Myths and Misunderstandings: Testing the water resistance of grout - TilersForums.com

[The D]

ok so i have started this thread because of a conversation between me and dan in another thread about the performance of grout and tanking systems in a wet area. i am not trying to be disrespectful or anything like that i just want the correct information bothe for me and the general public. I have been tiling a long time and like to think i keep myself up to date with as much technical information as my tiny tilers brain will allow me to store but now my understanding of how grout and tanking systems work has been questioned, so i think its time to put it to the test.


this is the post that inspired the test from a thread called Help! Tiled wetroom floor looks perfect but grout doesn't dry out!.

OP Dan
( You're misunderstanding the word 'waterproof' if you think a tiled wall or floor is impervious to water, surely?


EVERY bathroom wall that's not tanked, fails eventually due to the substrate getting wet constantly when it hasn't been tanked. EVERY bathroom wall that's been tanked, and properly using tape onto the bath or shower tray, NEVER fails due to water ingress.


So the tiles are literally never protecting the substrate from water and are literally just there to take the brunt of the 'weathering' (term used loosely) and cleaning and to give the room an aesthetically pleasing look.


Not meant to come across argumentative BTW.)


the test will be to see how long the grout will resist the water. I will tile the inside of a cardboard box and grout it with standord non modifid wall grout leave it to dry for one week then fill it with water i will let the water sit in the box for as long as it takes for the water to completely penetrate the grout and soak the cardboard background.


l would appreciate any comments and suggestions all input on this thread is welcome.

 

[widler]

good idea deano, I've only just stated tanking , and only wet rooms , never had a substrat fail either, and I've tiled hundreds of showers.
I think if a shower is tiled right, it shouldn't need re doing un5il a customer wants it changing ,re siliconing yes, but not retiling .

 

[Dave]

There's a difference from occasional wetting , to full on submersion .

Grout WILL allow the passage of water when fully submersed for long periods but if occasional wetting , say like a wetroom floor , then it will take longer for the wetting to seep through .

Tanking is a fail safe protecting the substrate , the tiles and grout offer the initial protection which in turn is backed up by tanking , be it membrane or paste.

Your test isn't really what would happen in a wetroom floor though , as a wetroom floor wouldn't be fully immersed in water for days on end.

But I see what you are trying to point out

 

[Andy Allen]

Won't the moisture from the adhesive turn the cardboard box to mush...

 

[Ajax123]

I suspect more bathrooms fail as a result of bad corners than bad grout. That said grout is porous up less treated with an additive to make it not so. They won't be as porous as say a screed as the particle size and thus the packing density is better, assuming it's mixed and applied correctly. As Dave says occasional wetting e.g. A shower would be very different to a swimming pool. My bathroom was tiled 20 years ago using premixed tubbed waterprof tile adhesive and grout. It has never been an issue despite no tanking apart from at the corners where the tiles met the bath. Silicone failure and thus damp bottom row tiles occurred.

 

[The D]

rapid set i think will be ok and it will have a week to dry

 

[Spare Tool]

I've recently had a tanked shower over a bath fail, water running down the porch wall downstairs..without removing all the bottom row of tiles(which my customer didn't want to do) fixed it by resiliconing. It's hard to say exactly how it failed but my gut feeling is the tape that was overlipped onto the bath must have come unstuck from the bath when its been filled plus weight of a body.. are you supposed to fill the bath completely as you would before siliconing, before applying the tape and tanking paint? if I remember right it was a tilemaster kit..

 

[AliGage]

I saw the thread you mention deano and stayed out of it.
Are you tanking part of the box?

It's no a realistic scenario test. Complete submersion of water and it'll pass the grout in a couple of hours.

I felt both of you were correct in areas of the other topic.

Cementitious grout is not waterproof
Modern day grouts resist water (repellant)
Your tiled surface is your protection from water.
Tanking ensures inevitable penetration of water doesn't deteriorate the substrate.

But as far as shower areas go. Mild to heavy usage not an awful lot if moisture will penetrate the grout joints.Not sufficiently enough to do real damage as such. Gravity pays a huge part.

Tanking gives an installation longevity but I wouldn't of said we use it to direct water to Drainage Like I think was being suggested in the other thread.

Keen to see results of your test though

 

[The D]

I saw the thread you mention deano and stayed out of it.
Are you tanking part of the box?

It's no a realistic scenario test. Complete submersion of water and it'll pass the grout in a couple of hours.

I felt both of you were correct in areas of the other topic.

Cementitious grout is not waterproof
Modern day grouts resist water (repellant)
Your tiled surface is your protection from water.
Tanking ensures inevitable penetration of water doesn't deteriorate the substrate.

But as far as shower areas go. Mild to heavy usage not an awful lot if moisture will penetrate the grout joints.Not sufficiently enough to do real damage as such. Gravity pays a huge part.

Tanking gives an installation longevity but I wouldn't of said we use it to direct water to Drainage Like I think was being suggested in the other thread.

Keen to see results of your test though

i was thinking weeks not a couple of hours. but we will see i'm Keen to see the results myself

 

[AliGage]

Well I could be wrong. Thinking about it a "couple" of hours would be very quick. Bur in the other hand this is complete submersion.
The speed in which it penetrates would depend on a few factors regarding grout choice. Could be good to explore this a little more testing different, common and popular brands?

But Im quite confident thinking there'll be signs within a 24 hour period certainly.

Interesting and in a small way, an exciting topic/test deano!

 

[John Benton]

Regarding the length of time for the water to penetrate the grout I saw this test when I went on the DryTreat sealer course. 2 'cups' made out of grout approx 20mm thick, one left without any sealer and one treated with Drytreat. They were then filled with water and the untreated one lasted about 30 minutes before the water was visible and the bottom of the cup.

 

[The D]

wow 30 minutes that's fast

 

[John Benton]

That's exactly what I thought Deano. Bearing in mind the grout joint is only as deep as the tile and if 4 people use the shower consecutively that could quite easily be 1/2 hour in total. That's why I now tank showers over baths as well.

 

[Rizzle from the Portizzle]

hi dean i am with you on this tanking in your every day bathroom is a waste of money .when i fixed tiles in bathrooms shower rooms in the old days .i would run a bead of silcon down the courners and base before i started tiling then fix my tiles into the wet silcon so it was always behind the tiles and could never peel off now grout then resilcon on the top so when the client could see the silcon on the out side peeling it was not to late as the silcon behind was still holding the water back .so if you have time dean silcon one up first lay the tiles into it wet then do the other with no silcon behind the results should be intresting as the weight of water will be greatested at its loading points bottom courners only real tilers ask the right questions the rest just pay for there ignornce

 

[AliGage]

Please don't take this the wrong way @Ray TT @ Porcel-Thin but I would assume hot water systems, shower valves and such have changed somewhat since.
The sheer volume of water in a 10 minute shower these days is far amount greater.