Tiling to gypsum based substrates/backgrounds.

[Dave]

AnhyFix let's you tile at 85% RH but I still wait till my meter reads 75% or below.

Here's one for you Dave, I've a floor coming up & will more than likely have to slc certain bits as the screed is not great.
Would you prime & use a cement based slc to save some money?

Is this a gypsum screed stef ? If so , then I've not levelled one before , but I do know there are gypsum levellers now lol.. But as you say , if the screed is dry and primed correctly , then yes Imho a cement based slc would be fine.. But do we take the risk is another question ? 🙂

 

[Sean SML Tiling]

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..

After all the info on here my first anhydrite I went with anhyfix as the weber rep didn't give me any confidence on what was the correct method.

 

[Stef]

im in the mindset , that if you prep each job correctly be it walls to floor , then cement based works but if we start to,use gypsum addy , then really we should be using it on both wall and floors ...

It's a good marketing ploy though as the gypsum addy is a premium compared to cement based.
I've done one Gyvlon with a cement based addy & it failed but it was tiled in 7 days as the builder wanted clients moved in & his money & floor would get sorted at a later date.
I suppose this has always stuck in my mind even though I know why it failed, I've never had bother tiling to plaster so why should I have bother with a screed!!

 

[Dave]

After all the info on here my first anhydrite I went with anhyfix as the weber rep didn't give me any confidence on what was the correct method.

After past experiences with reps , I would not take a reps advice ever again lol.. Most are new to the game and TBO ain't got a clue.

 

[peteablard]

I have a builder I have worked for around 18 yrs and he's the same , I have tiled loads of anhydrite with cement based and ALL have been ok , so he sees no reason to change to such a relatively new product when what we use works fine .


my opinion is , we are being scare mongered into using new products and stating nothing else will suffice , when that isn't true.. Lol..

Thats pretty much word for word what my builder says. He's not daft and has done a lot of research about the different adhesives and I can't see him every changing from this method. I'm confident doing it this way and the builder always explains to the customer and the plumber about using the UFH the first time. I've got another one to tile for him in a few weeks when it's dry!

 

[Dave]

It's a good marketing ploy though as the gypsum addy is a premium compared to cement based.
I've done one Gyvlon with a cement based addy & it failed but it was tiled in 7 days as the builder wanted clients moved in & his money & floor would get sorted at a later date.
I suppose this has always stuck in my mind even though I know why it failed, I've never had bother tiling to plaster so why should I have bother with a screed!!

I bet that scared you some ...


the the problem is stef , with anhydrite being quite new to most of us , we are easily lead to believing the word of reps.

 

[Stef]

Is this a gypsum screed stef ? If so , then I've not levelled one before , but I do know there are gypsum levellers now lol.. But as you say , if the screed is dry and primed correctly , then yes Imho a cement based slc would be fine.. But do we take the risk is another question ? 🙂

Yeah, got told it was a Gyvlon but it's came from Bardons.
I recommended the company to come in & they made a pigs ear of it.
Doesn't look great for me, I've tiled a few of their screeds & they are normally perfect.
I've used Anhylevel on a floor & it's good stuff but the whole point in getting this screed laid was so it was flat & needed no extra prep!! [emoji35][emoji35]

 

[Sean SML Tiling]

Weber told me that it needed priming neat 1 way then diluted 3:1 the other and then use non flexI with the additive. The I was told that it was to be primed 4:1 both ways and then 2 part addy again. Then I was told 4:1 priming both ways and that flexible adhesive is to be used. How was I supposed to be confident going into this world of anhydrites with advice like this. I do agree with you if it's prepped properly with the moisture levels correct there shouldn't be any issues what adhesive is used.

 

[Stef]

I bet that scared you some ...


the the problem is stef , with anhydrite being quite new to most of us , we are easily lead to believing the word of reps.

I had already done my research & knew what the outcome was going to be so I was prepared for it.
Had a lengthy discussion with the builder but as usual some just see the ££ signs..

 

[Dave]

Weber told me that it needed priming neat 1 way then diluted 3:1 the other and then use non flexI with the additive. The I was told that it was to be primed 4:1 both ways and then 2 part addy again. Then I was told 4:1 priming both ways and that flexible adhesive is to be used. How was I supposed to be confident going into this world of anhydrites with advice like this. I do agree with you if it's prepped properly with the moisture levels correct there shouldn't be any issues what adhesive is used.

Thats mad :mad2:...

it it states on the pr360 bottle how to use it for anhydrite screeds... So why would a rep advise otherwise ffs.

pr360 is 4:1 and 4 to 5 coats allowing for drying between each coat.