Tanking on new plaster

[Kitsune]

Hi
Do you have to wait four weeks before you can tank and then tile on new plaster, the BAL WP1 data sheet states that new plaster must be at least 4 weeks old before tiling.
My other half does not think tanking is necessary unless you are doing a wet room (we are doing a shower with tray) and definitely won't wait that long as we don't currently have a bathroom. Plaster (skim) is a week and a half old.

I have been looking into tanking and have a few strange questions as well. I can see that it protects the wall that is tanked but how does it help with leaks. I thought leaks often happened around the edges where the tray meets the wall or where the screens are, if you have a shower tray is it only the walls which are tanked, our tray has already been fitted so we couldn't do the floor. Also if water can get through the grout and behind your tiles can it still do some damage even with tanking, such as find it's way down to the floor, or will it be trapped by the adhesive?

Thanks

 

[Paul C.]

A couple of answers for you. The plaster will depend on the thickness. If it is a skim onto another surface, you only need to leave it for 48 hours. If it is thick plaster going over brick or render then yes you do need to leave it longer. If it is tiled too soon, you are locking in the moisture an not allowing it to fully cure and strengthen.

If your shower tray is already installed, the tanking tape can overlap it, so that any leaks from the wall will flow in. However if you have 100% coverage of adhesive, that will prevent the moisture and condensation having anywhere to go. None of this will stop leaks behind the tanking.... that would be down to a plumber to make sure that doesn't happen. Same with the floor underneath. If you were able to temporarily remove the tray, you could also tank the floor and put a collar around the drain outlet and reinstall the tray over the top, but like your other half says, it is mainly designed for wet rooms. So in my opinion, tanking the floor under a tray would be a bit overkill and the benefits of this would be somewhere between non-existent and minimal.

Although tanking is highly recommended on the wall. The adhesive and grouts are water resistant, so water can still get through to the plaster if you don't. Get a small lump of dried plaster, leave it in a bucket of water and see what happens. It will eventually soften, break down and become extremely weak.... I'd rather that happen in a bucket of water than on walls of a shower which are holding up £X's of tiles.

Problems with leaks can happen anywhere in a shower, but tanking will eliminate one of the biggest issues.

 

[joe-90]

Waterproof grouts are waterproof. They'd be in breach of the 'Sale of Goods Act' if they weren't.

 

[Paul C.]

Hmmm..... Ok.

Think someone needs to read the small-print, or better still the Technical Data Sheets. We've tested waterproof properties on grouts and adhesives before. The only TRUE waterproof grout we tested was epoxy resin. But even if I was using that in a shower, I would still tank it because its the right thing to do.

Joe, here is just one example. I think you should have a read of this and then tell me that "Waterproof" grout is really waterproof! Might be in SOME conditions, but not all.... Also says on the front it can fix porcelain.... but on the back "only if its 200x200 or less". This is an example of how they can advertise something but not necessarily need to cover all bases. Don't be suckered in or take anything at face value.

http://www.mapei.com/public/GB/products/2711_waterprooffixgrout_uk.pdf

Quote from page 2.... "Water RESISTANCE - Good"...... Not excellent??? why not I hear you ask....... Its only waterproof if it is only intermittently splashed in small amounts of water.

Need any more examples?

 

[joe-90]

Yes please.

 

[Paul C.]

Unibond..... claims to be waterproof on the tub.....

Then on their website, fails to mention Waterproof as a Product feature, and states below, suitable for Intermittently wet areas.... which agreed, a shower is. But a shower is a little more than intermittent don't you think? It can have water sitting on it for god knows how long and not to mention the steam and condensation. It then goes into the realms of having the same resistance properties as a fishing net or standard cement based grout.......



Next one's an adhesive: Dunlop Waterproof tile adhesive (clues in the title what they claim it to be.)

But read this and repeat parts 2,3 and 4 of the important information..... the bit where it can't be used in swimming pools or areas of standing water. You tell me why not? ITS WATERPROOF ISN'T IT?, and why do they still recommend tanking?

http://www.dunloptrade.com/wp-content/uploads/2015/09/TDS-Waterproof-wall-tile-adhesive.pdf



So thats just two more examples. Why was tanking invented if all anyone needs is waterproof grout?

Actually, if you want to hear another farse...... The term "Anti-Mould" and "Mould Resistant". Mould can still grow over the top of it and people complain when it does.... but what these terms actually mean, is that mould can't grow IN it or penetrate it.

Not having a go or anything but its food for thought. Never heard of problems for any jobs that have been tanked. But have heard of plenty gone wrong that haven't. Personally I'd never trust the word "waterproof" on any grout or adhesive. Its all very careful and very clever advertising.

 

[joe-90]

A shower is intermittent wet. It's not like a swimming pool. If it says suitable for wet rooms and permanently wet areas then that's what it is for. If you use a bed of waterproof adhesive and not dot and dab and a waterproof grout, then you won't get any problems.

 

[Paul C.]

He's wrong, but i give up arguing. I've been in the tiling industry for 18 years and obviously still have no clue as to what I'm talking about.

 

[joe-90]

Never mind mate.

 

[Paul C.]

From the man who in a previous thread said dotting and dabbing tiles on a wonky wall was ok to level it?

Peace

 

[Paul C.]

QUICK TURN AROUND, LOOOOOOK...... YOU COULDN'T EVEN TIE YOUR HORSE UP PROPERLY!

Sorry, couldn't resist

 

[joe-90]

As long as it's not inside the shower cubicle it is. Are you really a tiler?

 

[Paul C.]

Not any more. Now I'm an independent technical advisor/assessor. And you are a [job description here]?

 

[joe-90]

I can see why you got booted off the tools. Now you're a jobsworth. Typical.

 

[Paul C.]

Step too far mate. You have no idea the reason I am no longer tiling. What makes you think I was booted off? As for the jobsworth comment, you really haven't got a clue.

You can make whatever assumptions you like, but I take pride in my job. And if there is one thing that winds me up, its have'a'go heroes that think they know what they're doing, leaving they're customers out pocket because of bad workmanship and bad advise.

Sorry Kitsune, this has gone slightly off topic. But you have two lots of advice. The choice is yours on how you proceed. I hope we've managed to provide you with some entertainment.