Tiling to gypsum based substrates/backgrounds.

[widler]

I always thought folk on here,dave especially , were into using the right materials for the right job ???
I could be wrong but i don't think skim plaster is the same chemical compound as anhyldrite screeds ??
Again i could be wrong , but why now bring out a 'gypsum' addy for gypsum screeds when we have been tiling gypsum walls, which according to some is exactly the same stuff as anhydrite ?
Im just throwing that into the mix as well [emoji15]

 

[peteablard]

The weber products I use give instructions for tiling over anhydrite screeds which IMO mean they are suitable. If they weren't suitable they would say Not for use on anhydrite or words to that effect.

 

[Stef]

The weber products I use give instructions for tiling over anhydrite screeds which IMO mean they are suitable. If they weren't suitable they would say Not for use on anhydrite or words to that effect.

Yeah Pete, it states on the back of all weber powder addy.

 

[Stef]

I always thought folk on here,dave especially , were into using the right materials for the right job ???
I could be wrong but i don't think skim plaster is the same chemical compound as anhyldrite screeds ??
Again i could be wrong , but why now bring out a 'gypsum' addy for gypsum screeds when we have been tiling gypsum walls, which according to some is exactly the same stuff as anhydrite ?
Im just throwing that into the mix as well [emoji15]

Think we need Alan to jump into this thread. [emoji6]

 

[Tile seller]

Looks like there's two ways of tiling over anhydrite screeds then,simple as that.

The big adhesive companies have there own science labs, and if they say you can prime first, then use a cement based adhesive on bases such as plaster and anhydrite (which both contain gypsum), then that's all I need to go on. where else are we to get our information? I choose to go with what's been scientifically proven to be able to recommend the correct products for given jobs.

 

[Just Rizzle]

do you guys know that weber do a anhidrite addy but only in FRANCE

 

[Just Rizzle]

anhydrite floors are here to stay and becoming more and more used . its vastly different to wall based gypsum as we all should know. theres never been any problems with skim plaster but the impurities in the floor products is what reacts with cement based adhesives and virtually no reaction to anhydrite based products. why risk it?

 

[Ajax123]

Think we need Alan to jump into this thread. [emoji6]

Nope... I'm enjoying reading it too much. My opinions are well known but when all is said and done Dave is right if you do it all by the book you can use cement addy. The gypsum addys remove the uncertainty and cater for the less perfect. Yes I know all tilers are great and do everything by the book...I have met many who have said so and yet the floors have failed. For my money why take the risk. Sand it, heat it, cool it, test it, prime it, and tile it but use gypsum based adhesive not cement.."...

 

[Dave]

You have to have a little chuckle at widler ...lol lol..


My point isn't about what should and shouldn't be used , it's if you tile to any gypsum based background , should you be using fypsum adhesive or is it one for floors and anything for walls lol..


Ray ! .. You still haven't answered my question ?


thanks for chipping in Alan , I and many many others know your views and yes we know all about switching to gypsum adhesives for anhydrite screeds , I'm asking , should they be using it on skimmed walls as well , after all in the words of another member , if you use cement based adhesives on gypsum backgrounds , you are ALWAYS got to get a reaction.

 

[Ajax123]

No need usually for gypsum adhesives on skimmed walls as long as they are primed. There's not enough moisture borne sulphate ions to promote an adverse ettringite reaction. It's all about balances and checks and molarity etc. in short you are unlikely to get much ettringite on a skimmed wall.

 

[Lee@emctiles]

valid points being made [MENTION=43777]DavidHoweTiling[/MENTION]

I dont know a fixer that comes in here that uses Anhyfix on walls......

and i agree about the forum......i just wished everyone of the tilers that come in here would read some of the posts......

everyday is a school day.

 

[Ian]

If anhyfix came in a slow set, I probably would use it on skimmed walls, however, it wouldn't be much use in wet areas so if I were doing a shower room I'd need 2 different adhesive types for the walls, and that's just a pain!

 

[Just Rizzle]

on my post on the other thread I ment to say gypsum based substrate floors so dave I never ment to bring in walls as theres no problem with them. as you all should know there is a very vast difference between floor based gypsum and walls that's why so many people are having failures on the floor not using appropriate adhesives and techniques and they need to know how to prevent this happening in the future. and the best way to do that is by using like for like on the floors

 

[peteablard]

I've heard of floors failing with gypsum based adhesives because the prep work hasn't been done right and that's what it always boils down to. If you know how to prep the floor correctly then you should never have a problem

 

[widler]

You have to have a little chuckle at widler ...lol lol..


My point isn't about what should and shouldn't be used , it's if you tile to any gypsum based background , should you be using fypsum adhesive or is it one for floors and anything for walls lol..


Ray ! .. You still haven't answered my question ?


thanks for chipping in Alan , I and many many others know your views and yes we know all about switching to gypsum adhesives for anhydrite screeds , I'm asking , should they be using it on skimmed walls as well , after all in the words of another member , if you use cement based adhesives on gypsum backgrounds , you are ALWAYS got to get a reaction.

That's what I come on for dave, a chuckle , you gotta laugh mate [emoji23][emoji23]

 

[Just Rizzle]

i have always used cement based but so far all screeds have been heated , I have one to do very soon and its unheated
, so I'm going to use Anhyfix as it allows that extra % of moisture in the screed , just incase lol...

walls ? , well as usual I use cement based..

you've never used anhyfix dave that supprises me. you will be in for an education .

 

[Dave]

you've never used anhyfix dave that supprises me. you will be in for an education .

All the the floors I have done Ray are for the same builder and he refuses to change from a method we have used and works before these gypsum adhesives came about .

the floor I am using Anhyfix on is one of my own , hence giving it a go.

So did you never use cement based on an anhydrite then Ray ? , you still haven't said.

 

[Dave]

No need usually for gypsum adhesives on skimmed walls as long as they are primed. There's not enough moisture borne sulphate ions to promote an adverse ettringite reaction. It's all about balances and checks and molarity etc. in short you are unlikely to get much ettringite on a skimmed wall.

That was my next point when someone said they had used it on walls as it isn't suitable for wet areas , bahhhh you've spoilt it now :lol:

 

[Rookery]

I'm curious as to why if anhydrite screeds are the bees knees and gypsum/anhydrite-based adhesives are the way forward, why don't BAL or Mapei make one?

 

[Just Rizzle]

dave how can you comment on these adhesives when as you say you've never used them??

and im well aware of what can be used in wet areas about 4yrs ago did 45 wet rooms for a builder on a site in Richmond

and no I use tilemaster products on walls as theres a vast difference between gypsum walls and anhydrite(calsium sulphate) floors as ajax123 asjust stated

 

[Just Rizzle]

Nope... I'm enjoying reading it too much. My opinions are well known but when all is said and done Dave is right if you do it all by the book you can use cement addy. The gypsum addys remove the uncertainty and cater for the less perfect. Yes I know all tilers are great and do everything by the book...I have met many who have said so and yet the floors have failed. For my money why take the risk. Sand it, heat it, cool it, test it, prime it, and tile it but use gypsum based adhesive not cement.."...

ajax are you saying that those of us that use gypsum based addy are not as perfect as others????

 

[Ajax123]

I'm curious as to why if anhydrite screeds are the bees knees and gypsum/anhydrite-based adhesives are the way forward, why don't BAL or Mapei make one?

Mapei do. They just don't make it available in the UK for some reason. You'd have to ask them why.

 

[Ajax123]

ajax are you saying that those of us that use gypsum based addy are not as perfect as others????

Not at all. What I'm saying is that there are tilers out there who don't do things properly especially in terms of prep and moisture testing. Gypsum adhesives add a level of robustness that means that most of the time the get away with it. There is no excuse for not doing the job properly but you would be naive in the extreme to think that everyone does. If you don't prep right with cement adhesive it WILL fail, if you don't prep right with gypsum addy it might not.

I have ate seen several failures with gypsum addy but not anything like the same sort of level as with cement

 

[Just Rizzle]

I'm curious as to why if anhydrite screeds are the bees knees and gypsum/anhydrite-based adhesives are the way forward, why don't BAL or Mapei make one?

weber do one as well but again only in france

 

[Dave]

dave how can you comment on these adhesives when as you say you've never used them??

and im well aware of what can be used in wet areas about 4yrs ago did 45 wet rooms for a builder on a site in Richmond

and no I use tilemaster products on walls as theres a vast difference between gypsum walls and anhydrite(calsium sulphate) floors as ajax123 asjust stated

I havent commented on using it , I use primer and cement ,, can't you read lol lol ..

You seem to refuse to say whether you've tiled using cement based but hey ho who cares TBO..


I think the threads served its purpose ... Cheers all.

 

[Just Rizzle]

Not at all. What I'm saying is that there are tilers out there who don't do things properly especially in terms of prep and moisture testing. Gypsum adhesives add a level of robustness that means that most of the time the get away with it. There is no excuse for not doing the job properly but you would be naive in the extreme to think that everyone does. If you don't prep right with cement adhesive it WILL fail, if you don't prep right with gypsum addy it might not.

I have ate seen several failures with gypsum addy but not anything like the same sort of level as with cement

ajax can you explain why some are laying cs screeds thinner and thinner with ufh was reading a thread where the screed was 40 mm thick or thin most I do are 60 to 70 mm thick. surely the thinner the screed the weaker it is and the hotter it will get or not as ufh pipes are closer to the surface and how will this effect the expansion and contraction of the products stuck to it .

 

[Turkish tiler]

I use mapei keraflex White over 5 years now. This is what it says on tech sheet
Keraflex cement based adhesive and I used many Times on gypsum and anhydride screed
WHERE TO USE

Interior and exterior bonding of ceramic tiles (single- fired, double-fired, porcelain tiles, terracotta, klinker, etc.) stone materials and mosaics of every type on floors, walls and ceilings. Also suitable for spot bonding of insulating materials such as expanded polystyrene, rock and glass wool, Eraclit® (wood-cement panels), sound-deadening/reduction panels, etc.

Some application examples

• Bonding ceramic tiles (double fired, single fired, porcelain, clay tiles, klinker, etc.), stone materials and mosaics on the following substrates:
– cement or mortar wall renders;

– interior aerated concrete block walls;
– gypsum or anhydrite after having first applied Primer G; – gypsum board;
– underfloor heated installations;
– cement screeds, as long as they are sufficiently

cured and dry;
– interior painted walls, as long as the paint is firmly

 

[Ajax123]

ajax can you explain why some are laying cs screeds thinner and thinner with ufh was reading a thread where the screed was 40 mm thick or thin most I do are 60 to 70 mm thick. surely the thinner the screed the weaker it is and the hotter it will get or not as ufh pipes are closer to the surface and how will this effect the expansion and contraction of the products stuck to it .

We we are going even thinner than 40mm in some cases. It's all about efficiency. The thinner the screed is the lower the mass and faster the response the lower the required running temperatures. The lower the temperature the less energy is required. It doesn't follow that the thinner it is the weaker it is as we do things with the materials to increase strength and flexibility. Yes it may affect the thermal expansion and contraction of things stuck to it but that is not really our primary concern. The tiling industry will I hope catch up with developments as we are moving faster than they are in the UK generally speaking or perhaps more accurately we are moving in slightly different directions.

 

[Ajax123]

I use mapei keraflex White over 5 years now. This is what it says on tech sheet
Keraflex cement based adhesive and I used many Times on gypsum and anhydride screed
WHERE TO USE

Interior and exterior bonding of ceramic tiles (single- fired, double-fired, porcelain tiles, terracotta, klinker, etc.) stone materials and mosaics of every type on floors, walls and ceilings. Also suitable for spot bonding of insulating materials such as expanded polystyrene, rock and glass wool, Eraclit® (wood-cement panels), sound-deadening/reduction panels, etc.

Some application examples

• Bonding ceramic tiles (double fired, single fired, porcelain, clay tiles, klinker, etc.), stone materials and mosaics on the following substrates:
– cement or mortar wall renders;

– interior aerated concrete block walls;
– gypsum or anhydrite after having first applied Primer G; – gypsum board;
– underfloor heated installations;
– cement screeds, as long as they are sufficiently

cured and dry;
– interior painted walls, as long as the paint is firmly

i have unfortunately seen this type of system fail more times than I can count. The failures are often a result of excess residual moisture (no test having been done) or primer failure (due to inadequate prep). It's one of the reasons I don't recommend it personally. Obviously if it is done right it's fine but it so often is not. The gypsum based adhesives are far more tolerant to residual moisture.

 

[Just Rizzle]

We we are going even thinner than 40mm in some cases. It's all about efficiency. The thinner the screed is the lower the mass and faster the response the lower the required running temperatures. The lower the temperature the less energy is required. It doesn't follow that the thinner it is the weaker it is as we do things with the materials to increase strength and flexibility. Yes it may affect the thermal expansion and contraction of things stuck to it but that is not really our primary concern. The tiling industry will I hope catch up with developments as we are moving faster than they are in the UK generally speaking or perhaps more accurately we are moving in slightly different directions.

thanks ajax. so the thinner the screed , may effect thermal expansion and contraction so would you say there is a need for decoupling mats to avoid failures?