Ditra on Anhydrite

[Gazzer]

I've got my 1st Anhydrite job coming up, and have to say, i'm pretty nervous! 180m of Travertine. Is there anything that i need to be aware of ,with regards to the Trav?

Cheers
Scott

What ever you do, a floor that size.....make sure you get it right !

 

[Mark S]

Can't believe this question keeps being asked,
Prep, sand/adbrade vac, prime if using cement based adhesives, we recommend gypsum compatible these days, Gypfix, Kerakoll, etc, much safer

 

[DHTiling]

Can't believe this question keeps being asked,
Prep, sand/adbrade vac, prime if using cement based adhesives, we recommend gypsum compatible these days, Gypfix, Kerakoll, etc, much safer

It's because some tilers are frightened of the word anhydrite . .

Do it right first time and they are easy.

 

[bugs183]

Can't believe this question keeps being asked,
Prep, sand/adbrade vac, prime if using cement based adhesives, we recommend gypsum compatible these days, Gypfix, Kerakoll, etc, much safer

No moisture testing Mark?
People ask as it's their business and they will be held responcible. These floors still have failures for all sorts of reasons, so i think it is prudent to ask, maybe a new product has appeared on the scene that this fella doesn't know about.
Until the tiling community have complete faith then you guys are going to have to put up with questions.
Has anyone come to a definitive answer to what to fix Ditra onto anhydrite yet?

 

[Mark S]

Bugs, of course test for moisture, its sometimes taken it for granted that this is a standard procedure.
Not a problem the questions being asked, I'd rather someone asks than plows straight in regardless.
There is a lot of development work going on to make gypsum compatibile adhesives, levellers etc, as these are launched etc we will put the info/data sheets on the forum.
I would much rather people understood and felt happier about tiling on anhydrite screeds

 

[The D]

it's because some tilers are frightened of the word anhydrite . .

Do it right first time and they are easy.

lmfao

 

[bugs183]

Bugs, of course test for moisture, its sometimes taken it for granted that this is a standard procedure.
Not a problem the questions being asked, I'd rather someone asks than plows straight in regardless.
There is a lot of development work going on to make gypsum compatibile adhesives, levellers etc, as these are launched etc we will put the info/data sheets on the forum.
I would much rather people understood and felt happier about tiling on anhydrite screeds

No offence Mark, and i agree with all the points you make here, but your previous post could be considered quite condescending towards the subject, it could just be me, but us tilers are sensitive souls! The thread is about checking out what to do and how to go about things, and you just batted the question away like we are idiots for still asking, see what i mean?? The two statements look like they could've been written by two different people.

I'm not here to start a row, i just think that as guys ARE still worried here, you fells really need to respect this and be aware that sweeping statements to experienced tradesmen here could ruffle a few feathers.
Many tilers still feel they are in the firing line, and still don't feel comfortable about the whole Anhydrite system and it's compatibility with the job it's supposed to be doing.

 

[DHTiling]

Well here is my take on it.

As a pro tiler you should know how to prep sand tile this type of screed , I spent a lot of time reading spec and feel comfortable tiling to them.

What is the hassle ?

 

[Ajax123]

Well here is my take on it.

As a pro tiler you should know how to prep sand tile this type of screed , I spent a lot of time reading spec and feel comfortable tiling to them.

What is the hassle ?

problem is Dave as I see it there has been so much rubbish spoken about these screeds in the past that people still have difficulty in sorting fact from fallacy. It is changing slowly as more tilers get more contact with the screeds as they become increasingly popular. As you say you have spent a lot of time looking at them and I have had many conversations with you about them in the past. That information has made you comfortable but many tilers still need reassurance but often get it from the wrong place. It is as you say though very simple generally as long as you follow the steps outlined in the flowchart posted atelier in the thread.

Dont know if this one is a heated screed or not but bear in mind if it is the steps mus include commissioning the heating system and as its trav an uncoupling membrane should be used.

my personal opinion is that you should avoid cement based adhesives on the screed and use a gypsum compatible adhesive to stick down the membrane. Then use a flexible cement based addy to stick the tiles to the mat.

 

[bugs183]

Hey Ajax!

Quote: my personal opinion is that you should avoid cement based adhesives on the screed and use a gypsum compatible adhesive to stick down the membrane. Then use a flexible cement based addy to stick the tiles to the mat.

This is the first time i seen any screed rep actually recommend this method, is this now common theory for these screeds for applying an uncoulping membrane, or just your personal opinion, i was uncertain as to the stance companies such as Schluter take on it, but i've always thought it was the best overall solution. The gypsum is compatible with the screed and the cement above is compatible with the tiles, especially porcelain.
I always uncouple over under floor heated screeds, wether stone or porcelain, i've seen 20mm thick stone broken by movement in doorways where the customer/builder refused to install control joints or use an uncoulpling membrane.

That method will satisfy the tilers, now we just need to get the screeders to put the expansion joints in the doorways as required, i've tiled a number of these screeds and not seen any joints added between doorways ever!!

-

 

[DHTiling]

See now I am ok with cement based adhesives.
It is all in the knowledge.

 

[Ajax123]

Hey Ajax!

Quote: my personal opinion is that you should avoid cement based adhesives on the screed and use a gypsum compatible adhesive to stick down the membrane. Then use a flexible cement based addy to stick the tiles to the mat.

This is the first time i seen any screed rep actually recommend this method, is this now common theory for these screeds for applying an uncoulping membrane, or just your personal opinion, i was uncertain as to the stance companies such as Schluter take on it, but i've always thought it was the best overall solution. The gypsum is compatible with the screed and the cement above is compatible with the tiles, especially porcelain.
I always uncouple over under floor heated screeds, wether stone or porcelain, i've seen 20mm thick stone broken by movement in doorways where the customer/builder refused to install control joints or use an uncoulpling membrane.

That method will satisfy the tilers, now we just need to get the screeders to put the expansion joints in the doorways as required, i've tiled a number of these screeds and not seen any joints added between doorways ever!!

-

no it's not common theory but if its a heated screed and its travertine the British standard recommends uncoupling regardless of the screed type.

 

[bugs183]

I'm aware of the travertine side of things, thats a given. I meant the actual use of gypsum based adhesive with n uncoupling membrane.

 

[Ajax123]

I'm aware of the travertine side of things, thats a given. I meant the actual use of gypsum based adhesive with n uncoupling membrane.

Ah right. Well no that is a personal opinion based on technical appraisal and experience tinged with a dose of common sense.

 

[bugs183]

Ah right. Well no that is a personal opinion based on technical appraisal and experience tinged with a dose of common sense.

Your quite right!
It's a shame we can't get Schluter to go along with it as well, it would make all this much better for everyone!!!
Anyway, pub time!

 

[The D]

Bugs, of course test for moisture, its sometimes taken it for granted that this is a standard procedure.
Not a problem the questions being asked, I'd rather someone asks than plows straight in regardless.
There is a lot of development work going on to make gypsum compatibile adhesives, levellers etc, as these are launched etc we will put the info/data sheets on the forum.
I would much rather people understood and felt happier about tiling on anhydrite screeds

So are you saying that the adhesives we use every day are not compatible ?????????????

 

[Ajax123]

So are you saying that the adhesives we use every day are not compatible ?????????????

Chemically speaking yes. Cement which is your everyday adhesive is n compatible for direct contact with gypsum. In order to manage this incompatibility you must use a primer. Trouble is the primers don't always get applied in suh a way as to be effective (evn when following manufacturers instructions I might add). Often the primers are lilies or water sensitive so if any moisture gets into the system I cn cause emulsification f the primer. If ou use cement based adhesives my recomendation would lay be I use n epoxy primer. Better still though remove n element of risk by getting rid of the primer and using gypsum compatible adhesive that an be used primer free. (Some cannot)

 

[Sean SML Tiling]

Chemically speaking yes. Cement which is your everyday adhesive is n compatible for direct contact with gypsum. In order to manage this incompatibility you must use a primer. Trouble is the primers don't always get applied in suh a way as to be effective (evn when following manufacturers instructions I might add). Often the primers are lilies or water sensitive so if any moisture gets into the system I cn cause emulsification f the primer. If ou use cement based adhesives my recomendation would lay be I use n epoxy primer. Better still though remove n element of risk by getting rid of the primer and using gypsum compatible adhesive that an be used primer free. (Some cannot)

Threads like these are excellent, so much knowledge is gained by just reading and understanding what is being said. Fair play ajax you know your stuff. Why dont u write a thread of exactly how to prep a anhydrate screed in the forum arms?

 

[Mark S]

Bang on Ajax, some water based acrylic primers are more susceptible to moisture and completely disappear or as you say emulsify, epoxy every time to create a barrier between gypsum and cement.
There needs to be more gypsum compatible adhesives /levellers on the market.

 

[DHTiling]

And better prices mark

 

[bugs183]

The prices are outragous, i used GBTA for a job and it worked out double the cost of cement based.

So really guys you are confirming what makes us nervous about this whole system, the cement and the gypsum are not compatible, yet we still getting specs from Bal and Mapei saying just to prime as normal, not a mention of Epoxy anywhere, change the spec and we are on very dodgy ground if there is a problem.

Gypsum based adhesives does seem the way to go, but these do not adhere as well to the tiles as modified cement based so we are back to the problems when porcelain was introduced.
There is still lots of science, and big words, but these do not make the system very inspiring confidence wise.

It just seems very blase of the adhesive companies to stick with a spec that could very easily lead to problems.

 

[Sean SML Tiling]

Ive never tiled onto this substrate but going off what you guys are sayis the method is
1-Check moisture
2-Remove film
3-hoover
4-prime using epoxy primer if using cement based adhesives
5-use gypsum based adhesive for uncoupling
6-use flexible cement based adhesive on top of uncoupling membrane

Anything ive missed out or in the wrong order?

 

[Gazzer]

Dont forget commissioning any UFH system before hand.

 

[Sean SML Tiling]

Good point.

 

[Mark S]

Smltiling, you got it + the commissioning of course
As for prices we at Gyvlon hope to launch our own brand adhesives in the near future, will advise when they are available, they will be gypsum compatible, and we will aim to be sensibly priced.
The big companies have always pushed the use of acrylic primers, but from experience there is much less risk using epoxy ones, not sure why they insist on acrylic as they all make epoxys,.

 

[Sean SML Tiling]

Id happily take a job on tomorrow without being scared I now know the process so if something fails I know it wouldn't be down to me fixing

 

[beanz]

Thanks for all the info Gents.. Very helpful!

Id happily take a job on tomorrow without being scared I now know the process so if something fails I know it wouldn't be down to me fixing

That's very easy to say, but as pointed out, the best fixing method isn't the method being recommended by a lot of the manufacturers, so if there IS a problem, i can almost guarantee it'll be on your head.

 

[Peter]

How do the gypsum adhesives deal with the fleece of the ditra? Noone will say for definite that the two won't reject each other.

 

[Ian]

How do the gypsum adhesives deal with the fleece of the ditra? Noone will say for definite that the two won't reject each other.

I haven't fixed ditra but, have fixed dural ci+ with a gypsum adhesive (creative impressions), and it stuck really well and I mean, really well!

 

[Mark S]

I am a firm believer that you should use products from 1 manufacturer, a 'system'. Ditra don't make adhesives, but are recognised as a brand leader, the 'hoover' of de-coupling membranes
If one of the major adhesive manufacturers, and I know they can, provide a spec for the full 'system' I would go with that.