on walls.

Would I need to SBR the area and apply a tanking solution? Do they even work together? If not, then dot and dab is my only way forward. Then apply tanking to the PB.

The added issue for me is the weight of the tiles, they are 4kg each ( 600 x 300 porcelain). I'm starting to look at other 'lighter' tiles, but even ceramic tiles of similar size work out at 3.5kg each or so.

 

[Gerrydelasel]

I'm assuming that using SBR wouldn't cause any issues though

I wouldn't expect so. PVA solution would also be fine. Mainly you're just trying to seal any dust rather than protect against moisture suction -drywall adhesive doesn't suffer from this as much as skim plaster does.

I would say that tiling onto a rough concrete floor is different in that there are no 'gravity issues', compared to tiling on walls.

The gravity is the same whether it's bonding plaster or wall board... If anything I'd expect tile adhesive to grip bonding plaster better than board! But I'm only speculating.

Would I need to SBR the area and apply a tanking solution? Do they even work together? If not, then dot and dab is my only way forward. Then apply tanking to the PB.

I don't see why, and I've not heard of anyone doing both. SBR sounds like overkill to me, it's what you use on the outside render of your house, not for a shower. Doing a good grout job and silicone seal between the tiles and tray is more important, IMO.

 

[piper64]

Hi Gerry, thanks for coming back to me on this.

I've spoken to Everbuild about their SBR and it gets even more confusing. It can be used neat or diluted, up to the user, BUT using SBR prior to tiling depends on what the cement based tile adhesive manufacturers say. I assume there could be some reaction between the SBR and the adhesive. Every turn takes me back to another issue.

The bonding seems to be very soild, but I've read that it's no to good to tile onto because it can crumble. I've read that I can't tile onto skim because it won't take the weight, can't tile onto bonding because it may crumble....what do people actuallty tile onto these days?

Even 'waterproof' adhesive and grout isn't actually waterproof apparently, just water resistant.

It's all getting very confusing with so much information that conflicts with another.....(especially as I tiled around a bath about 25 years ago and the plaster was soft before I started, but in my ignorance I carried on. The tiles were still there over 10 years later when we sold the house.)

 

[lostinthelight]

Just to confuse things. Some tanking solutions come with a primer to use before hand which could well be an sbr product. I doubt it would be pva as its not waterproof.
litl

 

[piper64]

Confusion is par for the course it seems. I hadn't realised that a 'simple' bathroom do-up would give me such a headache. It's like a science.

Add into the mix a flooded bathroom and water running down the walls of the new kitchen because a '22mm copper pipe' installed circa 1946, turned out to be 21.5mm. I only wanted to cap it as it was redundant, but still connected to the circuit. Only found out the stop end wasn't as good a fit as it seemed when I applied some water pressure to the pipes, all held for 10 minutes then it flew off the end. The compression ring with it.

 

[piper64]

Now looking at 10mm PCS Deltaboards, having been assured by Tileflair that they are what I need. Can be dot and dabbed or fixed to studs. Lightweight but take upto 85kg m2.

 

[cdbe]

Strip back to bare brick/block, sand and cement render, tile. I personally don't understand this obsession with sticking sheets of cement onto questionable backgrounds.

 

[piper64]

It's an option if I wasn't trying to live around the mess, but I don't really see the need to do all that work when cement boards are available? I'm not just sticking the boards onto the wall, I'll be mechanically fixing the them too, belt and braces. It gives a quick, smooth surface to tile on. The emphasis on quick.

 

[Keithmac]

Don't go anywhere near PVA!.

Don't put anything under the tile that will lose it's integrity when wet.

I've tiled onto finish plaster and it's been fine for 10 years. Tiled onto bonding plaster as well but not in the bathroom (wet/ steam).

Putting a waterproof panel (dot and dab) plus extra fixings for belt and braces makes sense if you're hanging heavy tiles off it.

I've read that grout isn't totally waterproof so there is a slim chance of it finally hitting whatever the tile is mounted on, if that turns to mush then all your hard work is for nowt!.

Don't go near PVA..