Gypsum based adhesives

[Dumbo]

I as yet have not been brave enough to use a gypsum based adhesive on an anhydrate screed just wondering has anybody on here used them and if so how they have found them and most importantly any failures.

 

[hmtiling]

I as yet have not been brave enough to use a gypsum based adhesive on an anhydrate screed just wondering has anybody on here used them and if so how they have found them and most importantly any failures.

I've used Norcross tile to gypsum, Nicobond gypfix, Granfix csa and Tilemaster anhyfix. No failures and there shouldn't be if used correctly and not in wet areas. Also used Kerakoll h40 ideal which isn't a gypsum adhesive as such but is suitable for anhydrite screeds.

 

[Rich Midge]

Used Norcros and TileMaster both without any issues. TM was supplied considerably cheaper but is most likely superior imo (not a big fan of Norcros)

 

[Ajax123]

not used directly but have recommended for at least 8 years now. seen dozens of failures with cement adhesives in that time. on the other hand have only seen 2 failures with gypsum adhesive over the same period. both of those were easily explained. I don't know why you think using gypsum adhesive is a brave thing to do. It seems just common sense to me. cement on cement and gypsum on gypsum...

 

[Dumbo]

not used directly but have recommended for at least 8 years now. seen dozens of failures with cement adhesives in that time. on the other hand have only seen 2 failures with gypsum adhesive over the same period. both of those were easily explained. I don't know why you think using gypsum adhesive is a brave thing to do. It seems just common sense to me. cement on cement and gypsum on gypsum...

I never trust adhesive manufacturers fully as I have seen lots of failures on some of their products like 2 part flexible rubber crumb adhesive. And having been dumped on by bal over grout which dried out grey instead of limestone but they still claimed it was in the expected colour spectrum . So I would prefer to others who have used the product and as you know you learn more when you have problems than when everything goes perfectly

 

[Fix it Jon]

A gypsum based adhesive is fine if it is mixed correctly and the screed has been properly prepared and is dry. However if the gypsum screed has UFH in it as many of them have, then I would recommend decoupling it, so you would have to go down the cement based route.

 

[hmtiling]

A gypsum based adhesive is fine if it is mixed correctly and the screed has been properly prepared and is dry. However if the gypsum screed has UFH in it as many of them have, then I would recommend decoupling it, so you would have to go down the cement based route.

Why would you have to go the cement based route with a decoupler Jon?
If stone, i would decouple and use gypsum adhesive under and cement based on top but only switching to cement based for cost reasons

 

[Fix it Jon]

With some of the decoupling membranes they don't recommend using a gypsum based adhesive. If you are using Ditra then I believe you can use them but I would still use a cement based adhesive on top, I think the bond strength is better than a gypsum based adhesive.

 

[J Sid]

Ditra is fix with cement based or Ardex AF200 only

 

[Dumbo]

Ditra is fix with cement based or Ardex AF200 only

I've seen fixed on concrete substrate with carpet spray . Although it was curling up before he started fitting tiles

 

[hmtiling]

I can't see why gypsum addy wouldn't work with any fleece backed decoupler. It's only that they haven't tested and think it's way overdue that they do.

 

[J Sid]

agree Harry, probably just not been tested, but until it us the they will not guarantee it

 

[hmtiling]

@Schlüter-Systems Ltd

 

[Rich Midge]

I think I read on a previous thread that TM were onto this.

 

[Qwerty]

@Mark@Tilemaster

 

[goz]

Used Tilemaster Anhyfix plenty of times on anhydrite and alpha hemihydrite screeds, touch wood never had a failure, Mark Kelly's service is second to none, his confidence in his product and his willingness to improve and speak directly to customers make me confident in taking on these projects.
Anhyfix for me

 

[Dumbo]

Used Tilemaster Anhyfix plenty of times on anhydrite and alpha hemihydrite screeds, touch wood never had a failure, Mark Kelly's service is second to none, his confidence in his product and his willingness to improve and speak directly to customers make me confident in taking on these projects.
Anhyfix for me

Don't here many people talk about alpha hemi hydrate. Tom mayhew easy screed by any chance.

 

[hmtiling]

Don't here many people talk about alpha hemi hydrate. Tom mayhew easy screed by any chance.

Yep, he's the only guy who does them where i am. His screeds are great i.e. flat but his advice is not!

 

[Dumbo]

Yep, he's the only guy who does them where i am. His screeds are great i.e. flat but his advice is not!

Did one of his yesterday .first class also got him to do my house . Unbelievable quality .

 

[hmtiling]

Did one of his yesterday .first class also got him to do my house . Unbelievable quality .

I'm hoping you haven't been following his advice though mate

 

[Dumbo]

Yep, he's the only guy who does them where i am. His screeds are great i.e. flat but his advice is not!

Also very good for laying engineered wood on as well .

 

[Dumbo]

Yep, he's the only guy who does them where i am. His screeds are great i.e. flat but his advice is not!

Also very good for laying engineered wood on as well .

I'm hoping you haven't been following his advice though mate

I always give the floor a quick rub with a stone . Then prime with 2 coats sbr. Not had a failure yet . My floor in my house has been down for several years now with no loose sounding tiles or any cracked grout .

 

[Dumbo]

I'm hoping you haven't been following his advice though mate

What's your prep .

 

[hmtiling]

What's your prep .

Light sand as not much laitence but still a little, commission heating if any, test with hygrometer and tile with gypsum adhesive. I'll suggest decoupling on every one as these screeds do crack but will still tile them without if not stone.

 

[Dumbo]

I'm hoping you haven't been following his advice though mate

What's your prep .

Light sand as not much laitence but still a little, commission heating if any, test with hygrometer and tile with gypsum adhesive. I'll suggest decoupling on every one as these screeds do crack but will still tile them without if not stone.

To be honest always commission heating and yes test for moisture and yes also recommend decoupling but few like the extra expense.

 

[Dumbo]

Light sand as not much laitence but still a little, commission heating if any, test with hygrometer and tile with gypsum adhesive. I'll suggest decoupling on every one as these screeds do crack but will still tile them without if not stone.

Had a few customers that didn't like Tom's price . Had floor done by builder after his assurance it would be good then wish they paid the extra.

 

[Ajax123]

not much alphahemi hydrate used in the UK anymore. I suspect it will die a death eventually due to the coal fired power stations being phased out.

 

[Dumbo]

not much alphahemi hydrate used in the UK anymore. I suspect it will die a death eventually due to the coal fired power stations being phased out.

This is a knauff product which I believe he imports from Belgium. What is relevance of coal powered fire station is their a by production it

 

[hmtiling]

Had a few customers that didn't like Tom's price . Had floor done by builder after his assurance it would be good then wish they paid the extra.

Can't disagree about how good these are to tile once prepped

 

[Dumbo]

Still better get to work . Early start today .