anhydrite

[AD Ceramics]

Hi Guys

Just had the rep from Mapei out today to spec for 60m² 800x800 tiling to a kitchen on to anhydrite screed, never tiled on to an [FONT=Arial, Helvetica, sans-serif]anhydrite screed always steered clear of them, what would you use to sand the floor for the best results? he specified Mapei primer T after sanding as many coats before it stopped soaking in and kerraquid with latex plus additive, I still plan on using Ditra matting with it being a heated screed and I am thinking if I do get an area of de lamination the Ditra may help it survive.[/FONT]
[FONT=Arial, Helvetica, sans-serif]He recommended that a damp test is carried out prior to installation, the only problem is the owner of the company I work for is rush, rush, rush and whilst he will damp test it I don't think it will dry in time for my installation date of January 6th and the heating will be fired up the week after the screed has been installed, the screed is only being installed this Thursday 12th (omg that's means it's Friday 13th day after)
Any advise or info you guys could offer would be great, another company I sub to has had every anhydrite floor tiled failed by their previous tiler hence they no longer use that product for their floors.

Regards

Paul[/FONT]

 

[Stef]

I'm very surprised Mapei said a test had to be done.
I spoke to technical & they told me that's only for wood & carpet floor coverings nothing to do with tiles as moisture can escape through the grout lines..
Lots of info on here. Personally I would contact lee @ Tiletown & order some AnhyFix as its a gypsum adhesive specifically designed for these screeds..

 

[Ian]

3 weeks is nowhere near enough time to dry fully even with the heating on IMO. Adhesive wise, use anhyfix from tilemaster, it's gypsum compatible and designed specifically for these screeds.

 

[Chalker]

Floor needs to be dry, Heating needs to be tested and all this before jan, and screed not been laid yet!
try and educate your boss, buy I'm guessing he will make you do it anyway.
Disaster waiting to happen.
i know we don't live in a perfect world, but a builder I sub to works from the kitchen install backwards. Ie date for kitchen install, less testing heating, less drying time. This gives a latest date for screed to go in.

 

[Stef]

What depth is the screed going in at?
I use a drum floor sander for these screeds, hire it from Jewsons for a day.

I set a hygrometer on a floor this morning (Gyvlon) so I can get a reading for the end of the week.
This screed was poured at 55mm about 7/8 weeks ago & has been sanded & blasted with heat for a few weeks & it will be lucky if its ready to accept tiles.
There is no chance that an anhydrite screed will be ready at the start of January.

 

[Ajax123]

I'm very surprised Mapei said a test had to be done.
I spoke to technical & they told me that's only for wood & carpet floor coverings nothing to do with tiles as moisture can escape through the grout lines.. 
Lots of info on here. Personally I would contact lee @ Tiletown & order some AnhyFix as its a gypsum adhesive specifically designed for these screeds..

WTF!!! All screeds should be tested for moisture before tiling....

 

[Ajax123]

It will not be dry enough to tile by 6th jan if it's only going in tomorrow unless it is properly force dried using the underfloor heating at high temperature coupled with plenty of ventilation or extraction.

 

[Stef]

WTF!!! All screeds should be tested for moisture before tiling....

Alan do you not remember me posting this before when I was looking for advise months ago?
Straight from Mapei technical help line.
Spoke to Mark Simpson at Gyvlon & he was just as shocked..

 

[Rich Midge]

Steer clear of this one, protect your reputation. If it fails, which sounds likely given the time its got to dry, the blame almost always comes back on the tiler.

 

[Ajax123]

No need to steer clear. Just wait for it to dry before tiling.

 

[Rich Midge]

Apologies, what I meant was don't be pressured into doing the job if its not ready. If the builder/client is willing to wait for the screed to fully cure then that's obviously the way to go.

 

[Lee@emctiles]

On a project at the moment where Gypsol screed has been fitted, 7 weeks or so ago, client had excellent advise all the way from Alan and Mark@tilemaster. Floor was forced dried, tested and now being tiled using TM Anhyfix. Tilers comment on site yesterday "had to get a tile up that didnt quite look right.......it was a b%£ch to get up"

AD follow the advice from the people who know what they are doing.

 

[Mark S]

Like Ajax said why avoid, use the UFH to dry the screed, it has to be commissioned prior to tiling anyway.
Not sure again why mapei say no need to test, test every floor before applying a floor finish,
I would go with a gypsum compatible adhesive as well.

 

[AD Ceramics]

On a project at the moment where Gypsol screed has been fitted, 7 weeks or so ago, client had excellent advise all the way from Alan and Mark@tilemaster. Floor was forced dried, tested and now being tiled using TM Anhyfix. Tilers comment on site yesterday "had to get a tile up that didnt quite look right.......it was a b%£ch to get up"

AD follow the advice from the people who know what they are doing.

I made an enquiry tonight with one of my suppliers regarding a gypsum based adhesive and they said there product will just go straight onto the screed, he never said anything about sanding or priming, I would never stick a tile on a any type of floor without priming, strange how they never mentioned priming to such a problematic substrate, and no mention of sanding!!!!!! any thoughts on that as I assumed the sanding was the most important first stage of installation.

 

[Gazzer]

I made an enquiry tonight with one of my suppliers regarding a gypsum based adhesive and they said there product will just go straight onto the screed, he never said anything about sanding or priming, I would never stick a tile on a any type of floor without priming, strange how they never mentioned priming to such a problematic substrate, and no mention of sanding!!!!!! any thoughts on that as I assumed the sanding was the most important first stage of installation.

Perhaps they dont know anything !

 

[Ian]

Perhaps they dont know anything !

No perhaps about it. More bad advice from people who should know better.

 

[Ajax123]

I made an enquiry tonight with one of my suppliers regarding a gypsum based adhesive and they said there product will just go straight onto the screed, he never said anything about sanding or priming, I would never stick a tile on a any type of floor without priming, strange how they never mentioned priming to such a problematic substrate, and no mention of sanding!!!!!! any thoughts on that as I assumed the sanding was the most important first stage of installation.

There are adhesives that do not require a primer but there are none that remove the need for sanding. Which adhesive was it?

 

[Mark S]

Even after all these years, Gyvlon entered the UK market in 1996!! there are still people saying utter c**p about the screed, the preparation, drying times etc etc,.
All I can say is if in doubt ask !!, we are here to help and ensure successful installation of foremost the screed but the floor finish as well.

 

[AD Ceramics]

There are adhesives that do not require a primer but there are none that remove the need for sanding. Which adhesive was it?

Hi Ajax123

The adhesive that has been recommended to me is Keracol H40 Eco ideal, no primer just floor abraded and hoovered, now the word abraded would that suggest sanding, when I said scabbled oh no no no that's not good enough so abraded it is, what would you recommend to abrade the surface.
Would you install a ditra or similar anti fracture mat with an 800x800 tile, I normally wouldn't hesitate to use ditra but it has been suggested that it doesn't need it, I beg to differ but thought I would ask you guys, have any of you heard of decomat pro matting, any good?

Cheers guys

Paul

 

[Ajax123]

Hi Ajax123

The adhesive that has been recommended to me is Keracol H40 Eco ideal, no primer just floor abraded and hoovered, now the word abraded would that suggest sanding, when I said scabbled oh no no no that's not good enough so abraded it is, what would you recommend to abrade the surface.
Would you install a ditra or similar anti fracture mat with an 800x800 tile, I normally wouldn't hesitate to use ditra but it has been suggested that it doesn't need it, I beg to differ but thought I would ask you guys, have any of you heard of decomat pro matting, any good?

Cheers guys

Paul

sanding and not scrabbling. Scrabbling is for concrete not screeds. So sand with medium grit paper or 60grit to remove any loose and friable material and damn good vacuum to get rid of the dust. H 40 Eco ideal is perfectly ok with no primer. If the screed is very porous or dusty then a consolidating primer might not do any harm. Would only use decoupler if it is heated and natural stone but with 800x800 it's up to you. It can't do any harm but is probably over engineered. If it natural stone then decoupling is essential.

 

[Gazzer]

I use a floor polisher with sanding disc, works a treat and does not create too much airborne dust due to its low rpm speed.

 

[AD Ceramics]

Would only use decoupler if it is heated and natural stone but with 800x800 it's up to you. It can't do any harm but is probably over engineered. If it natural stone then decoupling is essential.

yes it is heated and porcelain tiles.

 

[Mark S]

Check with Kerakoll, as they have an adhesive specifically for latge format tiles.
H40 is 'Ideal' for ceramics onto Gyvlon screeds, without the need to prime, although some still prime but only to prevent the adhesive drying too quickly.
As with the other posts sand using an orbital type STR machine and 60-7-grit paper, to remove any loose or friable surface material, and to open up the screed surface.
And deffo use a de-coupling membrane

 

[Stef]

Took readings from the hygrometer today,

This Gyvlon was 55mm deep & this is day 53.
Good to go me thinks.
Working right through the holidays.