tiling a sealed gypsum screed??? Advice needed

[davy_G]

Hi all,
I was looking at a friends not so new, new build this evening.

He wants a decent amount of tiling done. The main job is on a sealed gypsum screed.
The screed was put in and polished about a year ago. It is over a wet UFH system.

They where advised to seal the screed with an water based arcylic sealer, this was done.

It looks very much like a garage floor paint, with not much info on the used tin.

I intended to get the UFH turned down to +/-10C. Prime with SBR (this is the bit i have the problem with!) and tile with flexi addy & grout.

The problem i have is the floor is highly polished and the sealer is quite glossy. and the worrying bit. Another chap, whos work they are not happy with, did the bathroom and the floor tiles have started to debond. The tiler supplied the adhesive and grout so i have no idea as to its suitability.
I hava asked my mate to lift some of the tiles as he is going to attempt a remair job and see where it has debonded, if its clean from the sealer and all the adhesive is on the tile that will worry me, if it pants adhesive then im happy enough to proceed.

I have an option to acid etch the sealer/paint, then prime. Whats your toughts? There is no point me putting down tiles for them to potentially lift, i dont want a call in 6 months time.

 

[Ian]

Was the screed sanded before it was sealed?

 

[jay]

Think you need to grind or sand the sealer off first so your adh can get a key

 

[Gazzer]

Ajax is the man for this . I would think that sanding the floor would be a start. Why not use a Gypsum adhesive ?

 

[davy_G]

Was the screed sanded before it was sealed?

As in polished?
Yes

 

[Ian]

I mean sanded to remove any laitence? Either way I think you need to do it again to get rid of the primer/sealer as Jay has suggested and from experience, use a gypsum based adhesive as Neale has suggested. Ajax has mentioned before that he is yet to see a failure where gypsum based adhesive has been used but, has seen a few where cement based has.

 

[davy_G]

This is my first gypsum screed ive seen, so bear with me.

Ive only used or seen cement adhesive, who manufactures a gypsum one and have you any idea of cost for one suitable for UFH?

 

[Gazzer]

Just used Nicobond Gypfix, good stuff. Price depends on where you buy it from.

 

[hillhead]

Ask your bro Davy if his company does a gypsum adhesive, i personally have never used one myself.
Two weeks ago i was on a sweet marble job and the company had another tiler starting a house close to where i was, the tiler sanded the floors and scratched them for two days. He then primed and left for a week still unsure if he was going to tile it,lol.

 

[Ian]

The one I've used is Creative Impressions with their own primer, a few of the guys on here have used the N&C gear and that goes on with no primer (screed still needs to be sanded and hoovered) from memory the CI is £32 for a 25k bag, don't know about the N&C but i think it's much cheaper.

 

[Gazzer]

No need to prime with Gypfix.

 

[Gazzer]

The one I've used is Creative Impressions with their own primer, a few of the guys on here have used the N&C gear and that goes on with no primer (screed still needs to be sanded and hoovered) from memory the CI is £32 for a 25k bag, don't know about the N&C but i think it's much cheaper.

Around the £25 mark and I was getting 4m2 a bag.

 

[Ian]

Around the £25 mark and I was getting 4m2 a bag.

Probably not a lot in it then, I got about 5m per bag solid bedding and back skimming.

 

[davy_G]

Ask your bro Davy if his company does a gypsum adhesive, i personally have never used one myself.

I have the larsen addy spec guide infront of me. They say their flexible fast set is recommended for gypsum screeds......it is still cement based though C2F S1, they have an S2 but i doubt that would help!

 

[doug boardley]

Davy, was ufh banged up too soon in bathroom?

 

[Gazzer]

Probably not a lot in it then, I got about 5m per bag solid bedding and back skimming.

Only 20kg bags but save on primer. I expect gypsum prices to fall slightly as more manufacturers release their versions.

 

[Ian]

I'd like to think so Neale, still £25 isn't ridiculous when you compare it to BAL SPF, retail at Topps!!!!!!


Sent from iPhone using tapatalk

 

[davy_G]

Davy, was ufh banged up too soon in bathroom?

It could have been, it might not be flexible addy. I just dont know. I want to see the method of debonding when the tiles are lifted.

 

[Ajax123]

Are you absolutely sure this is a gypsum screed. Reason I ask is that they do not generally polish well.

If it is then sand it and use gypsum adhesive would be my advice

 

[davy_G]

Are you absolutely sure this is a gypsum screed. Reason I ask is that they do not generally polish well.

If it is then sand it and use gypsum adhesive would be my advice

It is the CEMEX supaFlo, Screed | CEMEX UK

Spoke to Cemex technichal guy and we are all along the same lines.

Thanks for all the replies folks.

 

[Ajax123]

Ok with it being supaflo and I am assuming it's in Ireland it will be one of our screeds. Not generally suited to polishing but it is what it is. I would sand of the sealer that is on it and then treat it asa new screed I.e check it's dry, make sure the heating has been run up to temp, prime it if required the use a gypsum addy. Not sure who supplies in Ireland but pci and forbo flooring have them as well as reative impressions and nicobond. You are unlikey to find these adhesives in tile outlets and will probably need to contact the manufacturers themselves. If you decide to us ement the priming is critical. Make sure you use a good quality penetrative primer, ideally epoxy.

 

[davy_G]

Ok with it being supaflo and I am assuming it's in Ireland it will be one of our screeds. Not generally suited to polishing but it is what it is. I would sand of the sealer that is on it and then treat it asa new screed I.e check it's dry, make sure the heating has been run up to temp, prime it if required the use a gypsum addy. Not sure who supplies in Ireland but pci and forbo flooring have them as well as reative impressions and nicobond. You are unlikey to find these adhesives in tile outlets and will probably need to contact the manufacturers themselves. If you decide to us ement the priming is critical. Make sure you use a good quality penetrative primer, ideally epoxy.

Yep in N Ireland. We intend to remover the sealer/paint by sanding (well my mate will). Your right about gypsum addy not being available over here, im struggling.
Would you recommed this type of epoxy primer? Not something ive come across before!
PCI Epoxy Primer VG 7
I was going to use a couple of coats of latex based primer, SBR
http://www.**************/acatalog/siliconing_tiles.html

Thanks in advance for the valuable advice...

 

[Rich]

I would spend an hour or so in front of the computer and do a good old search on here about it. I have done a couple now (with the help of the guys on here especially Ajax). I used the Weber gypsum adhesive. The problem I found is that so few people know about it, I phoned my weber supplier and they had never heard of it, phoned weber and they had never heard of it!! I had to get hold of Allen to give me the number of the one guy in the country that knows what I was going on about.


It will be fine as long as you follow the advice given by Mr Ajax.

 

[Ajax123]

Ok. Before I give you the low down on the primers I will make a couple of calls Monday morning to see if I can locate a stockist in your neck of the woods. What sort of tiles are you sticking down? Did I miss that earlier in the thread?

 

[Ajax123]

It will be fine as long as you follow the advice given by Mr Ajax.

No pressure then