Problematic Anhyrdrite floor! - Tile Advice

[Gazzer]

Hi Mark. Thanks for the info. The wood floor is not stuck to the screed, it is an engineered oak floating floor. The tile I lifted was hard to get up and broke into 3 pieces the first part leaving the adhesive on the screed rather than on the tile. The tile had adhesive on it level with the high part of the pattern. Never doing screeds again...not worth the worry...hardibacker or wedi boards all the way!!![/QUOTE]


Uh ?????

 

[Perfect Tiling]

Ajax. Literature says "the screed does not require grinding for subsequent floor coverings or vinyl application." Later on it also states "eliminates the need for subsequent grinding". Travertine floor will be heated but it is isolated just now so customer can't turn it on incase thermal shock is a cause.
Sir Ramic...what I meant was that if I do smaller rooms with flooring where I put down hardibacker or insulation boards for electric UFH I have never had a problem with loose tiles...ever. I could have made as much out of 4-5 standard rooms than what i get from this big job

 

[tommyzooom]

I recently lost a job, as I said it needed to be sanded, the screed Co. (Larsen) said it didn't. Homeowner was adament that it shouldn't be sanded, and implied I didn't know what I was talking about. I assume it has now been tiled on top of a heavy dusting of emulsion paint, as he had all the walls spray painted:mad2:

 

[Perfect Tiling]

Cheers Tommy...its a maze out there. This floor was nice and clean as it had been protected from paint etc. I knew about sanding but screed company and literature said not to...so I followed their instructions...printed ones so I have evidence I hope.

 

[DHTiling]

If the trav is solid and just the porcs came up after heating, then i think it is a strong possibility that it was heated to quickly.. if the heating was ran for 3 weeks then i doubt much moisture was left in the screed..

porcs will react a lot different to thermal shock than stone as porcs rely on polymers to hold the tiles where as stone with hold in the capillaries/structure of the stone backs.. so the thermal stress will make porcs pop easier if subjected to heat to fast as the adhesive would not be at full structural strength till at least 28 + days.

So don't be quick to blame moisture / sulphate delamination till you see how quick the floor was heated up.

 

[Ajax123]

Cheers Tommy...its a maze out there. This floor was nice and clean as it had been protected from paint etc. I knew about sanding but screed company and literature said not to...so I followed their instructions...printed ones so I have evidence I hope.

You do in my opinion. The advice, whilst it flies in the face of the industry guidelines, is manufacturer advice and as such they will stand or fall by it. This does assume that te lack of sanding is a major contributing factor. It might be nothing to do with it but you need to be prepared to be told by lots of "experts" that lack of sanding is the cause. Based on time scales and having read the thread fully my money is on moisture and thermal activity.

 

[Perfect Tiling]

Cheers Dave. The floor appears to have been heated up from 10 degrees to 20 degrees within days. As said earlier, when I left on Fri it was at 10...this morning it was at 20 (setting on air sensor stats) but they were moving in on Sat so it could have been done overnight. They also have the settings on a timer so it would not be a consistent temp but on in morn then off then on again at night.

 

[Mark S]

The wording can be confusing.
The 'skin or laitence' was a few years ago a distinct 'layer, or skin. The screeds manufactured now do not have the same characteristics, however it is still recommended to sand or abraide the surface to open the screed to allow for primer penetration and for a good key for the adhesives.
It is much the same with power floated concrete, no visible 'skin', but the surface is allways scabbled to allow for a good key.
I would always recommend, if in doubt, sand it.
I hope this experience has not totally put you off screeds

 

[bugs183]

Hiya Mark.
I think you'll find there are an a great deal of tilers put off by these screeds.
You've arrived on this Forum a bit late to witness a load of us guys trying to make sense of this system that has been forced upon us.
I took it upon myself to try and have a good go and get to the bottom of these screeds, and to be honest i've given up on them as they are NOT worth the risk for us end trades, or at least ones who really care about their finished product. I'll explain as well as possible:
I've been tiling over 20 years and i kinda know when to tile a floor on concrete that it will stay put,. I know the recommended drying times, the ideas behind adhesives and their performance, blah blah. I do a floor, I get paid and the customer and myself are happy, for years, as the floor does what it's supposed to, it's stayed put.
So along come these screeds, ''ooh this is flat, i dunno what it is but its nice to tile too."
"The builder poured it really fast and it can be tiled in a few days", great stuff, we think, he says it fine to tile to.
Then (having not tiled too many i may add),we actually find out it's not cement based but gypsum, ooh thats odd, why use gypsum for a floor as it's not waterproof??
So then further research shows the drying are nothing like the ones we've been told, and can and ARE even slower than cement screeds.
Then we hear of failures," you should have sanded", "no one told us", "oh you should use epoxy primers", "that's not what BAL say, they spec the same as cement based adhesives".

So back on the phone:
Moisture testing, conflicting conversations from EVERYONE. Lafarge are vague as too whom is responcible, and what method.
One method recommended by one guy is poo poo'ed by another. Testing manufacturers say they don't agree with recommended practise.

Preparation: Who is responcible for sanding, if it even needs it, some say it does, some not.

Adhesives: People like Bal say prime and cement based, other like Kerakoll etc say gypsum friendly, others gypsum based adhesives.
Weren't we taught NOT to use Gypsum based adhesives as they don't stick porcelain, hence the move to modify adhesives when porcelain came out ten years ago?

I've tested all these adhesives with very mixed and mainly unsatisfactory results. Most gypsum adhesives i found didn't stick well at all to porcelain, and then have to be put through the rigours of lateral expansion with underfloor heating.
The best i found was creative impressions GBTA, and it cost £750 to tile a 63m2 slate floor to anhydrite, twice as much as cement based.
How the hell do you quote well for that and then programme it into your schedule to allow the vaugeries of it's drying times???

I've found two ways to approach these screeds:
Sand, prime, GBTA, Ditra Mat and then cement based adhesives. And even then Schluter aren't too happy with Gysum adhesive and Ditra, and the customer is certainly not happy with the price.
The second way is too say, "sorry, i'm not tiling this".
So i have been FORCED by your cack screeds to stop doing a job that i like, and make money at, to change the way i work, simply because NO ONE is helping out us tilers, the dunces taking the flack at the end of the job.

I know Ajax will read this, and he is a legend, and he has tried. But i'm a tiler and i have no confidence in this system at the present time, i am not alone, and the nimber will grow as these failures happen more and more.

This site is having more and more posts from failures from this screed and it needs to be dealt with by the people selling the screeds.
Yes you've sold loads for years in Europe, then bring the standards over here NOW.
Rant over.

 

[Gazzer]

And ...Breathe ! :lol:

 

[Mark S]

Quite a rant, and it appears justified.
However, as you no doubt will gleen, Ajax and myself are singing from the same hymn sheet.
The wording from manufacturers is confusing and does not help. What I would say, that if there is good dialogue with all parties at an early stage, (before screeds are installed), and the floor finish type identified, then steps can be taken to ensure correct preparation methods are undertaken.
When the screed is correctly specified, ie thickness etc, and all aspects of drying are undertaken the screeds do work.
The argument over priming and cement based adhesives over Gypsum or similar one will rage on long after this thread, there is a good argument for both, and down to personall preference.
Some good dialogue would not go amiss!!

 

[bugs183]

Hiya, don't worry i'm not having a crazy rant, but I really feel that we are tilers are simply not being heard, and sorry to say this but your answer has only echoed the conversations i and may other have had or are having.
You and Ajax see the screed form a perspective that we don't.
On many jobs we get called in and are asked to tile a floor, it normally has already been proepared, the screeders are long gone, the builder isn't interested and the customer just wants their job done.
We rarely get to have any input before a job is done:
I did with a local builder, i recommended these floors and everyone has had dryind problems, he wants them all ripped out, i fell like a bit of a pudding.
They are not working as you expect.
We as tilers cannot afford to have dialogue over which adhesive to use, this is OUR jobs here being messed with, and it happening now,we need firm and qualified answers from you guys, that we trust.
If you want dialogue then get Mapei, Bal, Lafarge, Kerakoll etc and a handful of well meaning tilers to sit down in a room so we can be heard.

 

[Gazzer]

I am glad you acknowledge our issues Mark.
I reckon we have heard it all about these screeds but I dont think you will find many fans here, or soft flooring guys !
The problem arises not so much on the large jobs but the smaller jobs. Like a normal house floor. The builder is a general builder and is under pressure to get done on time and looking at costs, screeder comes along and says " Here mate have this, job done in 4 hours, jobs a good un! "
I havent seen one flat floor from this type of screed yet ! I have witnessed soft topping, hard topping. The client nor builder want to pay for special primers, moisture tests ( which in their self prove inconsistent) , They dont want to pay for sanding/abrading of floor "but screeder says its fast track mate " IS IT COCO !
I have just turned my 1st Gyvlon floor down this week as its being pushed too fast and no one will do it right....at the end of the day when it fails I know where the finger will point.

While we sit here trying to make head or tail out of which way to tackle these screeds, one thing is missing and thats info to the client....They are being sold screeds that they dont really need and not given all info only what suits the screeder.

 

[bugs183]

To add, i find it very odd that massive companies such as Mapei have not bought over their Adhesives from Europe that work and have been proven to work for years.
I understand there is a British Standard issue here, but surely it can be achieved and i would prefer that to a Sub Standard job that i feel i do onto these screeds.
I simply do not trust Bal and Mapeis recommendation to tile these screeds using an Acrylic primer such as APD and follow that with cement based adhesives.
Maybe you guys should set up a sample floor laid to you specifications, and get some tilers in to tile it, using all the 'approved' adhesives and priming methods. I think you'll quickly see why we've got a monk on over these screeds.

 

[Mark S]

Sir Ramic,
I do acknowledge there needs to be more dialogue.
As manufacturers of the binder that makes the screed we are not always in front of the customers/clients till after the screed is in, if there are still 'screeders' doing a half truth sales job, we need to be aware of this, something I'm sure Ajax will back me up on.
One of our main roles is the correct specification of the screed, thickness, and to assist with advice re preparation for floor finishes.
I would be happy to sit round a table to discuss how best to tackle these 'issues'.
There are 000's of m2 of Anhydrite screeds installed and floor finishes applied with a hitch, but all the failures get high profile!!